Chemistry As And Alevel

Front 1

What is organic chemsitry?

Back 1

It is the chemistry of compounds derived from living systems

Front 2

Give examples of organic compounds in everyday liffe?

Back 2

1. Pharmaceuticals

2. Detergents

3. Dyes and pigments

4. Cosmetics

5. Plastics

6. Agricultural chemicals

Front 3

What is a hydrocarbon?

Back 3

It is a compound containing carbon and hydrogen

Front 4

What are the two subdivisions of hydrocarbons?

Back 4

Saturated and unsaturated

Front 5

Describe saturated hydrocarbons?

Back 5

They are hydrocarbons that has single bonds only

Front 6

Describe unsaturated hydrocarbons?

Back 6

They are hydrocarbons that caontai carbon-to-carbon multiple (double) bonds

Front 7

Define a homologous series?

Back 7

It is a series of organic compounds with the same functional group but with each successive member differing by a CH2

Front 8

What is the simplest homologous series?

Back 8

The alkanes

Front 9

Describe alkanes?

Back 9

They contain only single carbon-to-carbon double bonds

Front 10

Give the first four members of the alkanes?

Back 10

Methane, Ethane, Propane, Butane

Front 11

What is the bond angle around a carbon in an alkane?

Back 11

109.5 as it is a tetrahedral structure

Front 12

Define a functional group?

Back 12

It is the par of the organic molecule responsible for its chemical reactions

Front 13

Why can hydrocarbons form molecules containing different functional groups?

Back 13

Because carbon can bond to other elements than just hydrogen, including oxygen, nitrogen and halogens

Front 14

What are the three things that hydrocarbons can be classified as?

Back 14

1. Aliphatic

2. Alicyclic

3. Aromatic

Front 15

What is an aliphatic hydrocarbon?

Back 15

It is a hydrocarbon where the carbon atoms are joined to each other in unbranched (straight) or branched chains

Front 16

What is an alicyclic hydrocarbon?

Back 16

It is a hydrocarbon in which the carbon atoms are joined to each other in ring (cyclic) structures that is not aromatic

Front 17

What is an aromatic hydrocarbon?

Back 17

It is a hydrocarbon in which some or all of the carbon atoms are found in a benzene ring

Front 18

What are the three homologous series of aliphatic hydrocarbons?

Back 18

1. Alkanes

2. Alkenes

3. Alkynes

Front 19

Define alkanes?

Back 19

The hydrocarbon homologous series with single carbon-to-carbon bonds and the general formula CnH2n+2

Front 20

Define alkenes?

Back 20

The hydrocarbon homologous series with at least one double carbon-to-carbon bond and the general formula CnH2n

Front 21

Define alkynes?

What is the general fomula?

Back 21

The hydrocarbon homologous series with at least one triple carbon-to carbon bond and the general formula CnH2n-2

Front 22

What does the stem of the name of a hydrocarbon indicate?

Back 22

The number of carbon atoms in the longest continous chain in the molecule

Front 23

What does the prefix in the name of a hydrocarbon indicate, and where is it placed in relation to the stem?

Back 23

A prefix can be added before the stem, often to indicate the presence of side chains of a functional group

Front 24

What is the suffix in the name of a hydrocarbon used to indicate and where is this placed?

Back 24

It is added after the stem and indicates the functuional groups

Front 25

What suffix do all alkenes have?

Back 25

-ene

Front 26

How do you name aliphatic alkanes?

Back 26

1. They all have the suffix -ane

2. Identify the longest carbon chain and name it

3. Identify any side chains - known as alkyl groups and add it as a prefix

4. Add numbers before any alkyl groups to show the position of the them on the carbon chains

Front 27

Define an alkyl group?

Back 27

It is a side chain formed by removing a hydrogen atom from an alkane parent chain

Front 28

What is any alkyl group displayed as?

Back 28

R

Front 29

What is the aklane with 1 carbon atom?

Back 29

Methane

Front 30

What is the aklane with 2 carbon atoms?

Back 30

Ethane

Front 31

What is the alkane with 3 carbon atoms?

Back 31

Propane

Front 32

What is the alkane with 4 carbon atoms?

Back 32

Butane

Front 33

What is the alkane with 5 carbon atoms?

Back 33

Pentane

Front 34

What is the alkane with 6 carbon atoms?

Back 34

Hexane

Front 35

What is the alkane with 7 carbon atoms?

Back 35

Heptane

Front 36

What is the alkane with 8 carbon atoms?

Back 36

Octane

Front 37

What is the alkane with 9 carbon atoms?

Back 37

Nonane

Front 38

What is the alkane with 10 carbon atoms?

Back 38

Decane

Front 39

How many carbon atoms does methane have?

Back 39

1

Front 40

How many carbon atoms does ethane have?

Back 40

2

Front 41

How many carbon atoms does propane have?

Back 41

3

Front 42

How many carbon atoms does butane have?

Back 42

4

Front 43

How many carbon atoms does pentane have?

Back 43

5

Front 44

How many carbon atoms does hexane have?

Back 44

6

Front 45

How many carbon atoms does heptane have?

Back 45

7

Front 46

How many carbon atoms does octane have?

Back 46

8

Front 47

How many carbon atoms does nonane have?

Back 47

9

Front 48

How many carbon atoms does decane have?

Back 48

10

Front 49

What is the formula of methane?

Back 49

CH4

Front 50

What is the formula of ethane?

Back 50

C2H6

Front 51

What is the formula of propane?

Back 51

C3H8

Front 52

What is the formula of butane?

Back 52

C4H10

Front 53

What is the formula of pentane?

Back 53

C5H12

Front 54

What is the formula of hexane?

Back 54

C6H14

Front 55

What is the formula of heptane?

Back 55

C7H16

Front 56

What is the formula of octane?

Back 56

C8H18

Front 57

What is the formula of nonane?

Back 57

C9H20

Front 58

What is the formula of decane?

Back 58

C10H22

Front 59

What is the alkyl group of the parent alkane methane?

What is its formula?

Back 59

Methyl

CH3

Front 60

What is the alkyl group of the parent alkane ethane?

What is its formula?

Back 60

Ethyl

C2H5

Front 61

What is the alkyl group of the parent alkane propane?

What is its formula?

Back 61

Propyl

C3H7

Front 62

What is the alkyl group of the parent alkane butane?

What is its formula?

Back 62

Butyl

C4H9

Front 63

What is the alkyl group of the parent alkane pentane?

What is its formula?

Back 63

Pentyl

C5H11

Front 64

What is the alkyl group of the parent alkane hexane?

What is its formula?

Back 64

Hexyl

C6H13

Front 65

What is the alkyl group of the parent alkane heptane?

What is its formula?

Back 65

Heptyl

C7H15

Front 66

What is the alkyl group of the parent alkane octane?

What is its formula?

Back 66

Octyl

C8H17

Front 67

What is the alkyl group of the parent alkane nonane?

What is its formula?

Back 67

Nonyl

C9H19

Front 68

What is the alkyl group of the parent alkane decane?

What is its formula?

Back 68

Decyl

C10H21

Front 69

What classifcation of hydrocarbons is this?

Back 69

Alicyclic

Front 70

What classifcation of hydrocarbons is this?

Back 70

Aliphatic

Front 71

What classifcation of hydrocarbons is this?

Back 71

Aromatic

Front 72

Draw a alicylic hydrocarbon?

Back 72

Front 73

Draw an aliphatic hydrocarbon?

Back 73

Front 74

Draw an aromatic hydrocarbon?

Back 74

Front 75

When there are two or more possible chains of the same length in a molcule, which is considered the longest cahin?

Back 75

The chain with the most branches

Front 76

What must be stated for alkenes that have four or more carbon atoms in their longest chain?

Back 76

The position of the C=C bond

Front 77

What number is used to indicate the position of the C=C bond in an alkene?

Back 77

The smallest number, so if it is between carbon 2 and 3, only the number two is used to represent its position

Front 78

What is the functional group of an alkene, drawing?

What is the suffix?

Back 78

-ene

Front 79

What is the functional group of an alcohol, drawing?

What is the suffix?

What is the prefix?

Back 79

-ol

hydroxy-

Front 80

What is the functional group of a haloalkane, drawing?

What is the preffix?

Back 80

chloro- bromo- iodo-

Front 81

What is the functional group of an aldehyde, drawing?

What is the suffix?

Back 81

-al

Front 82

What is the functional group of an ketone, drawing?

What is the suffix?

Back 82

-one

Front 83

What is the functional group of an carboxylic acid, drawing?

What is the suffix?

Back 83

-oic acid

Front 84

What is the functional group of an ester, drawing?

What is the suffix?

Back 84

-oate

Front 85

What is the functional group of an acyl chloride, drawing?

What is the suffix?

Back 85

-oyl chloride

Front 86

What is the functional group of an amine, drawing?

What is the suffix?

What is the prefix?

Back 86

-amine

amino-

Front 87

What is the functional group of a nitrile, drawing?

What is the suffix?

Back 87

-nitrile

Front 88

What is the letter functional group of an alkene?

Back 88

C=C

Front 89

What is the letter functional group of an alcohol?

Back 89

-OH

Front 90

What is the letter functional group of an haloalkane?

Back 90

-Cl -Br -I

Front 91

What is the letter functional group of an aldehyde?

Back 91

-CHO

Front 92

What is the letter functional group of an ketone?

Back 92

-C(CO)C-

Front 93

What is the letter functional group of an carboxylic acid?

Back 93

-COOH

Front 94

What is the letter functional group of an ester?

Back 94

-COOC-

Front 95

What is the letter functional group of an acyl chloride?

Back 95

-COCl

Front 96

What is the letter functional group of an amine?

Back 96

-NH2

Front 97

What is the letter functional group of an nitrile?

Back 97

-CN

Front 98

What is the general formula for alcohols?

Back 98

CnH2n+1OH

Front 99

What is the general formula for carboxylic acids?

Back 99

CnH2nO2

Front 100

What is the general formula for ketones?

Back 100

CnH2nO

Front 101

What is the molecular formula?

Back 101

A formula that shows the number and type of atoms of each element present in a molecule

Front 102

What is the empricial formula?

Back 102

The formula that shows the simplest whole-number ratio of atoms of each element present in a compound

Front 103

What is the general formula?

Back 103

The simplest algebraic formula of a member of a homologous series. For example, the general formula of the alkanes is CnH2n+2

Front 104

What is the displayed formula?

Back 104

It is a forumla showing the relative positioning of all the atoms in a molecule and the bonds between them

Front 105

What is the skeletal formula?

Back 105

A simplified organic formula with hydrocarbon atoms removed from alkyl chains leaving just a carbon skeleton and associated functional groups

Front 106

What is the structual formula?

Back 106

A formula showing the minimal detail for the arrangement of atoms in a molecule

Front 107

What are structural isomers?

Back 107

Molecules with the same molecular formula but with different structural formulae

Front 108

Give the empririal formula of glucose?

C6H12O6

Back 108

CH2O

Front 109

What type of formulae does this show?

Back 109

Displayed Formula

Front 110

What type of formulae does this show?

Back 110

Displayed Formula

Front 111

What type of formulae does this show?

Back 111

Structural formula

Front 112

What type of formulae does this show?

Back 112

Structural formula

Front 113

What type of formulae does this show?

Back 113

Skeletal formula

Front 114

What type of formulae does this show?

Back 114

Skeletal formula

Front 115

Give the structural formula of butane?

Back 115

CH3CH2CH2CH3

or

CH3(CH2)2CH3

Front 116

Give the structural formula of pentane?

Back 116

CH3CH2CH2CH2CH3

or

(CH3)2CHCH2CH3

or

C(CH3)4

Front 117

If an alkane has 1 carbon, how many structural isomers does it have?

Back 117

1

Front 118

If an alkane has 2 carbons, how many structural isomers does it have?

Back 118

1

Front 119

If an alkane has 3 carbons, how many structural isomers does it have?

Back 119

1

Front 120

If an alkane has 4 carbons, how many structural isomers does it have?

Back 120

2

Front 121

If an alkane has 5 carbons, how many structural isomers does it have?

Back 121

3

Front 122

If an alkane has 6 carbons, how many structural isomers does it have?

Back 122

5

Front 123

If an alkane has 7 carbons, how many structural isomers does it have?

Back 123

9

Front 124

If an alkane has 8 carbons, how many structural isomers does it have?

Back 124

18

Front 125

If an alkane has 9 carbons, how many structural isomers does it have?

Back 125

35

Front 126

If an alkane has 10 carbons, how many structural isomers does it have?

Back 126

75

Front 127

What is the skeleteal formula a simplified version of?

Back 127

The organic formula

Front 128

What do you remove when doing the skeletal formula?

Back 128

1. All of the carbon and hydrogen labels from carbon chains

2. Any bonds to hydrogen atoms

Front 129

In skeletal formulae, what does a line represent?

What does an intersection of two lines represent?

What does the end of a line represent?

Back 129

A single bond

A carbon atoms

A -CH3 group

Front 130

What is one of the most common uses of skeletal formula?

Back 130

In representing alicyclic and aromatic compounds

Front 131

What hydrocarbon does this show?

Draw it out - displayed formula

Back 131

Cyclohexene

Front 132

What does this show?

Draw it out - skeletal formula

Back 132

Cyclohexene

Front 133

Draw cyclohexene?

Back 133

Front 134

Draw the skeletal formula of cyclohexene?

Back 134

Front 135

What skeletal formula does this show?

Back 135

Benzene

Front 136

What skeletal formula does this show?

Back 136

Benzene

Front 137

What display formula does this show?

Back 137

Benzene

Front 138

Draw the display formula of benzene?

Back 138

Front 139

Draw the skeletal formula (1) of benzene?

Back 139

Front 140

Draw the skeletal formula (2) of benzene?

Back 140

Front 141

What happens when drawing skeletal formula if there is a functional group present in the molecule?

Back 141

They must also be included in the skeletal formula

Front 142

Define isomers

Back 142

Different compounds with the same molecular formula

Front 143

Define structural iosmers?

Back 143

They are compounds with the same molecular formula but different structural formulae

Front 144

Describe two isomers with different functional group and molecular formula?

Back 144

They can have different functional groups but the same molecular formula, for example Aldehydes and ketones with the same number of carbon atoms

Front 145

What are the two processes by which covalent bonds can be broken?

Back 145

1. Homolytic fission

2. Heterolytic fission

Front 146

Describe what happens in homolytic fission?

Back 146

1. When a covalent bond breaks, each of the bonded atoms takes one of the shared pair of electrons

2. Each atom now has a single unpaired electron

3. Atoms or groups of atoms with an unpaired electron is called a radical

Front 147

Draw the products of the homolytic fission of ethane?

H3C-CH3 --> ?

Back 147

H3C O + O CH3

Where O is a radical

Front 148

What happens in heterolytic fission?

Back 148

1. When a covalent bond breaks by heterolytic fission, one of the bonded atoms takes both of the eletrons from the bond

2. The atom that takes both electrons becomes a negative ion

3. The atom that does not take electrons becomes a positive ion

Front 149

Describe the products of this heterolytic fission of chloromethane?

H3C-Cl --> ?

Back 149

H3C^+ + Cl^-

Front 150

What does an equation tell you?

What doesn't an equation tell you?

Back 150

About the reactants, the products and stioichiometry of the reaction

Information about how the reaction takes place

Front 151

Define the reaction mechanism?

Back 151

The sequence of bond breaking and bond forming steps that shows the path taken by electrons during a reaction

Front 152

Define a radical?

Back 152

A species with an unpaired electron

Front 153

In a reaction mechanism what are curly arrows used to show?

Back 153

The movement of electron pairs when bonds are being broken or made

Front 154

Define an addition reaction?

Back 154

When two reactants join together to form one product

Front 155

Define a substitution reaction?

Back 155

When an atom or group of atoms is replaced by a different atom or group of atoms

Front 156

Define an elimination reaction?

Back 156

A reaction that involves the removal of a small molecule from a larger one. One reaction molecule forms two products

Front 157

Give an example of an addition reaction?

Back 157

The addition of water to an unsaturated alkene (in which the double bond is broken)

Front 158

Where do substitution reactions occur? Specifically

Back 158

In the chemistry of the haloalkane functional group

Front 159

Give an example of an eleimination reaction?

Back 159

The elimination of a water molecule from an alcohol

Front 160

What are alkanes the main components of?

Describe their stability?

What has this allowed?

Back 160

Natural gas and crude oil

They are amongst the most stable - unreactive organic compounds

Crude oil deposits to remain in the Earth for millions of years

Front 161

What are alkanes mainly used as?

What are they reacted with to give what?

Back 161

As fuels

With oxygen to generate heat

Front 162

What is the general formula of alkanes?

Back 162

CnH2n+2

Front 163

What form or hydrocarbons are alkanes?

Back 163

They are saturated, containing only carbon and hydrogen atoms joined together by single covalent bonds

Front 164

Describe the bonding of a carbon atom in an alkane?

What are these called?

Back 164

They are bonded for four other atoms by single covalent bonds

Sigma bonds

Front 165

What is a sigma bond?

Back 165

The result of the overlap of two oribtals in a covalent bond, one from each bonding atom. Each overlapping oribtal contains one electron, so the sigma bond has two electrons that are shared between the bonding atoms

Front 166

Describe the positioning of a sigma bond?

Back 166

It is positioned on a line direclty between the bonding atoms

Front 167

Draw the stages of formation of a sigma bond?

Back 167

Front 168

What is the symbol for a sigma bond?

Back 168

Front 169

What does this symbol mean?

Back 169

It represents a sigma bond

Front 170

Describe the solubility of hydrocarbons?

Back 170

Hydrocarbons are insoluble in polar solvent like water because they are predominantly non-polar in nature. However, they are soluble in nonpolar solvents

Front 171

What is the shape arrangement around each carbon atom in an alkane? Why?

Back 171

Each crabon atom is surronded by four electron pairs in four sigma bonds. Repulsion between these electron pairs results in a 3D tetrahedral arrangement with each bond angle bieng 109.5 degrees

Front 172

Describe why butane can form different shapes? Not in terms of structural isomers

Back 172

Because the sigma bonds acts as axes around which the atoms can rotate freely, so these shapes are not rigid

Front 173

How are crude oil fractions (alkanes) seperated?

Back 173

By fractional distillation in a distillation tower

Front 174

Why is seperation possible in a distillation tower of alkanes?

Back 174

Because the boiling points of the alkanes are different, increasing as their chain length increases

Front 175

Describe the trend in boiling point of the alkanes?

Back 175

As the number of carbon atoms increases, i.e. their chain increases the boiling points increases

Front 176

Explain the increase in the boiling points of the alkanes as the chain length increases?

Back 176

Because there are weak London forces between the chains. As the chain length increases, the molecules have a larger surface area, so more contact is possible between the molecules. The london forces between the molecules with be greater and so more energy is required to overcome the forces

Front 177

Describe what happens when you compare the boiling point of branched isomers with striahgt chain isomers of the same molecular mass?

Back 177

The branched isomers have a lower boiling point

Front 178

Describe the difference in melting and boiling point between pentane (top) and 2-methylbutane (bottom)?

Back 178

They have the same molecular mass, but pentane has a high melting and boiling point than 2-methylbutane.

This is because there are fewer surface points of contact between molecules of the branched alkanes, giving fewer london forces.

The branches get in the way and prevent the branched molecules getting as close as straight chain molecules, decreasing the intermolecular forces further

Front 179

Why are the two reasons that branching of isomers of the same molecular mass decreases their boiling point?

Back 179

1. There are fewer surface points of contact between molecules of the branched alkanes, giving fewer london forces.

2. The branches get in the way and prevent the branched molecules getting as close as straight chain molecules, decreasing the intermolecular forces further

Front 180

Describe the strenght of the bonds in an alkane?

Back 180

The C-C and C-H bonds are strong

Front 181

Describe the polarity of the bonds in an alkane?

Back 181

The C-C bonds are non-polar

The C-H bonds are considered non polar because the electronegativities of the two elements are similar

Front 182

What do alkanes produce when they react with oxygen?

What is this reaction called?

What else do they give out?

Back 182

Carbon dioxide and water

Combustion

Heat

Front 183

Why are alkanes good fuels?

Back 183

1. They give out heat

2. They are readily available

3. They burn in a plentiful supply of oxygen

4. They do not release toxic products during combustion

Front 184

Describe the conditions required for incomplete combustion?

Back 184

A limited supply of oxygen - not enough for complete combustion

Front 185

Describe what happens to alkanes when they burn in a limited supply of oxygen?

Back 185

The hydrogen atoms are always oxidised to water but the combustion of the carbon may be incomplete forming carbon monoxide or even carbon as soot

Front 186

Describe carbon monoxide?

Back 186

It is a colourless, odourless and highly toxic gas. It combones with haemoglobin in red blood cells which prevents haemoglobin from transporting oxygen around the body

Front 187

What condition is needed for the reaction of alkanes with halogens?

Back 187

The presence of sunlight, as this provides the high-energy ultraviolet radiation which constitutes the initial energy for the reaction to take place

Front 188

CH4 + Br2 ---> ?

Back 188

CH3Br + HBr

Front 189

What type of reeaction is the reaction between methane and bromine?

Back 189

It is a subsititution reaction as a hydrogen atom in the alkane had been subsitutied by a halogen atom

Front 190

What is the reaction mechanism?

Back 190

The series of steps of a chemical reaction showing how electrons are thought to move during the reaction

Front 191

What mechanism in the bromination of methane?

Back 191

It is an example is radical substitution

Front 192

What three stages does radical substitution take place in?

Back 192

1. Initiation

2. Propagation

3. Termination

Front 193

Describe the inititation stage of radical substitution?

(Bromine as example)

Back 193

1. The reaction is started when the covalent bond in a bromine molecule is broken by homolytic fission, forming two highly reactive bromine radicals

2. This energy for this fission is provided by UV radiation

Front 194

Describe the propagation step of radical substitution?

(Bromine as an example)

Back 194

1. First step: the bromine radical reacts with the C-H bond in the methane, forming a methyl radical and a molecule of hydrogen bromide

2. Second step: each methyl radical reacts with another bromine molecule, forming the organic product bromomethane together with a new bromine radical.

3. The new bromine radical then reacts with another CH4 molecule as in the first step and the two steps continue to cycle as a chain reaction

Front 195

How long should the propagation steps continue?

Back 195

Untill the reactants have been used up, when radicals collide. It has been estimated that up to a million propagation cycles take place before a termination step stops the reaction

Front 196

Describe the termination step of free radical substitution?

Describe the combinations of products?

Back 196

Two radicals collide, forming a molecule with all electrons paired. When they collide and react, both radicals are removed from the reaction mixture, stopping the reaction

There are a number of possible termination steps with different radicals in the reaction mixture.

Front 197

What stage of a free radical substitution is this?

Back 197

Initiation

Front 198

What stage of a free radical substitution is this?

Back 198

Propagation

Front 199

What stage of a free radical substitution is this?

Back 199

Termination

Front 200

Draw the equation for initiation in free radical substituion of chlorine?

Back 200

Front 201

Draw the two equations for propagation in free radical substituion of chlorine and methane?

Back 201

Front 202

Draw the two possible equations for termination in free radical substituion of chlorine and methane?

Back 202

Front 203

Give the limitations of radical substitution in organic synthesis of one organic compound?

Back 203

1. Further substitution

2. Substitution at different positions in a carbon chain

Front 204

Describe why further substitution is a limitation of radical substitution in organic synthesis?

(use CH3Br as the example)

Back 204

If CH3BR was formed in the second propagation step, another bromine radical can collide with it, subsituting a further hydrogen atom to form CH2Br2. This can continue untill all the hydrogen atoms have been substituted. The result is a mixture of CH3Br, CH2BR, CHBr3 and CBr4

Front 205

Describe why substitution is a limitation of radical substitution in organic synthesis?

(use CH3Br as the example)

Back 205

For methane, all four hydrogen atoms are bonded to the same carbon atom, so only one monobromo compound is possible.

If the carbon chain is longer, you can get a mixture of monosubstituted isomers, by substitution at different positions in the carbon chain.

Front 206

What is the general formula of alkenes?

Back 206

CnH2n

Front 207

Give the first members of the alkene homologous series?

Back 207

1. Ethene

2. Propene

3. But-2-ene

Front 208

Describe the different structures that alkenes can be and the effect on the general formula?

Back 208

Alkenes can be branched, contain more that one double bond or be cyclic. Branched alkenes obey the general formula CnH2n, cyclic alkenes and alkenes with more than one double bond do not

Front 209

Describe the bonding in alkenes?

Back 209

1. Three of the four electrons in its outer shell are used in sigma bonds. One to the other carbon of the double bond, and the other two to other atoms

2. This leaves one electron on each carbon atom of the double bond which is in a p-orbital

3. A π-bond is formed

Front 210

Describe π-bonds?

Where is the electron density concentrated?

Back 210

1. Formed by the sideways overlap of two p-orbitals, one from each carbon atom of the double bond

2. Above and below the line joining the nuclei of the bonding atoms

Front 211

Describe how π-bonds effect the geometry of alkenes?

Back 211

It locks the two carbon atoms in position and prevents them from rotating around the double bond. Therefore, unlike in alkanes, rotation is not possible around every atom

Front 212

Describe how this ethene molecule forms a pi-bond. Label any other bonds present.

Back 212

The line inbetween the two carbons represents a sigma bond

Front 213

Define stereoisomers?

Back 213

Compounds with the same structural formula but with a different arrangement of the atoms in space

Front 214

Name two types of stereoisomerism?

Back 214

1. E/Z isomerism

2. Optical Isomerism

Front 215

What compounds does E/Z isomerism occur in?

Back 215

Those with a C=C double bond

Front 216

What types of compounds does optical isomerism occur in?

Back 216

Coumpounds including alkanes with no functional groups

Front 217

Why does sterioisomerism arise around double bonds?

Back 217

Because the roration about the double bond is resitricted and the groups attached to each carbon atom are therefore fixed relative to each other. The reasons for the rigidity is the position of the π-bonds electron density above and below the plae of the sigma bond

Front 218

What two conditions must a molecule satisfy to have E/Z iosmerism?

Back 218

1. A C=C double bond

2. Different groups attached to each carbon atom of the double bond

Front 219

Describe the E/Z isomers of But-2-ene?

Back 219

The image shows the E isomer, but if both methyl groups are on the same side of the molecule, it is a Z isomer

Front 220

Describe why but-1-ene cannot form E/Z isomers?

Back 220

1. The carbon on the left hand side is attached to two hydrogen atoms

2. This means the structure does not satisfy the condition to have different groups attached to each carbon atom of the double bond

Front 221

What is the name commonly used to describe a special case of E/Z isomerism?

Back 221

Cis-trans isomerism

Front 222

Describe the conditions for cis-trans isomerism?

Back 222

1. Moleculesmust have a C=C double bond

2. Each carbon must be attached to two different groups

3. One of the attached groups must be hydrogen

Front 223

Define nomenclature?

Back 223

A system of naming compounds

Front 224

Draw the trans isomer of but-2-ene?

C4H8

Back 224

Front 225

Draw the cis isomer of but-2-ene?

C4H8

Back 225

Front 226

In cis-trans isomerism: (Z/E)

The cis isomer is the....

The trans isomer is the...

Back 226

.... Z isomer

.... E isomer

Front 227

Some C=C molecules do not have hydrogen attached to both carbons, but what must still be done? (Naming)

Therefore what is used?

Back 227

It must still be named

The E/Z system of naming

Front 228

Who sorted out the naming of molecules with double bonds that do not have hydrogen atoms attached to the carbon atoms of the double bond?

Therefore what was this system of naming called?

Back 228

Cahn and Ingold and Prelog

The Cahn-Ingold-Prelog nomenclature

Front 229

What are the rules of the Cahn-Ingold-Prelog nomenclature?

Back 229

The atoms attached to each carbon atom in a double bond are given priority based upon their atomic number:

1. If the groups of higher priority are on the same side of the double bond, the compound it the Z isomer

2. If the groups of higher priority are diagonally placed across the double bond, the compound is the E isomer

Front 230

What is used to assign priority in the Cahn-Ingold-Prelog rules?

The higher the priority....

Back 230

Atomic number

The higher the atomic number

Front 231

Draw the diagram of the (Z)-isomer using the Chan-Ingold-Prelog rules?

Back 231

Front 232

Draw the diagram of the (E)-isomer using the Chan-Ingold-Prelog rules?

Back 232

Front 233

What happens, when using the Chan-Ingold-Prelog rules if two atoms assigned to the carbon atom have the same priority?

Back 233

You need to find the first point of difference . The group which has the higher atomic number at the first point of difference is given the highest priority.

Front 234

Work out whether this molecule is an E or Z isomer?

Back 234

1. On the left the carbon has priority over the hydrogen

2. On the right the atoms immediately attached are carbon atoms

3. Continue down the chain to the first point of difference, this is at the Cl and O atoms

4. Cl has a higher atomic number so the chain containing Cl is the higher priority

5. The molecule is the Z isomer

Front 235

Are alkenes more or less reactive than alkanes?

Why?

Back 235

They are much more reactive

Because of the presence of the Pi bond, which readily breaks and alkenes undergo addition reactions relativally easily.

Front 236

Give reasons why, due to the presence of the pi-bond alkenes are more reactive than alkanes?

Back 236

1. The exposed nature of the pi-electrons

2. The pi bond has a lower enthalpy than the sigma bond and is therefore broken more readily

Front 237

Give examples of four things that alkenes undergo addition reactions with (also describing nessacary conditions)?

Back 237

1. Hydrogen in the presense of a nickel catalyst

2. Halogens

3. Hydrogen halides

4. Steam in the presence of an acid catalyst

Front 238

What are the conditions for the hydrogenation of alkenes?

Back 238

1. Mixed with hydrogen

2. Passed over a nickel catalyst

3. At 423 K

Front 239

What is formed from the hydrogenation of alkenes?

Back 239

An alkane as hydrogen is added across the double bond

Front 240

What is an addition reaction?

What is the product like?

Back 240

One in which two molecules react together to make one product

The product is saturated

Front 241

If there are two double bonds in an alkene, how many moles of hydrogen are needed to hydrogenate it?

Back 241

Two moles, one per each double bond

Front 242

Draw the product of this reaction?

Name the reaction?

Back 242

It is a hydrogenation reaction

Front 243

What are the conditions for the halogenation of alkenes?

What is halogenation?

Back 243

Room temperature

It is the reaction of an alkene with the halogens chlorine and bromine

Front 244

Draw the product of this reaction?

Name this reaction?

Back 244

It is a halogenation reaction

Front 245

What can bromine water be used to identify?

Back 245

If there is a C=C bond present and the organic compound is unsaturated

Front 246

Describe how bromine tests for double bonds?

Back 246

Bromine adds across the double bond, the organe colour disappears

Front 247

What happens when you add bromine water to an alkane or saturated compound?

Back 247

There is no addition reaction and therefore no colour change

Front 248

What happens when an alkene reacts with a hydrogen halide?

Back 248

It forms a haloalkanes

Front 249

What are the conditions requried for the addition reactions of alkenes with hydrogen halides?

Back 249

1. Gasesous hydorgen halides at room temperature

Front 250

What happens when alkene is a gas during the addition reactions of it with hydrogen halides?

Back 250

The reaction takes place when the two gases are mixed

Front 251

What happens when alkene is a liquid during the addition reactions of it with hydrogen halides?

Back 251

The hydrogen halide is bubbled through it

Front 252

Along the same lines of addition reactions of alkenes with hydrogen halides, what do they also react with?

Back 252

Concentrated hydrochloric or hydrobromic acid, which are solutions of the hydrogen halides in water

Front 253

What happens when an unsymmetrical alkene reacts with an unsymmetrical compound?

Back 253

Two products are possible

Front 254

What is the product of this rection?

Hint: They are both unsymmetrical molecules

Back 254

Front 255

What happens alkenes react with steam?

What type of reaction is this?

Back 255

Alcohols

Hydration

Front 256

What are the conditions needed for hydration reactions of alkenes?

Back 256

The presence of a phosphoric acid catalyst

Front 257

What are hydration reactions used widely for in industry?

Back 257

To produce ethanol from ethane

Front 258

What is the product of this reaction, what is it called?

Back 258

It is a hydration reaction

Front 259

What is the name of the mechanism in which alkenes take part in addition reactions to form satuated compounds?

Back 259

Electophillic addition

Front 260

Define an electrophile?

Back 260

An atom (or group of atoms) which is attracted to an electron rich center or atom where is accepts a pair of electrons to form a new covalent bond. It is an electron pair acceptor

Front 261

Define electrophilic addition?

Back 261

It is an addition reaction in which the first step is attack by an electrophile on a region of high electron density

Front 262

What does the pi bond attract and why?

Back 262

It attracts electrophiles bevause the bond represents a region of high electron desnity because of the presence of the pi-electrons

Front 263

Draw the mechanism for the electrophill addition of hydrogen bromide to ethene?

Back 263

Front 264

Describe the electrophillic addition of hydrogen bromide to but-2-ene?

Back 264

1. Bromine is more electronegative than the hydrogen, so the hydrogen bromide is polar and has an overall dipole

2. The electron pair in the pi-bond is attracted to the partially positive hydrogen atom, causing the double bond to break

3. A bond forms between the hydrogen atom o the H-Br molecule and a carbon atom that was part of the double bond

4. The H-Br bond breaks by heterolytic fission, with the electron pair going to the bromine

5. A bromine ion and a carbocation is formed

6. The Br ion reacts with the carbocation to form the addition product

Front 265

Define a carbocation?

Back 265

An ion that conatins a positively charged carbon atom

Front 266

Draw the electrophilic addition reaction for but-2-ene and bromine?

Back 266

Front 267

Describe the mechanism for the reaction of bromine and but-2-ene?

Back 267

1. Bromine is a non-polar molecule. When bromine apporaches the alkene the pi-electrons interact with the electrons in the Br-Br bond

2. This interaction causes polariusation of the Br-Br bond, with one end of the molecule becomming Br^&+ and the other Br^&-. This is an induced dipole

3. The electron pair in the pi-bond is attrached to the Br^&+ end of the molecule, casuing the double bond to break

4. A bond has now been formed between one of the carbon atoms from the double bonds and a bromine atom

5. The Br-Br bond breaks by heterolytic fission, with the electron pair going to the Br^&- end of the molecule

6. A bromide ion and a carbocation are formed

7. The Br^- ion reacts with the carbocation to form the addition product of the reaction

Front 268

Describe what happens when propene and bromine react in terms of quanities of products formed?

Back 268

1. Electorphillic addition occurs in two steps

2. In the first a carbocation is formed

3. In this reaction two carbocations are possible - a primary and a secondary

4. The positive charge is either on the primary or secondary carbon

Front 269

Describe how carbocations are classified?

Back 269

By the number of alkyl groups attached to the positively charged carbon ion

Front 270

What is a carbocation with three R groups called?

What is a carbocation with one R group called?

Back 270

A tertiary carbocation

A primary carbocation

Front 271

Which carbocations are more stable?

Back 271

Those with more R (alkyl) groups are more stable than those with fewer

Front 272

Describe carbocation stability and what causes it?

Back 272

1. It is linked to the electron-donating ability of alkyl groups.

2. Each alkyl group donates and pushes electrons towards the positive charge of the carbocation

3. The positive charge is spread over the alkyl groups

4. The more alkyl groups attached to the positively charged carbon atom, the more the charge is spread out, making the ion more stable

Front 273

In an addition reaction of a hydrogen halide to an unsymmetical alkene, how can you tell which is the major product?

Back 273

The most stable carbocation is the major product

Front 274

Which of these carbocations are the most stable?

Back 274

The third one is because it is attached to the most methyl groups

Front 275

Draw the first 4 carbocations labelling increasing stability?

Back 275

The third carbocation is the most stable and the first one is the least

Front 276

Define a monomer?

Back 276

A small molecule that combines with many other monomers to form a polymer

Front 277

Define a polymer?

Back 277

A large molecule formed from many thousands of repeat units of smaller molecules known as monomers

Front 278

By which reaction do unsaturated alkene molecules undergo to prodyce long saturated chains containing no double bonds?

Back 278

Addition polymerisation

Front 279

Define addition polymerisation?

Back 279

The formation of a very long molecular chain, by repeated addition reactions of many unsaturated alkene molecules

Front 280

Define an addition reaction?

Back 280

A reaction in which a reactant is added to an unsaturated molecule to make one saturated molecule

Front 281

What determines the properties of a ploymer?

Back 281

The monomer used

Front 282

Describe the conditions used for industrial polymerisation?

Back 282

1. High temperature

2. High pressure

3. Using catalysts

Front 283

Give the general formula for addition polymerisation

Back 283

Front 284

Whatis a repeat unit?

Back 284

A specific arrangement of atoms in the polymer molecule that repeats over and over again

Front 285

Describe how to darw the repeat unit in any addition polymerisation reaction?

Back 285

It is always written in square brackets. After the bracket, you place the letter n to show that there is a large number of repeats

Front 286

How is poly(ethene) made?

Back 286

By heating a large number of ethene monomers at high pressure

Front 287

Describe the uses of poly(ethene)?

Back 287

1. Supermarket bags

2. Shampoo bottles

3. Childrens toys

Front 288

Give the uses of poly(chloroethene)?

What is it also known as?

What can it be used to prepare?

Back 288

Pipes, films and sheeting, bottles, flooring, insualtion and cable sheating

Poly(vinyl chloride) or PVC

Make a polymer that is flexible or rigid

Front 289

Draw Poly(chloroethene)?

Back 289

Front 290

Give the uses poly(propene)?

Back 290

1. Childrens toys

2. Packing crates

3. Guttering

4. Fibre for ropes

Front 291

Draw phenylethene?

What is it also called?

Back 291

Styrene

Front 292

Draw the addition polymerisation reaction of poly(styrene)?

What is it also called?

Back 292

Poly(phenylethene)

Front 293

Give the uses of Poly(phenylethene) or poly(styrene)?

Give the property that makes it suitable for this?

Back 293

1. Packaging material

2. Food trays

3. Cups

Its thermal insulating properties

Front 294

Draw tetraflurorethene?

Back 294

Front 295

Draw the reaction for the formation of poly(tetraflurorethene)?

What else can it be called?

Back 295

Teflon

Front 296

Describe the uses of Teflon/poly(tetrafluroethene)?

Back 296

1. Coating for non-stick pans

2. Permeable membrane for clothing and shoes

3. Cable insulation

Front 297

What is the name of this monomer?

Back 297

Tetrafluroethene

Front 298

What is the name of this monomer?

Back 298

Chloroethene

Front 299

What is the name of this monomer?

Back 299

Phenylethene/styrene

Front 300

Why are polymers good for their uses?

Back 300

1. Readily avaliable

2. Cheap

3. Lack of reactivity - good for storing food

Front 301

Why does polymers being unreactive and therefore good at storing food and chemicals safely also present a problem?

Back 301

It presents a probelm with their disposal. Many alkene-based polymers are non-biodegradable. The gorwing amount of waste has serious effects such as killing marine life

Front 302

How does recycling polymers reduce their envionrmental impact?

Back 302

It conserves fintie dossil fuels as well as decreasing the amount of waste going to landfill

Front 303

Describe the recycling process of polymeres?

Back 303

1. Discarded polymers have to be sorted by type

2. The polymers are chopped into flakes, washed dried and melted

3. The recycled polymer is cut into pellets and used to make new products

Front 304

Why is the disposal of PVC hazardous? 4 things

Back 304

1. High chlorine content

2. Range of additives present in the polymer

3. Dumping in landfill is not sustainable

4. When burnt it releases hydrogen chloride, a corrosive gas and other pollutants

Front 305

How was PVC previously dissposed of?

How is it done now?

Back 305

Grinding it and reusing it to manufacture new products

Using solvents to dissolve it. PVC is then recovered by precipitation

Front 306

Why do alkanes have a high stored energy value?

Back 306

Because they are derived from petroleum of natural gas

Front 307

What makes polymers good as fuels?

Back 307

They have a high stored energy value

Front 308

Describe the use of polymers as fuels?

Back 308

1. Waster polymers can be incinerated to produce heat

2. This generates heat to drive a turbine to produce electricity

Front 309

Define feedstock recycling?

What is the major advantage of it?

Back 309

The chemical and and thermal processes that can reclaim monomers, gases or oil from waste polymers

It is able to handle unsorted and unwashed polymers

Front 310

What do the products generated from feedstock recycling resemble?

What can the products generated from feedstock recycling be used for?

Back 310

Those produced from crude oil in refineries

Raw materials for the production of new polymers

Front 311

What are bioplastcis?

Back 311

They are plastics produced from plant starch, cellulose, plant oils and proteins

Front 312

Why is the use of bioplastics good for the envionrment?

Back 312

1. Sustainable alternative to oil-based products

2. Protects our environment

3. Conserves valuable oil reserves

Front 313

How are biodegradable polymers broken down?

Back 313

By microorganisms into water, carbon dioxide and biological compounds

Front 314

Describe compostable polymers

Back 314

1. They degrade and leave no visible or toxic residues.

2. They are based on poly(lactic acid)

Front 315

Describe the use of supermakets bags made from plant starch?

Back 315

They can be used as bin liners for food waste so that the waste and bag can be composted together

Front 316

What is used when the use of plant-based polymers is not possible?

Describe what they do?

Back 316

Photodegradable oil based polymers

They contain bonds that are weakened by absorbing light to start the degradation. Alternatively light absorbing additives are used.

Front 317

What is the functional group of alchohols?

What is this called?

Back 317

-OH

The hydroxyl group

Front 318

What is the simplest alcohol?

Back 318

Methanol, CH3OH

Front 319

Describe the uses of methanol?

Back 319

1. High preformance fuel because of its eficient combustion

2. Chemical feedstock

3. It can be converted to polymers, paints, solvents, insulation and adhesives

Front 320

Describe the uses of ethanol?

Back 320

1. Alcoholic drinks

2. Fuel

3. Solvent and a feedstock

Front 321

Describe the differemces between alchols and alkanes with the same number of carbons?

Describe the variance with chain length?

Back 321

1. Alcohols are less volatile

2. They have higher melting points

3. They have greater water solubility

The difference becomes much smaller as the length of the carbon chain increases

Front 322

Describe why alkanes are non polar?

Describe the intermolecular forces?

Back 322

Because they have non-polar bonds between the carbon atoms, and the electronegativity of the hydrogen and carbon are very similar, therefore meaning they are non-polar

They are weak London forces

Front 323

Describe why alcohols are polar?

Back 323

Alcohols have a polar O-H bond because of the difference in electronegativity of the oxygen and hydrogen atoms. They have weak Lodon forces and much stronger hydrogen bonds

Front 324

Describe the difference in volatility and boiling points of alkanes and alcohols?

Back 324

1. In liquid state the intermolecular hydrogen bonds hold the alcohol molecules together

2. These bonds must be broken to change the liquid into a gas

3. This requires more energy than the weaker London forces in alkanes

Front 325

Describe the difference in solubility in water between alkanes and alcohols?

Back 325

1. Alkanes are non-polar molecules and cannot form hydrogen bonds with water

2. Alcohols are soluble in water as hydrogen bonds form between the polar -OH group and the water molecules

Front 326

Describe the trend in chain length and solubility of alcohols?

Back 326

As the hydrocarbon chain increases in size, the infleucne of the -OH group becomes relatively smaller and the solubility of the longer-chain alcohols becomes more like that of the hydrocarbons - it decreases

Front 327

What are the three types of alcohols?

Back 327

1. Primary

2. Secondary

3. Tertiary

Front 328

What does the classification of alcohols depend upon>

Back 328

The number of hydrogen atoms and alkyl groups attached to the carbon atom that contains the alcohol functional group

Front 329

What type of alcohol is this?

Back 329

Primary

Front 330

What type of alcohol is this?

Back 330

Secondary

Front 331

What type of alcohol is this?

Back 331

Tertiary

Front 332

Draw a primary alcohol?

Back 332

Front 333

Draw a secondary alcohol?

Back 333

Front 334

Draw a tertiary alcohol?

Back 334

Front 335

Give two primary alcohols?

Back 335

Methanol and ethanol

Front 336

Describe primary alcohols?

Back 336

The -OH group is attached to a carbon atom that is attached to two hydrogen atoms and one alkyl group

Front 337

Give the exception to the primary alcohol rule?

Back 337

Methanol, with three hydrogen atoms and no carbon atoms attached

Front 338

Describe a secondary alcohol?

Back 338

The -OH group is attached to a carbon atom that is attached to one hydrogen atom and two alkyl groups

Front 339

Describe a tertiary alcohol?

Back 339

The -OH group is attached to a carbon atom that is attached to no hydrogen atoms and three alkyl groups

Front 340

What is produced when alcohols burn?

Back 340

When they burn completley in oxygen they produce carbon dioxide and water

Front 341

What type of reaction is the combustion of alcohols?

Back 341

It is exothermic and releases a large quanitity of energy in the form of heat

Front 342

Describe the trend of the number of carbon atoms in the alcohol chain and thr amount of energy produced during combustion?

Back 342

The greater the number of carbon atoms, the greater the quantity of heat released per mole

Front 343

What is the usual oxidising agent for the oxidation of alcohols?

Give the symbol formula

Back 343

A solution of potassium dichromate (VI) and dilute sulfuric acid

K2Cr2O7 and H2SO4

Front 344

Describe the chemistry of the colour change when an lcohol is oxidised?

Back 344

The orange solution containing dichromate (VI ions) is reduced to a green solution containing chromium (III) ions

Front 345

What can primary alchols be oxidised to form?

What does the product depend upon?

Back 345

Either aldehydes or carboxylic acids

The reaction conditions used because aldehydes themselves are also oxidised to carboxylic acids

Front 346

What result does this test for an alcohol show?

Back 346

It is positive - the alcohol has been oxidised

Front 347

What result does this test for an alcohol show?

Back 347

It is negative - the alcohol has not been reduced

Front 348

What is used in oxidation to show the oxidising agent is being used?

Back 348

[O]

Front 349

What are the conditions for the formation of an aldehyde from a primary alcohol?

Back 349

1. Gentle heating

2. Acidified potassium dichromate

3. Under distillation

Front 350

Why is distillation used in the formation of an aldehyde from a primary alcohol?

Back 350

To ensure that the aldehydge is prepared rather than the carboxylic acid. Therefore it is distilled out of the reaction mixture as it forms, preventing any further reactions with the oxidising agent

Front 351

Finish this equation for the oxidation of butan-1-ol?

Back 351

Front 352

Under what conditions must primary alcohols be heated under to form carboxylic acids?

Back 352

1. Heated strongly

2. Under reflux

3. Excess of acidified potassium dichromate

Front 353

Why must an excess of acidified potassium dichromate be used in oxidising a primary alcohol to a carboxylic acid?

Back 353

To ensure that all of the alcohol is oxidised

Front 354

Why must heating under reflux be used in oxidizing a primary alcohol to a carboxylic acid?

Back 354

To ensure that any aldehyde formed initially in the reaction also undergoes oxidation to the carboxylic acid

Front 355

What is the product of this first oxidation?

Back 355

+ H2O

Front 356

What is the product of this second oxidation?

Back 356

+ H2O

Front 357

Draw the stages of this becoming a carboxylic acid?

Back 357

+H2O

Front 358

What are secondary alcohols oxidised to?

What is it not possible to do to these?

Back 358

Ketones

Oxidise them further

Front 359

Describe the conditions needed to produce a ketone from a secondary alcohol?

Back 359

1. Heated

2.under Reflux

3. With oxidizing agent

Front 360

What is the product of the oxidation of propan-2-ol?

Back 360

+H2O

Front 361

Describe the oxidation of tertiary alcohpls?

Back 361

They do not undergo oxidation reactions. Therefore the acidified dichromate remains organe when added to a tertiary alcohol

Front 362

What is a dehydration reaction?

Back 362

Any reaction in which a water molecule is removed from the starting material

Front 363

How do you form an alkene from an alcohol?

Back 363

By heating it inder reflux in the presence of an acid cataluyst such as concentrated sulfuric acid or phosphoric acid

Front 364

Give two acid cataylsts that can be used in dehydrating an alcohol?

Back 364

Concentrated sulfuirc acid

Concentrated phosphoric acid

Front 365

What is formed when you dehydrate an alcohol?

Back 365

An alkene

Front 366

What is the dehydration of an alcohol an example of?

Back 366

An elimination reaction

Front 367

What is the product of this dehydration reaction?

Back 367

Front 368

What is formed when an alcohol reacts with a hydrogen halide?

Back 368

Haloalkanes

Front 369

How can a haloalkane be formed from an alcohol?

Back 369

By reacting it with a hydrogen halide

Front 370

Describe the conditions needed to react a hydrogen halide with an alcohol to form haloalkanes?

Back 370

1. Heat

2. Under reflux

3. With sulfuric acid and a sodium halide so that the hydrogen bromide is formed in the reaction

Front 371

What is the first equation of the reaction for the formation of a haloalkane from a hydrogen halide an alcohol (formation of a hydrogen halide )? Use Br2

Back 371

Front 372

What is the product of this reaction?

Back 372

Front 373

What is the second stage of the reaction of a substitution reaction (formation of a haloalkane from a hydrogen halide an alcohol)?

Back 373

Front 374

What is the product of this reaction

Back 374

Front 375

What is the overall equation for the reaction of propan-2-ol with H2SO4 and NaBr?

Back 375

CH3CHOHCH3 + NaBr + H2SO4 -->

CH3CHBrCH3 + NaHSO4 + H2O

Front 376

What are the basic quickfit apparatus?

Back 376

1. Round bottom or pear-shaped flask

2. Receiver

3. Screw-tap adaptor

4. Condenser

5. Still head

Front 377

Draw a round bottom or pear shaped glass?

Back 377

Front 378

Draw a screw-tap adaptor?

Back 378

Front 379

Draw a condenser?

Back 379

Front 380

Draw a still head?

Back 380

Front 381

Draw a receiver?

Back 381

Front 382

What piece of apparatus does this show?

Back 382

Round bottom or pear shaped flask

Front 383

What piece of apparatus does this show?

Back 383

Screw tap adaptor

Front 384

What piece of apparatus does this show?

Back 384

Condenser

Front 385

What piece of apparatus does this show?

Back 385

Still head

Front 386

What piece of apparatus does this show?

Back 386

Receiver

Front 387

Describe the speed of organic reactions at room temperature?

How can the rate of reaction be increased?

Back 387

They occur slowly

By heating to overcome the activation energy

Front 388

How do you prepare an organc liquid without boiling off the solvent, reactants or products?

Back 388

Heating under reflux

Front 389

Define reflux?

Back 389

The continual boiling and condensing of a reaction mixture back to the orginal container to ensure that the reaction takes place without the contents of the flask boiling dry

Front 390

Define the term primary?

Back 390

On a carbon atom at the end of a chain

Front 391

Desfine the term saturated?

Back 391

Containing single bonds only

Front 392

Define the term saturated hydrocarbon?

Back 392

A hydrocarbon with single bonds only

Front 393

Define the term secondary>

Back 393

On a carbon atom to which two carbon chains are attached

Front 394

Define the term secondary alcohol?

Back 394

Ab alcohol in which the -OH group is attached to a carbon atom that is attached to two carbon chains and one hydrogen atom

Front 395

Define the term secondary alcohol?

Back 395

An alcohol in which the OH group is attached to a carbon atom that is attached to two or three hydrogen atoms

Front 396

Define the term propagation?

Back 396

The steps that continue a free radical reaction, in which a radical reacts with a reactant molecule to form a new molecule and another radical, causing a chain reaction

Front 397

What aooaratus do you need to heat under reflux?

Back 397

1. Round bottom or pear shaped flask

2. Condenser

3. Rubber tubing

4. Stand and clamp

5. Heat source (usually a bunsen burner)

Front 398

Draw the reflux set up?

Back 398

With bunsen burner and tripod

Front 399

If a reflux reaction is to be carried out at below 100 degrees, what should be used?

Back 399

A water bath

Front 400

Why is a bunsen burner often used in a reflux reaction?

Back 400

To heat the reaction mixture at a fixed temperature

Front 401

Why should a heating mantle be used when heating flammable liquids?

Back 401

So that there are no naked flames present which provides an added level of safety should any of the apparatus leak or crack

Front 402

Describe when and why anti-bumping granules are added to the liquid in a reflux reaction?

Back 402

They are added before the flask is heated so that the contents will boil smoothly. If the granules are not used, large bubbles form at the bottom of the liquid and make the glassware vibrate or jump violently

Front 403

Describe setting up the apparatus for a reflux reaction?

Back 403

1. The flask is clamped by its neck

2. Add the reaction mixture and anti-bumping granules to the flask

3. Apply a thin layer of grease to the ground-glass joint on the condenser and place it carefully into the flask, rotating it back and forth to get a good seal

Front 404

During reflux what position is the condenser in?

Back 404

In the upright position

Front 405

Why should condesners be clamped only loosely?

Back 405

As the glass outer jacket is very fragile and easily broken

Front 406

Why should you not put a stopper in the top of acondenser>

Back 406

You would have a closed system and pressure would build up inside as the heated air expands which could result in the apparatus expolding

Front 407

Describe how water is moved through the condenser?

Back 407

1. Rubber tubing is used to connect the inlet of the condenser to the tap and the outlet to the sink

2. Water always enters the condenser at the bottom and leaves at the top to ensure that the outer jacket is full

Front 408

What does, in refulx, continually boiling a liquid mean?

Back 408

Volatile components cannot escape and the flask does not boil dry. This is because the vapour from the mixture rises up and the inner tube of the condenser untill it meets the outer jacket containing cold water. This vapour then condenses and drips back into the flask.

Front 409

What is a common method used to separate a pure liquid from it impurities?

Back 409

Distillation

Front 410

Why made the products of a reflux reaction need to be distilled?

Back 410

To remove any crude liquid or solid products present in the flask to purify it and remove any by-products and remaining reactants

Front 411

What apparatus do you need to carry out a distliiation?

Back 411

1. Round bottom or pear shaped flask

2. Condenser

3. Rubber tubing

4. Heat source

5. Stand and clamp

6. Screw-cap adaptor

7. Receiver adaptor

8. Still head

9. Thermometer

Front 412

Draw the distillation setup?

Back 412

Front 413

Describe the process of setting up the apparatus for distillation?

Back 413

1. Flask is clmaped by the neck

2. Still-head connected to the flask

3. Joints are greased so that the apparatus come apart easily

4. Second clamp placed around the receiver adaptor at the point at which it is attached to the condenser

Front 414

Describe the still-head adaptor?

Back 414

It is T shaped and has two ground glass joints, one to fit the screw-cap adaptor and one to fit the condenser

Front 415

Why in distillation in the second clamp placed around the receiver adaptor at the point at which it is attached to the condenser?

Back 415

To remove the need to clamp the condenser as it will be supported sufficiently at both ends

Front 416

What is the liquid produced from distillation called?

Back 416

The distillate

Front 417

What is used to collect the distillate, what does this mean?

Back 417

A flask is used to collect it so that the distillation apparatus are not completelye airtight

Front 418

What happens once the apparatus for distillation is set up and you start to boil it?

Back 418

The different liquids in the mixture will have different boiling points. The liquid with the lowest boiling point is the most volatile and boil first. The vapour moves out of the flask, up into other part of the apparatus, leaving behind the less volative components. When the vapours reach the cold condeser they condense and becoe a liquid, this then drips into the flask

Front 419

When preparing samples of orgaic liquids, what may be obtained with the product?

Back 419

Water

Front 420

If water is obtained when preparing samples of organic liquids what would you see?

Back 420

Two layers to liquid inside your collection flask, one the organic layer and one the water layer

Front 421

How do you indentify in a sample of an organic water that has produced water, which is the water?

Back 421

You add more water to your mixture, the layer that gets bigger is the aqueous layer

Front 422

How do you separate water from a sample of an organic liquid?

Back 422

1. Ensure that tge tap of the separating finnel is closed

2. Pour in the mixture of liquids and place a stopper in the top of the funnel, inverting to mix the contents

3. Allow the layers to settle

4. Add some water to see which layer increases in volume - this is the aqueous layer

5. Place a conical flask under the separating funnel, remove the stopper and open the tap until the whole of the lower layer has left the funnel

6. place a second conical flask under the separating funnel to collect the other layer

7. Label your flasks

Front 423

What might happen to samples of organic liquids repeared using acids?

Back 423

They may contain acid impurities

Front 424

How are acid impurities removed from samples of organic liquids? (method)

Back 424

1. By adding aqueous sodium carbonate and shaking the mixture in the separating funnel.

2. Any acid present will react with the sodium carbonate, releasing carbon dioxide gas.

3. The tap needs to be opened slowly, holding the stoppered separating funnel upside down to release any gas pressure that may build up.

4. The aqueous sodium carbonate layer is removed and the organic layer washed with water before running both layers off into separate flasks

Front 425

Why is there a need to dry the organic product produced from distillation/reflux?

Back 425

Because there might be some water left in the organic product

Front 426

How are traces of water removed from an organic product?

Back 426

BY adding a drying agent

Front 427

What is a drying agent?

Back 427

An anhydroys inorganic salt that readily takes up water to become hydroated

Front 428

What are the most common drying agents?

Back 428

1. Anhydrous calcium chloride

2. Anhydrous calcium sulfate

3. Anhydrous magnesium sulfate

Front 429

What is the formula of anhydrous calcium chloride, what is its use?

Back 429

CaCl2

Drying hydrocarbons

Front 430

What is the formula of anhydrous calcium sulfate, what is its use?

Back 430

CaSO4

General drying

Front 431

What is the formula of anhydrous magnesium sulfate, what is its use?

Back 431

MgSO4

General drying

Front 432

Describe the procedure for drying an organic liquid?

Back 432

1. Add the organic liquid to a conical flask

2. Using a spatula, add some of the drying agent to the liquid and gently swirl the contents to mix

3. Place a stopper on the flask to prevent the product evaporating and leave for 10 minutes

4. If the solid has all stuck together there is still some water present, add more drying agent until some solid is dispersed in the solution as a fine powder

5. Decant the liquid from the solid into another flask. If the liquid is dry it should be clear

Front 433

Why is redistillation sometimes needed?

Back 433

Because sometimes, orgaic liquids have boiling points that are relatively close together so your prepared sample may still contain some organic impurities

Front 434

Describe the process of redistillation?

Back 434

1, The distillation apparatus are clearned and dried and set up again so that a second distillation can be carried out

2. This time only collect the product with the boiling point of the compound you are trying to make

3. The narrower the boiling range the purer the product

Front 435

What elements do the haloalkanes contain?

Back 435

Carbon, hydrogen and at lest one halogn

Front 436

What are aliphatic haloalkanes?

Back 436

In which the halogen is joined to a straight or branched carbon chain

Front 437

What type of haloalkane is this?

Back 437

A primary haloalkane

Front 438

What type of haloalkane is this?

Back 438

A secondary haloalkane

Front 439

What type of haloalkane is this?

Back 439

A tertiary haloalkane

Front 440

In haloalkanes, what is the prefix for each of these halogens...

1. F

2. Cl

3. Br

4. I

Back 440

1. Fluoro-

2. Chloro-

3. Bromo-

4. Iodo-

Front 441

Name the bond in haloalkanes that is polar?

Back 441

The carbon-halogen bond

Front 442

Describe why the carbon-halogen bond in haloalkanes is polar?

Back 442

The halogen atoms are more electronegative than carbon atoms. The electron pair in the carbon-halogen bond is therefore closer to the halogen atom that the carbon atom. The carbon-halogen bond is polar

Front 443

Define aromatic?

Back 443

Containing one or more benzene rings

Front 444

Define cis-trans isomerism?

Back 444

A special type of E/Z isomerism in which there are two non-hydrogen groups and two hydrogen atoms around the C=C double bond. the cis isomer (Z) has H atoms on each carbon on the same side wholst the trans isomer (E) has H atoms on each carbon on different sides

Front 445

Define the term diproportionation?

Back 445

A redox reaction in which the same element is both oxidised and redcued

Front 446

Define E/Z isomerism?

Back 446

A type of stereoisomerism in which different groups attached to each C=C double bond may be arranged differently in space because of the restricted rotation of the C=C bond

Front 447

Define electrophiliic substitution?

Back 447

A type of substituton reaction in which an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond

Front 448

Define an elimination reaction?

Back 448

The removal of a molecule from a saturated molecule to make an unsaturated molcule

Front 449

Define fractional distillation?

Back 449

The separation of components in a liquid mixture by their different boiling points into fractions with different compositions

Front 450

Define herteolytic fission?

Back 450

The breaking of a covalent bond with both of the bonded electrons going to each atom, forming a cation and an anion

Front 451

Define homolytic fission?

Back 451

The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals

Front 452

Define initiation?

Back 452

The first stage in a radical reaction in which radicals starts when a covalent bond is broken by homolytic fission

Front 453

Define anucloephile?

Back 453

An atom (or group of atoms) which is attracted to an electron deficient center or atom, where it donates a pair of electrons to form a new covalent bond

Front 454

Define nucleophilic substitution?

Back 454

A reaction in which a nucleophile is attracted to an electron deficient carbon atom and replaces an atom or group of atoms on the carbon atom

Front 455

Define a pi-bond?

Back 455

A bond formed by the sideways overlap of two p-orbitals with the electron density above the plane of the bonding atoms

Front 456

Define a radical?

Back 456

A species with an unpaired electron

Front 457

Define the term termination?

Back 457

The step at the end of a radical substituion when two radicals combine to form a molecule

Front 458

Define a tertiay alcohol?

Back 458

An alcohol in which the -OH group is attached to a carbon atom that is attached to three carbon atoms and no hydrogen atoms

Front 459

Define the term unsaturated?

Back 459

Containing multiple C=C bonds

Front 460

Give three examples of nucleophiles?

Back 460

1. Hydroxide ions

2. Water molecules

3. Ammonia

Front 461

What happens when a haloalkane reacts with a nucleophile?

Back 461

The nuceltophile replaces the halogen in a substitution reaction. A new compound is produced containing a different functional group.

Front 462

Describe nucleophilic substituion (general) in haloalkanes?

Back 462

1. Haloalkane reacts with a nucleophile

2. The nucleophile replaces the halogen in a substitution reaction

3. A new compound is produced containing a different functional group

Front 463

What is the mechanism for the reaction of an haloalkane and water?

Back 463

Nucleophilic substitution

Front 464

What is the mechanism for the reaction of an haloalkane and hydroxide ions?

Back 464

Nucleophilic substitution

Front 465

What is the mechanism for the reaction of an haloalkane and ammonia ions?

Back 465

Nucleophilic substitution

Front 466

Describe the reaction of primary haloalkanes in nucelophilic substitution (general)?

Back 466

They undergo substitution reactions with a variety or different nucleophiles to produce a wide range of different compounds

Front 467

What is hydrolysis?

Back 467

It is a chemical reaction involving water or an aqueous solution of a hydroxide that causes the breaking of a bond in a molecule. This results in the molecule being split into two products

Front 468

What happens (generally) in the hydrolysis of a haloalkane?

Back 468

The halogen atom is replaced by an -OH group. This is an example of a nucleophillic substiution reaction.

Front 469

Describe the stages of nucelophilic addition in hydrolysis of haloalkanes?

Back 469

1.The nucleophile (OH^-) approached the carbon atom attached to the halogen on the opposite side of the molecule from the halogen

2. A lone pair of electrons on the hydroxide ion is attracted and donated to the delta + carbon atom

3. A new bond is formed between the oxygen atom of the hydroxide ion and the carbon atom

4. The carbon-halogen bond breaks by heterolytic fission

5. The new organic product is an alcohol. A halide ion is also formed

Front 470

Why does the nucelophile (OH^-) in hydrolysis of haloalkanes approach from the opposite side of the molecule to the halogen atom?

Back 470

To minimisre repulsion between the nucleophile and the delta negative halogen atom

Front 471

Draw the mechanim for the hydrolysis of chloroethane?

Back 471

Front 472

Describe one way that haloalkanes can be converted to alcohols?

Back 472

Using aqueous sodium hydroxide

Heated under reflux

Front 473

Why is the reaction of haloalkanes to form alcohols done under the conditions it is?

Back 473

It is heated under reflux

Very slow at room temperature so the mixture is heated to obtain a good-yield of the product

Front 474

Draw the mechanism for the hydrolysis of 1-bromobutane?

Back 474

Front 475

Draw the displayed formula for the hydrolysis of 1-bromobutane?

Back 475

Front 476

In hydrolysis of haloalkanes what bond is broken?

What substitutes what?

Back 476

The carbon-halogen bond

The -OH group replaces the halogen in the haloalkane

Front 477

What does the rate of hydrolysis of haloalkanes depend upon?

Back 477

The strenght of the carbon-halogen bond in the haloalkane

Front 478

Draw a bar chart for the trend in strenght of the carbon-halogen bond in haloalkanes for the first four halogens?

Back 478

Front 479

What does the rate of hydrolysis of haloalkanes depend upon?

Back 479

The strenth of the carbon-halogen bond in the haloalkane

Front 480

What is the strongest carbon-halogen bond?

What is the weakest?

Make a comparison statement?

Back 480

C-F

C-I

Less energy is required to break the C-I bonds

Front 481

Using bond enthalpies of the carbon-halogen bond what can be predicted for hydrolysis reactions?

Back 481

1. Iodoalkanes react faster than bromoalkanes

2. Bromoalkanes react faster than chloroalkanes

3. Fluoroalkanes are unreactive as a large quantity of energy is required to break the C-F bond

Front 482

What symbol can be used to represent any of the halogens?

Back 482

X

Front 483

What does 'X' represent in display formula?

Back 483

Any of the halogens

Front 484

Describe, what must be added, and why, when measuring the rate of hydrolysis of haloalkanes because haloalkanes are insoluble in water?

Back 484

An ethanol solvent must be added so that the water and the haloalkane mix and produce a single solution rather than two layers

Front 485

Describe the expermient to comapre the rates of hydrolysis of 1-chlorobutane, 1-bromobutane and 1-iodobutane?

Back 485

1. Set up three test tubes with 1cm^3 of ethanol and two drops of the appropriate haloalkane

2. Stand the test tubes in a water bath at 60 degrees

3. Place a test tube containing 0.1 mol dm^-3 silver nitrate in the water bath, until all of the tubes have reached a constant temperature

4. Add 1cm^3 of the silver nitrate quickly to each of the test tubes. Immediately start a stop clock

5. Observe the test tubes for five minutes and record the time taken for the precipitate to form

Front 486

What should be the observation from the hydrolysis of 1-chlorobutane using silver ions?

Back 486

A white precipitate froms very slowly

Front 487

What should be the observation from the hydrolysis of 1-bromobutane using silver ions?

Back 487

A cream precipitate froms solwer than with 1-iodobutane but faster than with 1-chlorobutane

Front 488

What should be the observation from the hydrolysis of 1-iodobutane using silver ions?

Back 488

A yellow precipitate froms rapidally

Front 489

Why, when measuring the rate of hydrolysis of 1-chlorobutane using a precitate of silver halide, does it have the slowest rate of reaction in comparison to 1-bromobutane and 1-iodobutane?

Back 489

The compound with the slowest rate of reaction is the one that has the strongest carbon-halogen bond due to having the largest difference in electronegativity. 1-Chlorobutane reacts the slowest and the C-Cl bond is the strongest. 1-Iodobutane reacts fastest and the C-I bond is the weakest

Front 490

Draw an arrow indicating which direction the reactivity of these compounds increases?

Back 490

Front 491

What is an organohalogen compound?

Back 491

Organohalogen compound, any of a class of organic compounds that contain at least one halogen (fluorine [F], chlorine [Cl], bromine [Br], or iodine [I]) bonded to carbon.

Front 492

Give examples of uses of organohalogens?

Back 492

1. Pesticides

2. General solvents

3. Dry cleaning solvents

4. Making polymers

5. Flame retardants

6. Refridgerants

Front 493

Why are organohalogens a concern?

Back 493

Because they are rarley found in nature, and so they are not broken down naturally in the enviornment

Front 494

Where is the ozone layer found?

Back 494

At the outer edge of the stratosphere, at a height that vaires from 10 to 40 km above the Earths surface

Front 495

Describe the proportion of gasses making up the ozone layer?

Back 495

Only a tiny fraction is ozone gas, but this is enough to absorb most of the biologically damaging ultraviolet radiation from the suns rays, allowing only a small amount to reach the Earths surface

Front 496

Describe the function of ozone gas?

Back 496

It absorbs most of the biologically damaging ultraviolet radiation from the sun's rays, allowing only a small amount to reach the Earth's surface

Front 497

What is ultraviolet radiation also called?

Back 497

UV-B

Front 498

What is UV-B most commonly linked to?

Back 498

1. Sunburn

2. More research has been carried out on its harmful effects

Front 499

What is feared to be the result of continual depletion of the ozone layer?

Why is this bad for living organisms?

Back 499

It will allow more UV-B radiation to reach the earths surface

Increased genetic damage and a greater risk of skin cancer

Front 500

What continually occurs in the stratosphere?

Back 500

The ozone is contiunally being formed and broken down by the actions of ultraviolet radiation

Front 501

Describe the steps of the process by which the ozone is continually being formed and broken down by the actions of ultraviolet radiation in the stratosphere?

Back 501

Initially, very high energy UV breaks down oxygen molecules into oxygen radicals: O2 --> 2O

A steady state is set up involving O2 and the oxygen radicals in which ozone forms, and then breaks down:

O2 + O ---><--- O3

Front 502

What is a steady state?

Back 502

An unvarying condition in a physical process

Front 503

What is the formula of ozone gas?

Back 503

O3

Front 504

Describe the rate of formation of ozone and break down of ozone in the stratesphere?

Back 504

The rate of formation and the rate at which it is broken down is the same

Front 505

Describe how huan activity has effected the rate of ozone production?

Back 505

The production and use of chlorofluorocarbons, as upset the delicate equilibrium of the same rate of formation and break down of ozone in the steady state in the statesphere

Front 506

What causes the constant formation and degredation of ozone in the stratesphere?

Back 506

The action of ultraviolet radiation

Front 507

What were, untill recently the most common compounds used in refrigerants, air conditioning units and aerosol propellants?

Back 507

Chlorofluorocarbons (CFCs)

Hydrochlorofluorocarbons (HCFCs)

Front 508

What were Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) most commonly used in untill recently?

Back 508

1. Refrigerants

2. Air conditioning units

3. Aerosol propellants

Front 509

Why are Chlorofluorocarbons (CFCs) very stable?

Back 509

Becasue of the strength of the carbon-halogen bonds within their molecules

Front 510

Describe the science of the ozone depletion?

Back 510

1. Chlorofluorocarbons (CFCs) remain stable untill they reach the stratosphere where they begin to break down

2. The UV radiation provides sufficient energy to break a carbon-halogen bond in CFCs by homolytic fission

2. They form chlorine radicals which catalyse the breakdown of the ozone layer

Front 511

Who were the scientists awarded the nobel peace prize for discovering the ozone depletion?

Back 511

Sherwood and Molina

Front 512

Why is it chlorine radicals that form from CFCs (Chlorofluorocarbons)?

Back 512

Because the C-Cl bond has the lowest bond enthalpy and so is the bond that breaks

Front 513

Describe Chlorofluorocarbons in the troposphere?

Back 513

They have a long residence time. It may take them many years to reach the stratosphere

Front 514

What is the breakdown of Chlorofluorocarbons (CFCs) by radiation called?

Back 514

Photodissociation

Front 515

What is photodissociation?

Back 515

The process by which radiation breaks down Chlorofluorocarbons (CFCs) to form radicals

Front 516

Give the formula of Chlorofluorocarbons (CFCs)?

Back 516

CF2Cl2

Front 517

Give the chemistry of photodissociation?

Back 517

CF2Cl2 --> CF2Cl(radical) + Cl(radical)

Front 518

Describe the chlorine radical fomed from photosissociation?

Back 518

It is a very reactive intermediate. It can react with an ozone molecule, breaking it down into oxygen

Front 519

Describe the propagation steps following the photodissociation of Chlorofluorocarbons (CFCs)?

What is the overall equation?

Back 519

Step 1: Cl(radical) + O3 --> ClO(radical) + O2

Step 2: ClO(radical) + O --> Cl(radical) + O2

O3 + O --> 2O2

Front 520

How many ozone molecules can be broken down by a single Chlorofluorocarbon (CFC) molecule?

Back 520

100000 molecules of ozone

Front 521

Are Chlorofluorocarbons (CFCs) responsible for all ozone-depleting reactions?

Back 521

The simple answer is no, other radicals also catalyse the breakdown of ozone. Nitrogen oxide radicals are formed naturally during lightning strikes and also as a result of aircraft travel in the stratosphere

Front 522

Give the mechanism similar to that involving nitrogen oxide radicals that cuases the breakdown of the ozone?

Overall equation?

Back 522

Propagartion 1: NO (radical) + O3 --> NO2(radical) + O2

2 NO2(radical) + O --> NO(radical) + O2

O3 + O --> 2O2

Front 523

What happened to Chlorofluorocarbons (CFCs)?

Back 523

1. A protocol was signed which introduced steps for their removel in all by a limited number of products where no sustainable alternative can be found

2. Coolants have been developed that use hydrocarbons, ammonia and carbon dioxide

Front 524

Describe claims of Apple and Dell?

Back 524

They claim to have reduced or eliminated enviornmentally damaging flame retardants from their products and to have stopped using the organohalogen polymer PVC

Front 525

Give one Organohalogen under close scrutiny currently and describe them?

Back 525

Brominated flame retardants (BRFs), organobromine compounds commonly used in electronics, such as in circuit boards, outer coverings and cables to reduce flammability of products. They are suspected of being toxins that may interfer with the human endocrine system

Front 526

Give the functional groups in these organic molecules?

Back 526

Haloalkane, ketone and aldehyde

Front 527

Give the functional groups in these organic molecules?

Back 527

Alcohol, alkene and carboxylic acid

Front 528

What are the conditions for the reaction of an alkane to a haloalkane?

Back 528

Halogen/UV light

Front 529

What are the conditions for the reaction of an alkene to an alkane?

Back 529

Hydrogen and a nickel catalyst

Front 530

What are the conditions for the reaction of an alkene to a haloalkane?

Back 530

Hydrogen halide

Front 531

What are the conditions for the reaction of an haloalkane to an alcohol?

Back 531

NaOH (aq) under reflux

Front 532

What are the conditions for the reaction of an alcohol to a haloalkane?

Back 532

Sodium halide and H2SO4

Front 533

What are the conditions for the reaction of an alcohol to a alkene?

Back 533

Concentrated H2SO4

Front 534

What are the conditions for the reaction of an alkene to an alcohol?

Back 534

HsO (g) and a H3PO4 catalyst

Front 535

What are the conditions for the reaction of an primary alcohol to a carboxylic acid?

Back 535

Kr2Cr2O7/H2SO4 under reflux

Front 536

What are the conditions for the reaction of an primary alcohol to a aldehyde?

Back 536

Kr2Cr2O7/H2SO4 under distillation

Front 537

What are the conditions for the reaction of an alcohol to a ketone?

Back 537

Kr2Cr2O7/H2SO4 under reflux

Front 538

How do you go from an alcohol to an alkane?

What are the conditions for each step?

Back 538

Alcohol --> Alkenes --> Alkanes

1. Dehydration with concentrated H3PO4/H2SO4

2. Hydrogen and a nickel catalyst

Front 539

How do you polymerise an alcohol?

What are the conditions for each step?

Back 539

Alcohol --> Alkenes --> Polymers

1. Dehydration with concentrated H3PO4/H2SO4

2. High temperature, pressure and a catalyst

Front 540

How do you go from an alkane to an alkene?

What are the conditions for each step?

Back 540

Alkanes --> Haloalkanes --> Alcohols --> Alkenes

1. UV light

2. Sodium hydroxide under reflux

3.Concentrated H2SO4/H2PO4

Front 541

How do you go from an alkene to a ketone?

What are the conditions for each step?

Back 541

Alkenes --> Alcohols --> Ketones

1. H2O (steam) with a H3PO4 catalyst

2. K2Cr2O7/H2SO4 under reflux

Front 542

How do you go from an alkene to a carboxylic acid?

What are the conditions for each step?

Back 542

Alkene --> Alcohol --> Carboxylic acid

1. Steam (H2O) with a H3PO4 catalyst

2. K2Cr2O7/H2SO4 under reflux

Front 543

How do you go from an alkene to an aldehyde?

What are the conditions for each step?

Back 543

Alkene --> Alcohol --> aldehyde

1. Steam (H2O) with a H3PO4 catalyst

2. K2Cr2O7/H2SO4 under distillation

Front 544

How do you go from an alkane to a ketone?

What are the conditions for each step?

Back 544

Alkane --> Haloalkane --> Alcohol --> Ketone

1. UV light

2. Sodium hydroxide under reflux

3. K2Cr2O7/H2SO4 under reflux

Front 545

How do you go from an alkane to a carboxylic acid?

What are the conditions for each step?

Back 545

Alkane --> Haloalkane --> Alcohol --> Carboxylic acid

1. UV light

2. Sodium hydroxide under reflux3. K2Cr2O7/H2SO4 under reflux

Front 546

How do you go from an alkane to an aldehyde?

What are the conditions for each step?

Back 546

Alkane --> Haloalkane --> Alcohol --> Ketone

1. UV light

2. Sodium hydroxide under reflux

3. K2Cr2O7/H2SO4 under distillation

Front 547

How do you go from an haloalkane to a ketone?

What are the conditions for each step?

Back 547

Haloalkane --> Alcohol --> Ketone

1. Sodium hydroxide under reflux

2. K2Cr2O7/H2SO4 under reflux

Front 548

How do you go from an haloalkane to a carboxylic acid?

What are the conditions for each step?

Back 548

Haloalkane --> Alcohol --> carboxylic acid

1. Sodium hydroxide under reflux

2. K2Cr2O7/H2SO4 under reflux

Front 549

How do you go from an haloalkane to a ketone?

What are the conditions for each step?

Back 549

Haloalkane --> Alcohol --> Aldehyde

1. Sodium hydroxide under reflux

2. K2Cr2O7/H2SO4 under distillation

Front 550

How do you get from a haloalkanes to an alkene?

What are the conditions for each step?

Back 550

Haloalkane --> Alcohol --> Alkene

1. Sodium hydroxide under reflux

2. Concentrated H3PO4/H2SO4

Front 551

Define the term target molecules?

Back 551

The compound that a chemist is attempting to prepare by organic synthesis

Front 552

Describe how a traget molecule can be prepared in most simple synthesis?

Back 552

The target molecule can be obtained by reacting a readily avalibale starting material with a readily avaliable reagent in one step reaction

Front 553

Describe most organic synthesis to achieve a target molecule in comparison to simple synthesis?

Back 553

In most cases it is not straightforward. Some synthese require many steps to change functional groups of add carbon atoms to the chain length in order to obtain the target molecule

Front 554

List two things that you could change about a molecule when trying to achieve a target molecule in organic synthesis?

Back 554

1. Functional groups

2. Length of carbon chain

Front 555

What are the three things you need to do when converting a starting molecule into the target molecule?

Back 555

1. Identify the functional groups in your strating and target molecule

2. Identify the intermediate that links the starting and target molecule

3. State the reagents and conditions for each step

Front 556

State the reganets and the conditions for the two stge synthesis of propanal from 1-chloropropane?

Back 556

Starting Molecule: Haloalkane

Intermediate: Alcohol

Target molecule: Aldehyde

Reagents 1: NaOH (aq) under Reflux

Reagents 2: Potassium dichromate and sulfuric acid under distillation

Front 557

State the reagents and conditions for the synthesis of butanone from but-2-ene?

Back 557

Starting Molecule: Alkene

Intermediate: Alcohol

Target Molecule: Ketone

Reagents 1: H2O (Steam) with acid catalyst

Reagents 2: K2Cr2O7/H2SO4 + Reflux

Front 558

What happens if the starting molecule you are converting to a target molecule has more than one functional group?

Back 558

You have to remove/convert both of these

Front 559

What do some people believe that the natural resources of our planet provide?

What limits us from these?

Back 559

Cures for every disease or illness

Time and limits of knowledge from finding a cure for every illness

Front 560

What is used for the treatment of fever and pain?

Why?

What was developed from this?

Back 560

The bark of the willow tree

Contains Salicylic acid

Aspirin

Front 561

What is the bark of willow tree used for?

Back 561

Treatment of pain and fever

Front 562

What is obtained from the bark of pacific yew trees?

What is it used for?

Back 562

Paclitaxel

Taxel, used as an anti-cancer drug

Front 563

Describe the demand for taxol?

Therefore, what is being done?

Back 563

It is much higher than the amounts that can be obtained from yew bark

Chemists synthesise taxol from more readily avalibale substance

Front 564

What is the use of ibyprofen?

Back 564

Anti-inflammatory drug

Front 565

Draw a map of organic synthesis?

Back 565

Front 566

What can mass spectra be used for?

Back 566

1. Identify the molecular mass of an organic compound

2. Gain further information about its structure

Front 567

What happens immediatley when an organic compound is placed in a mass spectrometer?

Back 567

It loses an electron and forms a psoitive ion, the molecular ion

Front 568

Define the molecular ion?

Back 568

The positive ion formed in mass spectrometry when a molecule loses an electron

Front 569

What does a mass spectrometer detect?

Back 569

The mass to charge ratio of the molecular ion which gives the molecular mass of the compound

Front 570

Give the chemical equation for the formation of the molecular ion of propan-1-ol?

Back 570

CH3CH2CH2OH--. CH3CH2CH2OH^+ + e^-

Front 571

How do you find the molecular mass from a spectrum?

Back 571

You locate the molecular ion peak

Front 572

What is the symbol for the molecular ion peak?

Back 572

M^+

Front 573

Which peak is the molecular ion peak?

Back 573

It is the clear peak at the highest m/z value on the right hand side of the mass spectrum

Front 574

What is the M + 1 peak?

Back 574

It is a very small peak one unit after the M^+ peak. This exists because 1.1% of carbon is present as the carbon-13 isotope (In the molecule as it is organic)

Front 575

Describe the M+1 peak for propan-1-ol?

Back 575

1. Has molecular mass of 60

2. Small proportion of the alcohol molecules will contain an atom of 13C and thus have a molecular mass of 61

3. This gives the small M+1 peak

Front 576

What is fragmentation?

Back 576

The process by which in the mass spectromeyer some molecular ions breaks down into smaller pieces known as gragments

Front 577

Describe what the background peaks in the mass specturm are caused by?

Back 577

Fragment ions

Front 578

What are fragment ions?

Back 578

They are ions formed from the breakdown of the molecular ion

Front 579

What two things does the simplest fragmentation (fission) break a molecule down into?

Back 579

Into two species

1. A positively charged fragment ion

2. A radical

Front 580

Describe the detection ofions in the mass spectrometer?

Back 580

Any uncharged radicals are not detected

Front 581

What specificially does the mass spectrometer detect?

Back 581

Any positive ions formed

Front 582

Describe how propan-1-ol could break down to form a CH2OH^+?

Give the word equation?

Back 582

CH3CH2CH2OH^+ --> CH2OH^+ + CH3CH2(radical)

Molecular ions --> fragment ion + radical

Front 583

Describe why the mass spectrum of each compound is unique?

What does this mean?

Back 583

Moleculeds will all fragment in slightly different ways depending on their structures

Mass spectra can be used to identify molecules

Front 584

Name four fragment ions?

Back 584

1. CH3^+

2. C2H5^+

3. C3H7^+

4. C4H9^+

Front 585

What is the m/z for the fragment ion CH3^+?

Back 585

15

Front 586

What is the m/z for the fragment ion C2H5^+?

Back 586

29

Front 587

What is the m/z for the fragment ion C3H7^+?

Back 587

43

Front 588

What is the m/z for the fragment ion C4H9^+?

Back 588

57

Front 589

Give the main features of the spectra?

Back 589

1. Molecular ion peak at m/z = 46

2. Small M+1 peak at m/z = 47

3. A number of fragment peaks

Front 590

Identify some of the fragment ions here?

Back 590

1. peak at m/z = 15 for CH3+

2. peak at m/z = 29 for C2H5^+

Front 591

Name one use of drug testing?

Back 591

In sports

Front 592

How is mass spectra used to test for drugs?

Back 592

It can be used to test urine samples

Front 593

Give one drug used illegally by some atheletes that is believed to increae the devlopment of muscle?

Back 593

Clenbuterol

Front 594

Describe Clenbuterol?

Back 594

1. Increase development of muscle

2. Performance enhancing drug

3. Banned in athletic competitions

Front 595

What do some atheletes who have tested positive for Clenbuterol say as an excuse?

Why is this discredited?

Back 595

They have eaten contaiminated meat as it has been used to increase yields in livestock production

It is banned for use on cattle in both the USA and much of Europe

Front 596

What are the two common ways that ethanol is industrially produced?

Back 596

1. Hydration of ethane

2. Fermentation of sugars

Front 597

Give the formula for the hydration of ethane?

Back 597

C2H4 + H2O --> C2H5OH

Front 598

Give the formula for the fermentation of sugars to produce ethane?

Back 598

C6H12O6 --> 2C2H5OH + 2CO2

Front 599

What is the function of the still head adaptor?

Back 599

Used in distillation assemblies for connecting flasks to condenser and the upper socket is designed to accept thermometer either via screw head adapter

Front 600

What is the function of the screw head adaptor?

Back 600

Ideal for incorporating thermometers into Quick fit jointed glassware assemblies

Front 601

Explain why the straight chain isomer of C10H22 is converted by the petroleum industry into its branched chain isomers?

Back 601

1. Branched chains have more efficient combustion

2. Easier to combust

3. They burn better

4. More efficient fuel

Front 602

Use an equation to show how NO is formed within an engine?

Back 602

N2 + O2 --> 2NO

Front 603

What role does NO and Cl2 have in the role of ozone depleition?

Back 603

They are catalysts

Front 604

What does ozone do to UV?

Back 604

It absorbs it

Front 605

What is the name of the process used to convert long chain alkanes into more useful shorter chain alkenes?

Back 605

Cracking

Front 606

Name two types of degradable polymers?

Back 606

1. Biodegradable polymers

2. Photodegradable polymers

Front 607

Describe three enviornmental problems of NO?

Back 607

1. Cause acid rain

2. Photochemical smog

3. Low level ozone

Front 608

Give enviornmental problems of CO?

Back 608

CO is toxic as reduces the capacity of blood to carryoxygen

Front 609

NO and CO react to form two less harmful gases. Name the two gases formed and write an equation?

Back 609

Makes nitrogen and carbon dioxide

2CO + 2NO --> N2 + 2CO2

Front 610

What type of overlap is it that forms p-bonds?

Back 610

Sideways

Front 611

Where are pi-bonds formed?

Back 611

Forms π-orbital or π-bond above and below plane ofmolecule

Front 612

Explain why E/Z isomerism is shown in some alkenes?

Back 612

1. Double bond does not rotate

2. Each carbon atom of double bond is bonded to two different groups

Front 613

Construct an equation to show the formation of cyclohexane from hexane?

Back 613

C6H14 --> C6H12 + H2

Front 614

Name some harmful gases produce when PTFE (polyflurotetraethane) is burnt?

Back 614

1. Phosgene

2. Toxic gases

3. Dioxins

Front 615

Describe the energy possessed by covalent bonds?

Back 615

They possess energy and vibrate naturally about a central point

Front 616

Why do covalent bonds vibrate?

Back 616

Because they possess energy

Front 617

Where about do covalent bonds vibrate?

Back 617

Around a central point

Front 618

Whe does the amount a covalent bond vibrates increase? NOT IR

Back 618

With increasing temperature

Front 619

What does covalent bonds vibrating mean (apart from that they have energy) for the atoms?

Back 619

The atoms in molecules are therefore in constant motion

Front 620

What makes covalent bonds vibrate, bend or stretch more?

Back 620

The absorbtion of infrared radiation

Front 621

What happens when covalent bonds absorb infrared radiation?

Back 621

The covalent bonds bend, vibrate or stretch more

Front 622

Describe one type of vibration in a covalent bond, a stretch?

Back 622

1. Rhythmic movement along the line between the atoms

2. The distance between the two atomic centres increases and decreases

Front 623

What are the two types of vibration of covalent bonds?

Back 623

1. A stretch

2. A bend

Front 624

Describe one type of vibration in a covalent bond, a bend?

Back 624

1. Results in the change in a bond angle

Front 625

What effect does this show infrared radiation to have on covalent bonds?

Back 625

Bond angle decreases as the bonds in the molecule bend

Front 626

What effect does this show infrared radiation to have on covalent bonds?

Back 626

Bond angle increases as the bonds in the molecule bend

Front 627

What effect does this show infrared radiation to have on covalent bonds?

Back 627

Bond angle decreases as the bonds in the molecule bend

Front 628

What effect does this show infrared radiation to have on covalent bonds?

Back 628

Bond angle increases as the bonds in the molecule bend

Front 629

What effect does this show infrared radiation to have on covalent bonds?

Back 629

A bond in a molecule can stretch so that the distance between the atomic centres changes

Front 630

What effect does this show infrared radiation to have on covalent bonds? All 4 centers a part of the one molecule, not a before/after

Back 630

A bond in a molecule can stretch so that the distance between the atomic centres changes

Front 631

What effect does this show infrared radiation to have on covalent bonds?

Back 631

A bond in a molecule can stretch so that the distance between the atomic centres changes

Front 632

Draw a bond angle decreasing as bonds in a molecule can bend?

Back 632

Front 633

Draw a bond angle increasing as bonds in a molecule can bend?

Back 633

Front 634

Draw a bond stretching so that the distance between the atomic centres changes?

Back 634

Front 635

What two factors effect the amount a bond stretches or bends?

Back 635

1. The mass of the atoms in the bond

2.The strength of the bond

Front 636

What effect does the mass of the atoms in a bond have on the amount a bond stretches or bends?

Back 636

Heavier atoms vibrate more slowoly than lighter atoms

Front 637

What effect does the strength of the bond have on the amount a bond stretches or bends?

Back 637

Stronger bonds vibrate faster than weaker bonds

Front 638

What radiation can any particular bond absorb?

Back 638

Radiation that has the same frequency as the natural frequency of the bond

Front 639

Why are wavenumbers used instead of vibration frequency values>

Back 639

Because they are very large and so wavenumbers are o a more convenient scale

Front 640

Describe the relationship between wavenumber and frequency?

Back 640

Wavenumber is proportiona to frequyency

Front 641

What is the infrared radiation wavenumber range?

Back 641

200 cm^-1 to 4000cm^-1

Front 642

What is spectroscopy?

Back 642

Spectroscopy is the study of the interaction between matter and electromagnetic radiation

Front 643

Describe the general relationship between infrared radiation and atmospheric gases?

Back 643

Much of the suns visible and ifrared radiation is relatively unaffected by atomspheric gases. The radiation passes through the atmosphere to the Earths surface where most of it is absorbed

Front 644

Describe the deviation from the general relationship between infrared radiation and atmospheric gases?

Back 644

Most radiation is abrobed by the earth surface. However, some is re-emmited from the Earths surface in the form of longer wavelength infrared radiation

Front 645

Name three greenhouse gases?

Back 645

1. Water vapour

2. Carbon dioxide

3. Methane

Front 646

Describe greenhouse gases and which wavelength of infrared radaiton they absorb?

Back 646

They absorb the longer-wavelength ifrared radiation because it has the same frequency as the natural frequency of their bonds

Front 647

Describe greenhouse gases and emitting infrared radiation?

Back 647

The vibrating bonds in these molecules re-emit this energy as radiation that increases the temperature of the atmosphere close to the Earyths surface, leading to global warming

Front 648

What are the three most abundant greenhouse gases in the atmosphere?

Back 648

1. Water vapour

2. Carbon dioxide

3. Methane

Front 649

How is the government trying to reduce emissions of carbon dioxide?

Back 649

Incentives are avaliable to householders for reducing pollution and for converting to renewable sources of energy that do not emit carbon dioxide

Front 650

How do chemistrys identify functional groups present in organic molecules?

Back 650

Infrared spectroscopy

Front 651

Describe the process of infrared spectroscopy?

Back 651

1. Sample is placed inside an IR spectrometer

2. Beam of IR radiation in the range 200-4000cm^-1 is passed through the sample

3. The molecule absorbs some of the IR frequencies and the emerging beam of radiation is analysed to identify the frequencies that have been absorbed by the sample

4. The IR spectrometer is connected to a computer that plots a graph of transmittance against wavenumber

Front 652

What are the dips in the graph of transmittance against wavenumber (IR Radiation) called?

Where are they observed

Back 652

Peaks

At a wavenumber that can be related to a particular bond in the molecule

Front 653

What is found below 1500cm^-1 in the graph of transmittance against wavenumber (IR radiation)?

Back 653

The fingerprint region of the spectrum

Front 654

What does the fingerprint region of the spectrum contain?

Back 654

Unique peaks which can be used to identify the particular molecule under investigation

Front 655

What would you use to idenfity the particular molecule under investigation form the fingerprint region?

Back 655

Using computer software or by physically comparing the spectrum to booklets of published spectra

Front 656

Why is it diffiult to predict the certaintiy of functional groups from a peak in the fingerprint region?

Where are they easier to predict?

Back 656

Because they are not very clearer

Everywhere outside ths region

Front 657

In IR spectra what do all organic compounds produce?

What is this often confused with?

Back 657

A characteristic peak between 2850 and 3100 cm^-1 from the presence of C-H bonds

The O-H peak in alcohols

Front 658

Why is the C-O peak for alcohols and esters not always reliable?

Back 658

Because it is in the fingerprint region

Front 659

List uses of infrared spectroscopy?

Back 659

1. Identification of pollutants

2. Breathalysers

Front 660

Describe identification of pollutants and infrared spectroscopy?

Back 660

1. Pollutants can be identified

2. Remote sensors analyse the IR spectra of vehicle emissions to detect and measure carbon monoxide, carbon dioxide and hydrocarbons in busy town centres or by motorways to monitor localised pollution

Front 661

Describe breathalysers infrared spectroscopy?

Back 661

1. Pass a beam of IR radiation through the captured breath in the sample chamber

2. Detects the IR absorbance of the compounds in the breath

3. Characteristic bonds present in ethanol are detected

4. The more IR absorbed, the higher the reading and the more ethanol in the breath

Front 662

What isthe typical sequence of the identifcation of an organic molecule? ANALYSIS TECHNIQUES AS

Back 662

1. Elemental analysis - percentage composition data o determine the empirical formula

2. Mass spectrometry - use of the molecular ion peak from a mass spectrum to determine molecular mass

3. Infrared spectroscopy - identify bonds and functional groups present

Front 663

Give reasons why CF2Cl2 was used as an aerosol propellant?

Back 663

1. Volatile

2. Non-toxic

3. Non-flammable

4. Easilyvaporised

5. Low reactivity

6. Does not hydrolyse in water

Front 664

When C12H26 is crcked a variety of alkanes and alkenes are formed with different chain lengths, explain why these are formed?

Back 664

Because the carbon–carbon bonds can break anywhere

Front 665

Give two reasons why the second ionisation energy of silicon is lower that the second ionisation energy of aluminium?

Back 665

1. The electron in Si is removed from a 3p orbital but in Al it is from a 3s orbital, which is at a lower energy level

2. The electron in silicon is more shielded

Front 666

Predict the element in Period 3 that has the highest second ionisation energy and why?

Back 666

Sodium because the second electron is removed from the second shell so the electron from the shell is nearer the nucelus so experiances greater nuclear attraction

Front 667

Explain why the ionsiation energy of every element is endothermic?

Back 667

Heat or energy needed to overcome the attraction between the negative electron and the positive protons

Front 668

State the general trend in the first ionsiation energies from carbon to neon. Deduce the element that deviates from this trend and explain why it does so?

Back 668

They increase from crabon to neon
Oxygen
Because the paired electrons in a 2p orbital repel

Front 669

Draw the graph of the trend in boiling and melting points across group 2?

Back 669

Front 670

Identify the element that deviates from the general trend of increasing ionisation energies across period 2 from elements lithium to nitrogen?

Back 670

Boron as an electron is removed from 2p orbital which is higher in energy so is more easily lost as it is more shielded and further from nucleus

Front 671

In a reaction NO2 and O2 are formed as gaseous products, describe why it is difficult to obtain a pure sample of nitrogen dioxide from this reactioN?

Back 671

Because there is a mixture of gasses and this is difficult to seperate

Front 672

Whose work lead to the formation of the current periodic table?

Back 672

The work of John Newlands and Dmitri Mendeleev

Front 673

Whos work was put forward in 1864?

Back 673

John Newlands

Front 674

What did John Newlands publish?

Back 674

Law of Octaves

Front 675

How did John Newlands arrnage elements according to the Law of Octaves?

Back 675

1. He arranged all elements known into a table in order of relative atomic mass.
2. He found a pattern among the early elements. The pattern showed that each element was similar to the element eight places ahead of it
3. He then put the similar elements into vertical columns, known as groups.

Front 676

What did Newlands Periodic table show?

Back 676

Newlands' table showed a repeating or periodic pattern of properties,

Front 677

Describe why Newlands work was not accepted by other scienetists?

Back 677

By ordering strictly according to atomic mass, Newlands was forced to put some elements into groups which did not match their chemical properties.

Front 678

Describe one of the mistakes Newlands made in his perioidc table?

Back 678

For example, he put iron (Fe), which is a metal, in the same group as oxygen (0) and sulfur (S), which are two non–metals.

Front 679

Who published a perioidc table in 1869?

Back 679

Dmitri Mendeleev published a periodic table.

Front 680

How did Mendeleev order his periodic table?

Back 680

Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he did some other things that made his table much more successful.

Front 681

Describe how Mendeleev's periodic table differed to Newlands?

Back 681

He realised that the physical and chemical properties of elements were related to their atomic mass in a 'periodic' way, and arranged them so that groups of elements with similar properties fell into vertical columns in his table.

Front 682

Describe why there where gaps in Mendeleev'speriodic table?

Back 682

Sometimes this method of arranging elements meant there were gaps in his horizontal rows or 'periods'. But instead of seeing this as a problem, Mendeleev thought it simply meant that the elements which belonged in the gaps had not yet been discovered.

Front 683

What did Mendeleev also predict?

Back 683

He was also able to work out the atomic mass of the missing elements, and so predict their properties. And when they were discovered, Mendeleev turned out to be right.

Front 684

Was it Newlands or Mendeleev's table that ordered elements by atomic weight?

Back 684

Both

Front 685

Was it Newlands or Mendeleev's table that Included only the elements known at the time?

Back 685

Newlands

Front 686

Was it Newlands or Mendeleev's table that left gaps for elements he predicted would be discovered later?

Back 686

Mendeleev

Front 687

Was it Newlands or Mendeleev's table that maintained a strict order of atomic weights ?

Back 687

Newlands

Front 688

Was it Newlands or Mendeleev's table that every eighth element had similar properties ?

Back 688

Newlands

Front 689

Was it Newlands or Mendeleev's table that was criticised by other scientists for grouping some elements with others when they were obviously very different to each other?

Back 689

Newlands

Front 690

Was it Newlands or Mendeleev's table that swapped the order of some elements if that fitted their properties better ?

Back 690

Mendeleev

Front 691

Was it Newlands or Mendeleev's table that elements in groups had similar properties?

Back 691

Mendeleev

Front 692

Was it Newlands or Mendeleev's table that was seen as a curiosity to begin with, but then as a useful tool when the predicted elements were discovered later ?

Back 692

Mendeleev

Front 693

Summarize Newlands Periodic Table? (5 Points)

Back 693

1. Elements ordered by atomic weight
2. Included only known elements
3. Had strict order of atomic weights
4. Every eighth element had a similar property
5. Was criticised by other scientists

Front 694

Summarize Mendeleev's Periodic Table? (5 Points)

Back 694

1. Elements ordered by atomic weight
2. Left gaps for predicted elements
3. Swapped order of elements according to their properties
4. Elements in groups had similar properties
5. Curiosity at first, yet proven accurate when predicted elements where discovered

Front 695

Describe the problem with Mendeleev's periodic table?

Back 695

Iodine has a lower relative atomic mass than tellurium, so it should come before tellurium in Mendeleev's table. In order to get iodine in the same group as other elements with similar properties – such as fluorine, chlorine and bromine – he had to put it after tellurium, which broke his own rules.

Front 696

What refined Mendeleev's table into the modern periodic table?

Back 696

The discovery of protons, neutrons and electrons in the early 20th century allowed Mendeleev’s table to be refined into the modern periodic table.

Front 697

How did the discovery of sub atomic particles help order the elements?

Back 697

It involved an important modification – the use of atomic number to order the elements. An element’s atomic number (also called proton number) is the number of protons in its atoms. So elements were ordered y their atomic number rather than mass

Front 698

Who used atomic number instead of atomic mass to order the modern periodic table?

Back 698

The British chemist Henry Moseley in 1913.

Front 699

How many elements are there in the periodic table?


How many horizontal rows are there in a periodic table?


How mnay vertical groups are there?

Back 699

114


7


18

Front 700

What does the number of the period of an electron give?

Back 700

The number of the period gives the number of the highest energy electron shell in an elements atoms

Front 701

Name some periodicity patterns evident in the periodic table?

Back 701

1. Electron configuratiuon
2. Ionisation energy
3. Structure
4. Melting points

Front 702

What is the trend for the beginning of each period?

Back 702

Each period starts with an electron in a new highest energy shell

Front 703

Describe the trend of filling a new highest energy shell across period 4?

Back 703

Although the 3d sub–shell is involved the highest sub shell number is n=4. From the n=4 shell only the 4s and 4p sub shells are occupied

Front 704

What is the trend down a group in the periodic table?

Back 704

1. Elements in the same group have the same number of electrons in their outer shell
2. Elements in each group also have atoms with the same number of electrons in each sub shell.


This gives electrons in the same group similar chemical properties

Front 705

State which two elements from the first twenty elements of the modern periodic table are not arranged in order of increasing atomic mass?

Back 705

Potassium and Argon

Front 706

Define ionisation energy?

Back 706

Ionisation energy is a measure of how easily an atom loses on electron to form positive ions

Front 707

Define the first ionisation energy?

Back 707

It is the energy required to remove one electron from each astom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions

Front 708

What is the first ionisation energy of sodium? Include state symbols?

Back 708

Na(g) –––> Na^+(g) + e^–

Front 709

What are the three factors that affect the ionisation energy of an atom?

Back 709

1. Atomic radius
2. Nuclear Charge
3. Electron shielding

Front 710

Describe the attraction the first electron lost experiances and how this effects ionisation energy?

Back 710

It experiances the least attraction from the nucelus as it is in the highest ionisation energy level so will be more easily lost

Front 711

Describe how atomic radius effects ionisation energy?

Back 711

The greater the distance betwwen the nucleus and the outer electron, the less the nucelar attraction.


The force of attraction falls off sharply with increasing distance, so atomic radius has a large effect

Front 712

Describe the effect of nuclear charge on ionisation energies?

Back 712

The more protons there are in the nucelus of an atom, the greater the attraction between the nucelus and the outer electrons

Front 713

Describe the effect of electron shileding on ionisation energies?

Back 713

Electrons are negatively charged and so the inner shell electrons repel the outer shell electrons. This repulsion, called the shielding effect, reduces the attraction between the nucelus and the outer electrons

Front 714

What is an ionised gas called?

Back 714

A plasma

Front 715

What is the equation for the second ionisation energy of helium?

Back 715

He^+(g) ––> He^2+(g) + e^–

Front 716

What is the difference between the first and second ionisation energies of helium, why?

Back 716

1. The second ionisation energy of helium is greater than the first.

2. This is because in a helium atom there are two protons attracting two electrons in the 1s subshell.

3. After the first electron is lost, the single electron is pulled closer to the helium nucleus.

4. The nuclear attraction on the remaining electron increases and more ionisation energy will be needed to remove this second electron

Front 717

Define the second ionisation energy?

Back 717

It is the energy required to remove one electron from each atom in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions

Front 718

What do successive ionisation energies provide the evidence for?

Back 718

The different electron energy levelsin an atom

Front 719

Give the graph for 8 successive ionisation energies of chlorine and explain why they are this?

Back 719

There is a large increase between the 7th and 8th electron because the electron is removed from a different shell, closer to the nucelus and with less shielding, so experiences greater nuclear attraction

Front 720

What do successive ionisation energies allow predictions to be made about?

Back 720

1. The number of electrons in the outer shell
2. The group of the element in the periodic table
3. The identity of an element

Front 721

What are the general trends in first ionisation energy across the periodic table for the first twenty elements?

Back 721

1. A general increase in ionisation energies across each period
2. There is a sharp decrease in first ionisation energy between the end of one period and the start of the next

Front 722

Draw a graph of the first ionisation energys of the first twenty element (hydrogen to calcium)?

Back 722

Front 723

Describe the trends shown in this graph?

Back 723

1. A general increase in ionisation energies across each period

2. There is a sharp decrease in first ionisation energy between the end of one period and the start of the next

Front 724

What are the elements that differ from the trend of increased ionisation energy across period 2?

Back 724

Boron and Oxygen

Front 725

What are the elements that differ from the trend of increased ionisation energy across period 3?

Back 725

Aluminium and sulfur

Front 726

Why does the ionisation energy down a group decrease?

Back 726

1. The atomic radius increases as it has more electrons
2. More inner shells so shielding increases
3. The Nuclear attraction on the outer electrons decreases
4. Therefore the first ionisation energy decreases

Front 727

Why does the first ionisation energy across a period increase?

Back 727

1. Nuclear charge increases
2. Same shell number, so similar shielding
3. Nuclear attraction increases
4. Atomic radius decreases
5. Therefore the first ionisation energy increases

Front 728

Why is the first ionisatation energy of boron lower than the first ionisation energy of beryllium?

Back 728

1. The 20 subshell in boron has a higher energy level than the 2s sub shell in beryllium
2. In boron, the 2p electron is easier to remove than the 2s electrons in beryllium
3. Therefore, the first ionisation energy of boron is less than the first ionisation energy of beryllium

Front 729

What does the fall in ionisation energy from beryllium to boron mark?

Back 729

The start of the filling of the 2p sub–shell

Front 730

What does the fall in first ionisation energy from nitrogen to oxygen mark?

Back 730

The start of electron pairing in the p–orbitals of the 2p sub shell

Front 731

Describe why there is a fall in first ionisation energy between nitorgen and oxygen?

Back 731

1. In nitrogen and oxygen, the highest energy electrons are in a 2p sub shell
2. In oxygen, the paired electrons in one of the 2p orbitals repel one another, making it easier to remove an electron from an oxygen than from a nitrogen atom
3. Therefore, the first ionisation energy of oxygen is less than the first ionisation energy of nitrogen

Front 732

What angles are the spins at of electrons in a p sub shell where there are only 3 electrons?

Back 732

They spin at right angles, equal repulsion as far apart as possible

Front 733

What can boron, silicon, germanium and arsenic also be called?

Back 733

Metalloids or semi–metals

Front 734

What are semi–metals also called?

Back 734

Metalloids

Front 735

What are metalloids also called?

Back 735

Semi–metals

Front 736

What are metalloids?

Back 736

They are the elements near to the metal/non–metal divide

Front 737

What is the trend in metal/non metal going down the group?


Where is this divide clearest?

Back 737

They do from non–metal to metal


In group 4/14, where carbon goes to lead

Front 738

Describe the ratio of non metallic elements to metallic elements?

Back 738

There are far more metallic elements than non–metallic elements

Front 739

At room temperature, all metals are solids. What is the exception to this statement?

Back 739

Mercury

Front 740

Describe the range of properties of the known metals?

Back 740

Some are strong and hard
Some are soft
Some are light
Some are very heavy

Front 741

Give one very hard and strong metal?

Back 741

Tungsten


Symbol: W

Front 742

Give one very soft metal?

Back 742

Lead


Symbol: Pb

Front 743

Give two very light metals?

Back 743

1. Aluminium

2. Lithium

Front 744

Give one very heavy metal?

Back 744

Osmium


Symbol: Os

Front 745

What is the one constant property of all metals?


What must be possible for this to happen?

Back 745

Their ability to conduct electricity.


This is a remarkable property for a solid as a charge must be able to move within a rigid structure for conduction to take place.

Front 746

Describe the features of metallic bonding?

Back 746

1. Each atom has donated its negative outer shell electrons, which are delocalised throughtout the whole structure
2. The positive ions (cations) left behind consist of the nucelus and the inner electron shells of the metal atoms

Front 747

What does delocalised mean?

Back 747

Spread out

Front 748

Define metallic bonding?

Back 748

It is the strong electrostation attraction between cations and delocalised electrons

Front 749

Describe the cations in a metal, and their influcence on its structure?

Back 749

The cations are fixed in position, maintaining the sturcture and shape of the metal

Front 750

Describe the delocalised electrons in a metal?

Back 750

They are mobile and are able to move throughout the structure

Front 751

What holds together atoms of a metal in a metal structure, what os this called?

Back 751

By metallic bonding in a giant metallic lattice

Front 752

What are the three common properties of metals?

Back 752

1. Strong metallic bonds
2. High electrical conductivity
3. High melting and boiling points

Front 753

What states do metals conduct electricity in?

Back 753

In both solid and liquid states

Front 754

What happens when a voltage is applied across a metal?

Back 754

The delocailised electrons can move through the sturcture, carrying the charge

Front 755

Describe the typical melting and boiling points of most metals?

Back 755

They have high melting and boiling points

Front 756

Which metal has the highest melting and boiling point?


What does this mean it is used for and why?

Back 756

Tungsten, W


In the filaments of halogen lamps, as other metals would melt

Front 757

Which group contains many metals with low melting points?


What melting point are they all below?

Back 757

Group 1 – the alkaline metals


They all have melting points below 200 degrees

Front 758

What does the melting point of a metal depend upon?

Back 758

The strength of the metallic bonding holdingtogether the atoms in the giant metallic lattice

Front 759

Explain why most metals have a high melting and boiling points?

Back 759

High temperatures are necessary to provide the large amount of energy needed to overcome the strong electrostatic attraction between the cations and electrons. This strong attarction results in most metals having high melting and boiling points

Front 760

Describe the solubility of metals?


Describe why this is surprising?


What would actually happen?

Back 760

Metals do not dissolve


Because it is expected that there would be interactions between the polar solvents and the charges within the ionic compounds


These interactions would lead to a reaction

Front 761

What happens to simple covalently bonded molecules when they form solids?


What does this mean?

Back 761

They form a simple molecular lattice strutcure held together by weak intermolecular forces


They have low melting and boiling points

Front 762

Name three elements that form a giant covalent lattice?

Back 762

Boron, carbon and silicon

Front 763

Describe the difference between the bonding in carbon, silicon and boron and simple molecules?

Back 763

I carbon, silicon and boron many billions of atoms are held together by a network of strong covalent bonds to form a giant covalent lattice

Front 764

Describe the bonding of diamond and silicon?

Back 764

They are both in group 14 (4) of the periodic table and so use these four electrons to form covalent bonds to other carbon of silicon atoms. The result is a tetrahedral sturcture with bond angles of 109.5 degrees

Front 765

What features of giant covalent lattices gives them many of their properties?

Back 765

The strong covalent bonds which make for very stable structures which are very diffciult to break down

Front 766

Describe the melting and boiling points of giant covalent lattices?

Back 766

They have high melting and boiling points because covalent bonds are strong. Therefore high temperatures are necessary to porvide the large quanitity of energy needed to break them.

Front 767

Describe the solunility of giant covalent lattices?

Back 767

The are insoluble in almost all solvents. This is because the covalent bonds holding together tha toms in the lattice are far too strong to be broken by interaction with solvents.

Front 768

What are the two exceptions to the general rule that all giant covalent structures are non–conductors of electricity?

Back 768

Graphene and graphite do conduct electricity and are both forms of carbon

Front 769

Why do carbon (diamond) and silicon not conduct electricity?

Back 769

Bevaise all four outer shell electrons are involved in covalent bonding, so none are free as mobile charge carriers to conduct electricity

Front 770

Apart from in carbon, what structures does carbon form?

Back 770

Giant covalent structures based on planar hexagonal layers

Front 771

Why are structures of carbon containing planar hexagonal layers good electrical coductors?

Back 771

Because only three electrons of the four outer shell electrons are used in covalent bonding. The reamining electron is released into a pool of delocalised electrons shared by all of the atos in the structure. These are free mobile charge carriers that can move through the structure and so conduct electricity

Front 772

What is Graphene?

Back 772

It is a single layer of graphite, composed of hexagonally arranged carbon atoms linked by strong covalent bonds.

Front 773

Describe Graphenes properties in comparision to others and what is unique about it?

Back 773

It has the same electrical conductivity as copper and is the thinnest and strongest material ever made

Front 774

Describe the structure of graphite?


Why can graphite conduct electricity?

Back 774

It is composed of parallel layers of hexagonally arranged carbon atomsthat are bonded together by weak London forces


Because only three of its outer shell electrons are involved in bonding. The spare electrons can act as mobile charge carriers to conduct electricity

Front 775

What is the trend in melting and boiling points across period 2 and 3?

Back 775

The melting point increases from Group 1 to group 14 (4). There is a sharp decrease in melting point between group 14 (4) and group 15 (5) and get lower to group 18 (0)

Front 776

Draw a graph for the trend in boiling points across group 2?

Back 776

Front 777

Draw a graph for the trend in boiling points across group 3?

Back 777

Front 778

Describe the trends in boiling point across group 2 shown by this graph?

Back 778

1. Initially giant metallic structures and giant covalent structures have high melting and boiling points as they have strong forces to overcome and therefore from group 1 to 4 the melting and boiling points increase2. There is a sharp decrease in melting and boiling points as from from group 4 to 5 the structure changes from giant to simple molecular structures

Front 779

Describe the trends in boiling point across group 3 shown by this graph?

Back 779

1. Initially giant metallic structures and giant covalent structures have high melting and boiling points as they have strong forces to overcome and therefore from group 1 to 4 the melting and boiling points increase

2. There is a sharp decrease in melting and boiling points as from from group 4 to 5 the structure changes from giant to simple molecular structures

Front 780

What is the symbol used to represent enthaply?

Back 780

H

Front 781

Define enthalpy?

Back 781

It is the heat content that is stored in a chemical system

Front 782

Define enthalpy change?

Back 782

The difference between the enthalpy of the products and the enthalpy of the reactants

Front 783

What is an enthalpy cycle?

Back 783

A diagram showing alternative routes between reactants and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess's law

Front 784

efine an enthalpy profile diagram?

Back 784

A diagram for a reaction to compare the enthalpy of the reactants with the enthalpy of the products

Front 785

What does the term chemical system mean?

Back 785

It refers to the atoms, molecules or ions making up the chemicals

Front 786

Define the term system?

Back 786

The chemicals involved in the reaction

Front 787

Define the term surroundings?

Back 787

Everything that is not the chemical system

Front 788

Define the term standard conditions?

Back 788

A pressure of 100kPa, a stated temperature, usually 298K (25 degrees) and a concentration of 1 mol dm^–3 (aqueous solutions)

Front 789

What is the standard condition only used when the reaction takes place with aquesous solutions?

Back 789

1 mol dm^–3 concentration

Front 790

Define the standard enthalpy change of combustion?

Back 790

The enthalpy change that takes place when one mole of substance reacts completely with oxygen under standard conditions, all reactants and products being in their standard states

Front 791

Define the dtanrad enthalpy change of formation?

Back 791

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states and under standard conditions

Front 792

What is the standard enthalpy change of neutralisation?

Back 792

It is the enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O under standard conditions, with all reactants and products in their standard states

Front 793

What is the standard enthalpy change of reaction?

Back 793

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standrad states

Front 794

What is enthalpy sometimes though of as?


Describe measuring enthalpy?

Back 794

It is the energy stored in bonds


It cannot be measured, but enthalpy changes can

Front 795

Describe the enthalpy of reactants and products in a reaction?

Back 795

They are likely to have different enthalpies

Front 796

What is the difference in enthalpies called?
What is the symbol for it?


How do you calculate it?

Back 796

The enthalpy changeΔH


ΔH = H(products) – H(reactants)

Front 797

Why can ΔH be positive or negative?

Back 797

Because it depends on whether the products contain more or less energy than the reactants

Front 798

What does the law of conservation of energy state?

Back 798

Energy cannot be created or destroyed

Front 799

When a chemical reaction takes place, what is the heat energy transferred between?

Back 799

The system and the surrondings

Front 800

Describe the universe in terms of enthalpy changes and chemical reactions?

Back 800

The universe is everything, and indluces both system and surrondings

Front 801

What are the directions of enthalpy transer?

Back 801

1. From the system to the surroundings – an exothermic change
2. From the surroundings to the system – an endothermic change

Front 802

Define an endothermic reaction?

Back 802

A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings, so ΔH is positive

Front 803

Define an exothermic reaction?

Back 803

A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surrondings, soΔH is neagtive

Front 804

Describe the direction of energy transfer in an exothermic reaction?

Back 804

1. Energy is transfered from the chemical system to the surrondings.
2. Any energy loss by the chemical system is balanced by the same energy gain by the surroundings
3. ΔH is negative
4. The temperature of the surroundings increases as they gain energy

Front 805

Describe the direction of energy transfer in an endothermic reaction? (More than 1 point)

Back 805

1. Energy is transfered from the surrondings to the chemical system2. Any energy loss by the surroundings is balanced by the same energy gain by the chemical systems
3. ΔH is positive
4. The temperature of the surroundings decreases as they lose energy

Front 806

What type of reaction is this?


What is the name of this type of diagram?

Back 806

Exothermic

It is an enthalpy profile diagram

Front 807

What type of reaction is this?

What is the name of this type of diagram?

Back 807

Endothermic

It is an enthalpy profile diagram

Front 808

Draw an enthalpy profile for an exothermic reaction without activation energy?

Back 808

Front 809

Draw an enthalpy profile diagram for an endothermic reaction without activation energy?

Back 809

Front 810

Describe bonds and reactions (the process)?

Back 810

1. Atoms and ions are held together by chemical bonds
2. During chemical reactions the bonds in the reactants need to be broken by an input of energy
3. New bonds in the products can then form to complete the reaction

Front 811

What is the energy input required to break bonds in a reaction called?


What does this act as to the reaction?

Back 811

The activation energy


It acts as an energy barrier to the reaction

Front 812

Define the activation energy?

Back 812

It is the minimum energy required to start a reaction by the breaking of bonds

Front 813

What is the symbol for activation energy?

Back 813

Front 814

What is activation energy in relation to a reaction?

Back 814

It is the minimum energy required for a reaction to take place

Front 815

Bond breaking is...


Why?

Back 815

Endothermic


Because energy is taken in by the system to break the bonds and meet the minimum activation energy

Front 816

Bond making is...

Back 816

Exothermic

Front 817

Draw a enthalpy change graph with the activation energy for the formation of magnesium oxide from its elements?

Back 817

Front 818

Draw a enthalpy change graph with the activation energy for an endothermic reaction?

Back 818

Front 819

What type of reaction does this enthalpy profile diagram show?

Back 819

Exothermic

Front 820

What type of reaction does this enthalpy profile diagram show?

Back 820

Endothermic

Front 821

Why do reactions with small activation energies take place very rapidally?

Back 821

Because the energy needed to break bondsis readily avalibale from the surrondings

Front 822

Describe the effect of very large activation energies?

Back 822

The reaction may take place extremelty slowly or not at all because lots of energy is needed to be taken in to break the bonds

Front 823

What can effect the enthalpy change for a reaction?

Back 823

The conditions used

Front 824

What is the symvol to represent standard conditions?

Back 824

Front 825

What does this formula mean/represent?

Back 825

The change in enthalpy under standard conditions, with x being the type of change

Front 826

Give the formula for the change in enthalpy under standard conditions, with x representing the type of change?

Back 826

Front 827

What are the units of enthalpy change?

Back 827

kJmol^–1

Front 828

What is the standard pressure used in standard conditions?

Back 828

100 kPa which is very close to the pressure of one atmosphere, 101kPa

Front 829

What is the standard temperature used in standard conditions?

Back 829

It is a stated temperature, usuaully 298 K (25 degrees celcius)

Front 830

What is the standard concentration used in standard conditions?

Back 830

This is relevant for solution only but is 1moldm^–1

Front 831

What is the standard state used in standard conditions?

Back 831

It is the physical state of a substance under standard conditions, most commonly being 100kPa and 298K

Front 832

Draw the symbol for the standard enthalphy change of combustion?

Back 832

Front 833

Draw the symbol for the standard enthalphy change of formation?

Back 833

Front 834

Draw the symbol for the standard enthalphy change of reaction?

Back 834

Front 835

Draw the symbol for the standard enthalphy change of neutralisation?

Back 835

There is a H here

Front 836

What is this the symbol for?

Back 836

The standard enthalpy change of combustion

Front 837

What is this the symbol for?

Back 837

The standard enthalpy change of formation

Front 838

What is this the symbol for?

Back 838

The standard enthalpy change of neutralisation

Front 839

What is this the symbol for?

Back 839

The standard enthalpy change of reaction

Front 840

What does this always refer to?


What does its value depend upon?


Therefore what should you do when doing this?

Back 840

To a stated equation

The balancing numbers

Work out the enthalpies for the balancing numbers shown in the equation

Front 841

What Should always be done with reactions from which the standard enthalpy change of formation is being worked out from?

Back 841

Because the defintion says 'one mole of a compound is formed', no balancing number should be added in front of the product that is formed, only in front of the reactants

Front 842

Descrinbe the enthalpy change for the formation of one mole of an element from its element under the standard enthalpy change of formation?

Back 842

This is no change, so all elements have a an enthalpy change of formation of 0 kJmol^–1

Front 843

When a substance reacts compleltey with oxygen, what are the products?

Back 843

The oxides of the elements in the substance

Front 844

Describe what must be taken into account during enthalpy change of combustion when balancing equations?

Back 844

Because the definition requires the reaction of one mole of substance the eqaution must be balanced with half numbers to make sure only one mole of the substance is present

Front 845

When you carry out experiments to determine enthalpy changes, what part of the universe is the thermometer?

Back 845

It is part of the surroundings and you are measuring the temperature change of the surrondings

Front 846

What is absolute zero?

Back 846

It is 0K and is equivilent to –273 degrees centigrade

Front 847

Where does ice melt on the kelvin scale?


Where does water boil on the kelvin scale?

Back 847

273 K (0 degrees)


373 K (100 degrees)

Front 848

What is a 1K rise in temperature equivalent to?

Therefore what must be taken into account when measuring energy changes in enthalpy reactions using degrees centigrade?

Back 848

1 degrees celcius


Nothing, the value of the temperature change is exactly the same in celsius as it is in kelvin

Front 849

What three quattities are used to calculate the energy change of the surrondings?

Back 849

Mass, specific heat capacity and temperature change

Front 850

How do you measure the mass of the surrondings to cacluate enthalpy change?

Back 850

By weighing in grams

Front 851

Define the specific heat capacity?


What is the symbol for it?

Back 851

The energy required to raise the temperature of 1g of substance by 1 degree celcius


c

Front 852

Describe the size of the specific heat capacity of a...


1. Metal
2. Insulator

Back 852

1. Has a small value
2. Has a large value

Front 853

How do you determine the temperature change of the surrondings?

Back 853

Using a thermometer, the change in temperature = T(final) – T(initial)

Front 854

What symbol gives the energy? Not energy change
What formula is used to calculate it?

Back 854

q
q=mcdeltaT

Front 855

How do you convert from celcius to Kelvin?

Back 855

Add 273 to celcius reading

Front 856

Describe the process of the reaction to determine the enthalpy change of combustion?

Back 856

1. Using a measuring cylinder, measure 150cm^3 of water. Pour the water into a beaker, record the initial temperature of the water
2. Add fuel to the spiritburner. Weight it.
3. Place it under the beaker, light it and burn the fuel whilst stirring the water with a thermometer
4. After three minutes, extinguish the flame, record the maximum temperature of the water
5. Re–weight the spirit burner, assuming the wick has not been burnt

Front 857

How you use your results from the experiment to determine the enthalpy change of combustion?

Back 857

1. Use q=mcdeltaT to calculate the energy change of the water and divide by 1000 to convert to kJ
2. Calculate the number of moles of substance burnt
3. Divide the energy transferred by the number of moles to get the energy of combustion

Front 858

What is the density of water?


What does this mean in q=mcdeltaT

Back 858

It is 1gcm^–3


The mass of the water is the same as its value in cm^3

Front 859

List possible reasons why the determination of an enthalpy change of a combustion experiment is not accurate?

Back 859

1. Heat loss to the surrondings other than the water, including the beaker and air
2. Incomplete combustion of fuel, CO would be produced instead of CO2, forming black soot
3. Evaporation of fuel from the wick
4. Non–standard conditions
5. Weighting errors

Front 860

Describe how not using stanard conditions will mean the value of enthalpy change of combustion will differ to the book value?

Back 860

Because the book vlaue is a standard value, the conditions have to be exactly the same for the same value to be obtained as the value can change depending on the conditions used

Front 861

Describe how evaporation of fuel from the wick would make the results obtained from the determination of an enthalpy change of combustion inaccurate?


Describe how to minimise this?

Back 861

If some fuel evaporates from the wick, it will show a greater change in mass than was actually present


The burner must be weighed as soon as possible after extinguishing the flame. Spirit burners usually have a cover to reduce this error.

Front 862

Why are group 2 elements called a reducing agent?

Back 862

Because each metal atom is oxidised, losing electrons. Another species will gain these two electrons and be reduced. The reducing agent has reduced another species

Front 863

Group 2 element + oxygen –––>

Back 863

Metal oxide

Front 864

Group 2 elememts + water –––>

Back 864

Alkaline hydroxide

Front 865

What is the general formula of group 2 oxides?

Back 865

MO

Front 866

What is the general formula of group 2 hydroxides?

Back 866

M(OH)2

Front 867

Metal + acid –––>

Back 867

Salt + hydrogen

Front 868

Describe the reactivity trends in group 2?

Back 868

The reactivity increases down group 2

Front 869

Why does the ionisation energy decrease down the group? (general)

Back 869

The attraction between the nucleus and the outer electrons decreases as a result of increasing atomic radius and increasing shielding

Front 870

Describe the trends in group 2 elements?

Back 870

They become more reactive and stronger reducing agents down the group

Front 871

When group 2 elements react, what is the main bulk of energy change due to?

Back 871

Ionisation energies

Front 872

What happens when the oxides of group 2 elements reacts with water?

Back 872

They release hydroxide ions, forming alkaline solutions of the metal hydroxide

Front 873

CaO + H2O –––>
Give the next stage of the reaction?

Back 873

Ca^2+ + 2OH^–
Ca^2+ + 2OH^– ––> Ca(OH)2

Front 874

In measuring enthalpy, name two ways that errors from heat loss and incomplete combustion could be recorded?

Back 874

1. Draught screens
2. Input of oxygen gas

Front 875

Why are polysterene cups used when determination of an enthalpy change?

Back 875

They are cheap, waterproof and light weight and offer some insulation against heat loss to the surrondings

Front 876

When carrying out reactions between aquesous solution, what is the immediate surrondings?

Back 876

The solution itself

Front 877

Describe energy transfer and reactions between aqueous solutions?

Back 877

The chemical particles within the solutions may react when they collide and any energy transfer is between the chemical particles and the water molecules on the solution

Front 878

How do you determine the heat of combustion in a reaction?

Back 878

1. Calculate the energy change (q) of the water in Kj
2. Calculate the number of moles of fuel burnt
3. Divide the energy change by the number of moles

Front 879

What are the units of an enthalpy change?

Back 879

kJmol^–1

Front 880

How do you determin the heat of formation?

Back 880

1. Calculate the energy change (q) in solution in kJ
2. Calculate the amount of the limiting reagent in excess
3. Divide the kJ of energy by the number of moles

Front 881

Define average bond enthalpy?

Back 881

It is the energy required to break one mole of a specified type of bond in a gaseous molecule

Front 882

What is required to break bonds?

Back 882

Energy

Front 883

Because energy is required to break bonds... what are bond enthalpies always?

Back 883

1. Endothermic
2. Have a positive value

Front 884

What can make the actual bond enthalpy vary?

Back 884

The chemical environment of the bond

Front 885

How do you calculate an average bond enthalpy?

Back 885

It is calculated from the actual bond enthalpies in different chemical environments

Front 886

Bond breaking is...

Back 886

...endothermic

Front 887

Bond making...

Back 887

...exothermic

Front 888

Energy is required to...

Back 888

...break bonds and is endothermic

Front 889

Energy is released when...

Back 889

...when bonds form bond making is exothermic

Front 890

What determine whether an overall reaction is exothermic or endothermic?

Back 890

The difference between the energy required for bond breaking and the energy released by bond making

Front 891

In exothermic reactions, describe the difference between bond breaking and bond making?

Back 891

The energy released when making bonds is greater than the energy required when breaking bonds

Front 892

In endothermic reactions, describe the difference between bond breaking and bond making?

Back 892

The energy reaquired when breaking bonds is greater than the energy released when making bonds

Front 893

What is the equation to calculate the enthalpy change of reaction from bond enthalpies of the bonds in the reactants and the products?

Back 893

Delta(r)H = E(Bond enthalpies in reactants) – E(bond enthalpies in products)

Front 894

What does the purple line represent?

Back 894

Bond breaking

Front 895

What does the yellow line mean?

Back 895

Bond making

Front 896

What does the purple line mean?

Back 896

Breaking bonds

Front 897

What does the yellow line mean?

Back 897

Making bonds

Front 898

What are the limitatuions of using bond enthalpies to caluclate the enthalpy change of a reaction?

Back 898

1. The actual energy involved would be slighly different as the bonds may be in different environments

Front 899

What is the requirement of calculations using the average bonbd enthalpies?


Therefore, what are you not calculating?

Back 899

They need all species to be gaseous moles


The standard enthalpy change

Front 900

Give three reasons why you might not be able to determine the ethalpy change of a reaction?

Back 900

1. The reaction is too slow
2. The reaction is incomplete
3. Other reactions occur

Front 901

What does Hess law allow?

Back 901

Enthalpy changes to be determined indireclty

Front 902

What does Hess' law state?

Back 902

If a reaction can take place by two route, and the starting and finishing conditions are the same, the total enthalpy change is the same for each route

Front 903

What can intermediates be? Hesses law, enthalpy cycle diagrams.

Back 903

1. Elements if (delta)HF is known
2. Oxides if (delta)Hc is known
3. Gaseous atoms if E[X–Y] is known

Front 904

What is the equation for the enthalpy change of formation?

Back 904

Delta(r)H = E(delta)fH products – E(delta)fH reactants

Front 905

What is the equation for the enthalpy change of combustion?

Back 905

Delta(r)H = E(delta)cH reactants – E(delta)cH products

Front 906

Describe the direction of the arrow when the intermediate is elements?

Back 906

The arrows go up from the elements to the products/reactants

Front 907

Describe the direction of the arrow when the intermediate is oxides?

Back 907

They go down from the reactants/products to the combustion products

Front 908

Why are there two stages in the reaction of group 2 oxides with water?

Back 908

The group 2 hydroxides are only slightly soluble inwater. When a solution becomes saturated, any further metal and hydroxide ions will form a sold precipitate

Front 909

Describe the trend in the solubility of group two hydroxides?

Back 909

The solubility of the hydroxides in water increased down the group

Front 910

Describe the properties of the solutions containing the more soluble hydroxides?

Back 910

The resulting solutions containing the more soluble hydroxides of group 2 contain more OH^– ions and therefore are more alkaline

Front 911

Draw an arrow indicating the direction of increased solubility?

Back 911

Front 912

Draw an arrow indicating the direction of increased pH?

Back 912

They become more alkaline down the group

Front 913

Draw an arrow indicating the direction of increased alkalinity?

Back 913

The pH increases down the group

Front 914

Describe the differences between Magnesium hydroxide and Barium hydroxide?

Back 914

Mg(OH)2 is only very slightly soluble in water. The solution has a low OH^–(aq) concentration and a pH of around 10Ba(OH)2 is more soluble in water. The solution has a greater OH^–(aq) concentration and a pH or around 13

Front 915

Describe the method of the experment to prove that the solubility of the group 2 hydroxides increases down the group?

Back 915

1. Add a spatula of each group 2 oxide to water in a test tube
2. Shake the mixture. On this scale, there is insufficient water to dissolve all of the metal hydroxide that forms. You will have a saturated solution of each metal hydroxide with some white solid undissolved at the bottom
3. Measure the pH of each solution. The alkalinity will be seen to increase down the group

Front 916

Why do group 2 oxides, hydroxides and carbonates have many uses?

Back 916

Due to their basic properties and ability to neutralise acids

Front 917

Describe the uses of calcium hydroxide?

Back 917

It is added to fields as lime by farmers to increase the pH of the acidic soils. The calcium hydroxide neutralises the soil, forming neutral water

Front 918

Give the reaction through which calcium hydroxide neutralises water in agriculture?

Back 918

Ca(OH)2 + 2H^+ ––> Ca^2+ + 2H2O

Front 919

Give one group 2 hydroxide used in agriculture?

Back 919

Calcium hydroxide, lime

Front 920

How are group 2 bases often used in medicine?

Back 920

As antaacids for treating acid indigestion

Front 921

What do many indegestion tablets use?


Why?

Back 921

Magnesium and calcium carbonates


Their alkalinity is used to neutralise acid

Front 922

Describe milk of magneisa?

Back 922

It is a suspension of white magnesium hydroxide – Mg(OH)2 – in water. It is only very slightly soluble in water. It is used to neutralise stomach acid (HCl)

Front 923

Give the neutralisation of stomach acid by magnesium hydroxide?

Back 923

Mg(OH)2 + 2HCl ––> MgCl2 + 2H2O

Front 924

Give the neutralisation of stomach acid by calcium carbonate?

Back 924

CaCO3 + 2HCl ––> CaCl2 + 2H2O + CO2

Front 925

Explain why group two elements are reducing agents?

Back 925

Group 2 metals add electrons to other specieis

Front 926

Explain why group two elements become more reactive down the group?

Back 926

Down group 2, the total energy from first and second ionisation energies decreases as the nucelar attraction on the outer electron decreases because of increased atomic radius and increased shielding. It therefore becomes easeir to renove the electrons and the reactivity increases

Front 927

Describe the reactivity of the halogens?

Back 927

They are the most reactive non–metallic group

Front 928

Why do halogens not occur in their elemental form in nature?

Back 928

Because they are very reactive and so form compounds

Front 929

On earth, how do halogens occur?

Back 929

As stable halide ions dissolved in sea water or combined with sodium or potassium as solid deposits such as in salt mines containing the common salt, NaCl

Front 930

What do the halogens exist at at Room temperature and pressure? In terms of chemical structure, not state

Back 930

Diatomic molecules – X2

Front 931

Describe the states of halogens at room temperature?

Back 931

The change from a gas to a liquid to a solid down the group

Front 932

Describe the sturctures of halogens in their solid states?

Back 932

They form lattices with simple molecular structures

Front 933

Draw an arrow to show the trend in boiling point in the halogens?

Back 933

Front 934

Explain me!

Back 934

1. More electrons
2. Stronger London forces
3. More energy required to break the intermolecular forces
4. Boiling point increases

Front 935

Describe the appearance and state of fluroine at RTP?

Back 935

Pale yellow gas

Front 936

Describe the appearance and state of chlorine at RTP?

Back 936

Pale green gas

Front 937

Describe the appearance and state of bromine at RTP?

Back 937

Red–brown liquid

Front 938

Describe the appearance and state of iodine at RTP?

Back 938

Shiny grey–black solid

Front 939

Describe the appearance and state of astatine at RTP?

Back 939

Never been seen

Front 940

Describe the electronic configuration of a halogen?

Back 940

They have seven outer shell electrons, just one electron short of the electronic configuration of a nobel gas. Two electrons are in the outer s sub–shell and five in the outer p sub shell

Front 941

What is the most common type of reaction of the halogens?

Back 941

Redox reactions

Front 942

Describe what happens to halogens in redox reactions?

Back 942

Each halogen atom is reduced, gaining one electron to form a 1 negative halide ion with the electron configuration of the nerest nobel gas

Front 943

Draw the half equation for the oxidation of chlorine?

Back 943

Cl2 + 2e^– ––> 2 Cl^–

Front 944

Why are the halogens called oxidisng agents?

Back 944

Because another specieis loses electrons to halogen atoms, therefore being oxidised. The halogen is called an oxidisng agent because it has oxidised another species

Front 945

DEscribe the tred in reactivity of the halogens?

Back 945

It decreases down the group

Front 946

Describe how to porve that the reactibvity of the halogens decreasesdown the group?

Back 946

1. Add a solution of each halogen to aqueous solutions of the other halides
2. If the halogen is more reactive than the halide present a reaction takes place, the halogen displacing the halide from the solution
3. The solution changes colour

Front 947

Describe what happens if a more reactive halogen reacts with another halogen in aqueous solution?

Back 947

1. A reaction takes place, the halogen displacing the halide from the solution
2. The solution changes colour

Front 948

DEscribe the colour of iodie and bromine in water in terms of colour?

Back 948

They can appear a similar orange–brown colour depending on the concentration

Front 949

Solutions of iodine and bromine can appear a similar orange–brown colour depending on the concentration, how do we tell them apart?

Back 949

1. An organic non–oplar solvent such as cyclohexane is added and the mixture shaken
2. The non–polar halogens dissolve more readily in cyclohexane than water
3. In cyclohexane their colours are much easier to tell apart

Front 950

Describe the colour of chlorine in water?

Back 950

Plae green

Front 951

Describe the colour of bromine in water?

Back 951

Organe

Front 952

Describe the colour of iodine in solution?

Back 952

Brown

Front 953

Describe the colour of chlorine in cyclohexane?

Back 953

Pale green

Front 954

Describe the colour of bromine in cyclohexane?

Back 954

Orange

Front 955

Describe the colour of iodine in cyclohexane?

Back 955

Violet

Front 956

Describe the colour change when chlroine is added to aquesous solutions of...


1. Bromine
2. Iodine

Back 956

1. Orange colour from Br2 formation
2. Violet colour from iodine formation

Front 957

Describe the colour change when bromine is added to aqueous solutions of...


1. Chlorine
2. Iodine

Back 957

1. No reaction
2. Violet colour from I2 formation

Front 958

Describe the colour change when iodine is added to aqueous solutions of...

1. Chlorine
2. Bromine

Back 958

1. No reaction
2. No reaction

Front 959

What two halogens does chlorine react with when reacted with bromine and iodine?

Back 959

Chrloine reacts with both Br^– and I^–

Front 960

What halogens does bromine displace with when reacted with chlorine and iodine?

Back 960

Bromine has reacted with I^– only

Front 961

What two halogens does iodine react with when reacted with chlorine and bromine?

Back 961

Iodine has not reacted at all

Front 962

What halogen does this show?

Back 962

Chlorine in water

Front 963

What halogen does this show?

Back 963

Iodine in water

Front 964

What halogen does this show?

Back 964

Iodine in cyclohexane

Front 965

What halogen does this show?

Back 965

Iodine in water

Front 966

What halogen does this show?

Back 966

Chlorine in cyclohexane

Front 967

What halogen does this show?

Back 967

Bromine in cyclohexane

Front 968

Decribe the colour of fluroine and its reacivity?

Back 968

Fluroine is a plae yellow gas, reacting with almost any substance that it comes in contact with

Front 969

Describe why astatine is extremely rare?


Describe the prediction about it?

Back 969

Because it is radioactive and decays rapidally so the element has never actually been seen


It is predicted to be the least reactive halogen

Front 970

Describe the trend in tendancy to gain electrons in halogens down the group?

Back 970

Down the group, the tendency to gain an electron decreases an the halogens become less reactive

Front 971

Why do the halogens become less reactive down the group/

Back 971

1. Atomic radius increases
2. More inner shells so shielding increases
3. Less nuclear attraction to capture an electron from other species
4. Reactivity decreases

Front 972

Which of the halogens is the strongest oxidising agent?

Back 972

Fluroine, it gains electrons from other specieis more readily than other halogens

Front 973

Describe the trend in oxidising agents down the group of halogens?

Back 973

They become weaker oxidisng agents down the group

Front 974

Define disproportionation?

Back 974

It is a redox reaction in which the same element is both oxidised and reduced

Front 975

What is the name given to a reaction in which the same element is both oxidised and reduced?

Back 975

Disproportionation

Front 976

Give two exaple of disproportionation reactions?

Back 976

1. The reaction of chlorine with water
2. The reaction of chlorine with cold, dilute sodium hydroxide

Front 977

Give a use of chlorine?

Back 977

1. It is used in water purification
2. As a disinfectants
3. Reduces the incidence of waterborn diseases by killing harmful bacteria

Front 978

What happens when small amounts of chlroine is added to water?

Back 978

A disproportionation reaction takes place in which for each chlorine molecule, one chlorine atom is oxidised and the other is reduced (as they are diatomic)

Front 979

What are the products of the disproportionation reaction of chlroine with water?

Back 979

Two acids:
1. Chloric(I) acid, HClO
2. HCl

Front 980

Cl2 + H2O ––>

Back 980

HClO + HCl

Front 981

Describe what part of chrloine dissolved in water kill bacteria?

Back 981

1. Chloric(I) acid, HClO3
2. Chlorate (I) ions, ClO^–
Not the chrloine

Front 982

Describe the use of Chloric(I0 acid other than in water purification?

Back 982

As a weak bleach

Front 983

Describe how to show that chloric(I) acid acts as a weak bleach?

Back 983

Add some indicator solution to a solution of chlorine in water. First it turns red, form the presence of the two acids, the colour then disappears as the bleaching action of the chloric(I) acid takes effect

Front 984

Why is the reaction of chlorine with water limited?


How can you overcome this?

Back 984

Due to the low solubility of chlorine in water


By using water containing dissolved sodium hydroxide so much more chlorine dissolves and another disproportionation reaction takes place

Front 985

Cl2 + 2NaOH

Back 985

––> NaClO + NaCl + H2O

Front 986

Cl2 + 2NaOH ––> NaClO + NaCl + H2O

Describe why the product of this reaction is useful as a household bleach?

Back 986

The resulting solution contains a large concentration of chlorate(I) ClO^– ions from sodium chlorate, NaClO, that is formed

Front 987

Describe the conditions for this specific reaction:


Cl2 + 2NaOH ––> NaClO + NaCl + H2O

Back 987

Reacting chlorine with a cold dilute aqueous sodium hydroxide

Front 988

What is the benifit of adding chlorine to water?

Back 988

It makes our water fit to drink and kills bacteria

Front 989

Describe the dissadvantage of adding chlorine to our water?

Back 989

1. It is extremely toxic
2. It is a respiratory irritant in small concentrations
3. Large concentrations can be fatal

Front 990

What does decaying vegetation release?

Back 990

Methane amongst other organic hydrocarbons

Front 991

What happens whe chlorine in drinking water reacts with organic hydrocarbons such as methane fromed from decaying vegetation?

Back 991

Chlorinated hydrocarbons are formed, which are suspected of causing cancer

Front 992

Describe the balance of risks from adding chlorine to drinking water?

Back 992

The oberall risk to health of not adding chlorine to the water supply is far greater than the risk posed by the chlorinated hydrocarbons. The quality of drinking water would be compromised and diseases such as typoid and cholera might break out

Front 993

Give two diseases that may arise if chlorine is not added to drinking water?

Back 993

Typhoid and cholera

Front 994

After a natural disaster, what it one of the very first, life saving tasks?

Back 994

Ensuring that the survivors have a safe water supply

Front 995

What happens when aquesous halide ions react with aqueous silver ions?

Back 995

They form precipitates of silver halides

Front 996

Show the reaction between aqueous halide ions and aqueous silver ions where X^– is used to represent the halide ion?

Back 996

Ag^+(aq) + X^(aq) –––> AgX(s)

Front 997

What is quantitative analysis?

Back 997

A tachnique with numerical results

Front 998

What does qualitative analysis rely upon?


On what scale can they be carried out?


Give examples of observations?

Back 998

Simple observations rather than measurements


Quickly on a test tube scale


Gas bubbles, precipitates, colour changes, or identification of gases

Front 999

What happens when carbonates react with acids

Back 999

They form carbon dioxide gas

Front 1000

Give the equation for the reaction of nitric acid with sodium carbonate?

Back 1000

Na2CO3 + HNO3 ––> 2NaNO3 + CO2 + H2O

Front 1001

Describe the process to test for a carbonate ion?

Back 1001

1. Add dilute nitric acid to a solid or solution
2. If you see bubbles, the unknown compound could be a carbonate
3. To prove this, bubble the gas through lime water
4. Carbon dioxide reacts to form a fine white precipitate of calcium carbomate which turns the lime water cloudy

Front 1002

What is lime water?

Back 1002

A saturated aqueous solution of calcium hydroxide, Ca(OH)2

Front 1003

Give the equation for the reaction of carbon dioxide with lime water?

Back 1003

CO2 + Ca(OH)2 ––> CaCO3 + H2O

Front 1004

What is the change in limewater for the positive test of co2?

Back 1004

Front 1005

Is this test for Co2 positive or negative?

Back 1005

Positive

Front 1006

Describe the general solubility of sulfates in water?


Give one exception?

Back 1006

They are mostly soluble in water


Barium sulfate BaSO4 is very insoluble

Front 1007

Name on very insoluble sulfate?

Back 1007

BaSO4, barium sulfate

Front 1008

How do you carry out a test for sulfate ions?

Back 1008

1. Add aqeuous barium ions
2. A white precipitate of barium sulfate is formed if sulfate ions are present

Front 1009

What are insoluble salts and how are they made?

Back 1009

Insoluble salts do not dissolve in water. They can be made by mixing appropriate solutions of ions together.

Front 1010

What is a precipitation reaction?

Back 1010

A reaction in which an insoluble solid is formed

Front 1011

What can precipitation reactions be used for?

Back 1011

Precipitation reactions can be used to remove unwanted ions in solution. This is useful for treating drinking water and wastewater.

Front 1012

When writing half equations:
1. If the first thing is negative......
2. If the first thing is positive.......

Back 1012

1. The electrons go on the right side
2. The electrons go on the left side

Front 1013

Give five properties of alkali metals?

Back 1013

1. The alkali metals are soft
2. They are reactive metals.
3. They react vigorously with water to produce a hydroxide and hydrogen 4. They have a low density
5. Their hydroxides dissolve in water to form alkaline solutions

Front 1014

Describe the colours of an ionic compound?

Back 1014

The ionic compounds produced are white solids which form colourless solutions when they dissolve.

Front 1015

What happens when sodium brunsin oxygen?

Back 1015

A metal oxide is formed. sodium + oxygen → sodium oxide

Front 1016

Describe displacement reactions and halogens?

Back 1016

In these reactions, a more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.

Front 1017

Describe the product of chlorine + sodium bromide?

Back 1017

chlorine + sodium bromide → sodium chloride + bromine

Front 1018

Describe the displacement reactions in halogens using chlorine, sodium and bromide as the examples?

Back 1018

1. Bromine forms an ionic bond with sodium forming sodium bromide (salt)
2. Sodium bromide then dissolves in water
3. Chlorine when added then displaces the bromide

Front 1019

How can you work out the reactivity series for halogens?

Back 1019

If you test different combinations of the halogens and their salts you can work out a reactivity series for the halogens.

Front 1020

Describe the displacement of the most reactive salt and the least reactive halogen from solutions of their salt

Back 1020

The most reactive halogen displaces all the other halogens from solutions of their salts, while the least reactive halogen is always displaced.

Front 1021

How can ethanoic acid be obatined from ethanol

Back 1021

Ethanoic acid is formed from the mild oxidation of the ethanol

Front 1022

What two ways can ethanol be oxidised to form ethanoic acid?

Back 1022

1.The addition of chemical oxidising agents – such as acidified potassium dichromate.
2.The action of microbes in aerobic conditions. This happens on a small scale when a bottle of wine is left open and exposed to air. On a commercial scale, it is achieved in a fermenter using acetic acid bacteria.

Front 1023

Give the properties of carboxylic acids?

Back 1023

1.They dissolve in water to produce acidic solutions (pH less than 7).
2.They react with carbonates to produce carbon dioxide and a salt and water.
3.They all react with alcohols, in the presence of an acid catalyst, to form esters

Front 1024

What happens to strong acids in water?

Back 1024

Strong acid, such as hydrochloric acid, ionise fully in water.Their aqueous solutions have a high concentration of hydrogen ions, H+. This gives them a low pH.

Front 1025

What form of acids are carboxylic acids?

Back 1025

Carboxylic acids are weak acids

Front 1026

What happens when weak acids are placed in water

Back 1026

They do not completely ionise when they are dissolved in water. Instead only some of their molecules ionise to form H+ ions

Front 1027

Compare the pH of stong and weak acids dissolved in water?

Back 1027

This means that an aqueous solution of a weak acid will have a higher pH compared to the same concentration of an aqueous solution of a strong acid.

Front 1028

What are esters?

Back 1028

Esters are a group of organic compounds which all contain the functional group–COO–.

Front 1029

Give the two common properties of esters?

Back 1029

1. They are volatile – they are liquids that become vapours easily
2. They have distinctive ‘fruity’ smells

Front 1030

Describe what properties make esters useful, and what for? Also where are they obtained from?

Back 1030

These properties make esters very useful as food flavourings, and asperfumes in cosmetics. Some esters are obtained from natural sources, such as fruits. Others are manufactured.

Front 1031

How is Ethyl Ethanoate formed?

Back 1031

Ethyl ethanoate is the ester made from ethanol and ethanoic acid. Sulfuric acid is added to act as a catalyst in the reaction.

Front 1032

How can the smell of Ethyl Ethonate be detected?
How are excess substances neutralised?

Back 1032

The distinctive smell of ethyl ethanoate can be detected as the reaction proceeds. Excess ethanoic acid in the reaction mixture is neutralised with sodium hydrogen carbonate, then a few drops of the mixture is added to water so that the smell can be detected more effectively.

Front 1033

Give the formula for ethyl ethonate?

Back 1033

CH3CH2OOCCH3

Front 1034

Give the names of the esters formed from:
1. Ethanol and propanoic acid
2. Butanol and methanoic acid
3. Pentanol and ethanoic acid

Back 1034

1. Ethyl Ethonate
2. Butyl Methanoate
3. Pentyl Ethonate

Front 1035

What are flame tests used to detect?

Back 1035

Flame tests are used to detect the presence of a particular metal ion in acompound.

Front 1036

How can you use flames to detect different metal ions?

Back 1036

Metal ions change the colour of a flame when they are heated in it. Different metal ions give different colours to the flame – so flame tests can be used to identify the presence of a particular metal in a sample.

Front 1037

How do you carry out a typical flame test?

Back 1037

1.Dip a clean nichrome wire in the sample solution
2. Hold the nichrome wire at the edge of a Bunsen burner flame
3. Observe the changed colour of the flame, and decide which metal it indicates
4. Clean the wire in acid and rinse with water, then repeat steps 1 to 3 with a new sample

Front 1038

What flame colour does a lithium ion give?

Back 1038

Crimson

Front 1039

Which ion does the colour Crimson indicate is present?

Back 1039

Lithium

Front 1040

What flame colour does a sodium ion give?

Back 1040

Yellow

Front 1041

Which ion does the colour yellow indicate is present?

Back 1041

sodium

Front 1042

What flame colour does a potassium ion give?

Back 1042

Lillac

Front 1043

What ion does the colour lillac indicate is present in a flame test?

Back 1043

Potassium ion

Front 1044

What flame colour does calcium give?

Back 1044

Red

Front 1045

What ion does a red flame indicate is present?

Back 1045

Calcium

Front 1046

What colour does a barium ion give off in a flame test?

Back 1046

Green

Front 1047

What ion does a green flame show?

Back 1047

Barium

Front 1048

What do some reactions form? How do they appear?

Back 1048

Some reactions form a precipitate – this is an insoluble solid formed in the reaction. Precipitates often appear as small particles suspended in a solution.

Front 1049

When may a precipitate be formed?

Back 1049

A precipitate may be formed when a few drops of sodium hydroxide are added to a solution of a metal compound.

Front 1050

What happens when sodium hydroxide is added to Copper [II] sulfate?

Back 1050

copper(II) sulfate + sodium hydroxide → copper hydroxide + sodium sulfate

Front 1051

What coloured precipitate does calcium form when it reacts with sodium hydroxide?

Back 1051

White

Front 1052

What coloured precipitate does magnesium form when it reacts with sodium hydroxide?

Back 1052

White

Front 1053

What coloured precipitate does aluminum form when it reacts with sodium hydroxide?

What happens when you add excess aluminium?

Back 1053

White but adding excess sodium makes it dissolve

Front 1054

What precipitate does Copper (II) form after reacting with sodium hydoxide?

Back 1054

Blue

Front 1055

What precipitate does Iron (II) form after reacting with sodium hydoxide?

Back 1055

Green

Front 1056

What precipitate does Iron (III) form after reacting with sodium hydoxide?

Back 1056

Brown

Front 1057

What do metal carbonates contain?

Back 1057

Metal carbonates contain carbonate ions, CO32–.

Front 1058

How can the presence of carbonate ions be detected?

Back 1058

Step 1: Add dilute acid such as sulfuric acid as Carbonates react with dilute acids to produce carbon dioxide and water
Step 2: Collect the gas given off and bubble it through limewater. Limewater is calcium hydroxide solution. It turns cloudy white if carbon dioxide is bubbled through it

Front 1059

What are halide ions?

Back 1059

The ions of the non metals in group 7 of the periodic table

Front 1060

How do you test for halide ions?

Back 1060

1. A few drops of dilute nitric acid are added to the solution
2. A few drops of silver nitrate solution are then added
3. The colour of any precipitate formed is recorded

Front 1061

For chlorine, when its ion is tested for what precipitate is formed and what is its colour?

Back 1061

Silver chloride, AgCl, White

Front 1062

For Bromide, when its ion is tested for what precipitate is formed and what is its colour?

Back 1062

Silver bromide, AgBr, Cream

Front 1063

For Iodide, when its ion is tested for what precipitate is formed and what is its colour?

Back 1063

Silver iodide, AgI, Yellow

Front 1064

How do you test for sulfate ions?

Back 1064

1. A few drops of dilute hydrochloric acid are added to the solution
2 A few drops of barium chloride solution are then added
3. The presence of a white precipitate of barium sulfate shows the presence of sulfate ions in the solution.

Front 1065

Describe the solubility of silver halides?

Back 1065

They are insoluble in water

Front 1066

Describe the process for the halide test?

Back 1066

1. Add aqueous silver nitrate, AgNO3 to an aqueous solution of a halide
2. The silver halide precipitates are different colours
3. Add aqueous ammonia to test the solubility of the precipitate, this is used to tell the colours appart

Front 1067

What colour is silver chloride?

Back 1067

White

Front 1068

What colour is silver bromide?

Back 1068

Cream coloured

Front 1069

What colour is silver iodide?

Back 1069

Yellow

Front 1070

Give the ionic equation of the reaction of chloride with silver?

Back 1070

Ag^+ (aq) + Cl^– (aq) ––> AgCl (s)

Front 1071

Give the ionic equation of the reaction of bromide with silver?

Back 1071

Ag^+ (aq) + Br^– (aq) ––> AgBr (s)

Front 1072

Give the ionic equation of the reaction of iodide with silver?

Back 1072

Ag^+ (aq) + I^– (aq) ––> AgI (s)

Front 1073

Describe the solubility of silver chloride in aqeous ammonia?

Back 1073

Soluble in dilute NH3(aq)

Front 1074

Describe the solubility of silver chloride in aqueous ammonia?

Back 1074

Soluble in concentrated NH3(aq)

Front 1075

Describe the solubility of silver chloride in aqueous ammonia?

Back 1075

Insoluble in concentrated NH3(aq)

Front 1076

What are barium meals used for?

Back 1076

They are meals used to enable doctors to see the outline of the gullet, stomach and upper small intestine to identify abnormalities such as ulcers or tumors

Front 1077

Describe what a barium meal consists of?

Back 1077

Water shaken with barium sulfate

Front 1078

How does a barium meal work?

Back 1078

Barium sulfate, the insoluble comound that forms during the sulfate test is formed. This white precipitate coats the inner lining of the gut. An X–ray is then taken that displays the barium sulfate coating the gut

Front 1079

What is the correct order of tests in quantative analysis for anions?


Give the name of the ion and the formula?

Back 1079

1. Carbonate CO3^2–
2. Sulfate SO4^2–
3. Halides, Cl^– Br^– and I^–

Front 1080

Why is therea correct order to carry out tests of anions in quantative analysis?

Back 1080

Otherwise you could obtain confusing results and make an incorrect identification

Front 1081

In the carbonate test...
1. What do you add?
2. What are you looking for?

Describe incorrect results from other ions you are using quantitive analysis to test for?

Back 1081

1. Dilute acid
2. Effervescence from carbon dioxide
Neither sulfate or halide ions produce bubbles with acid, so it can be carried out without the possibility of an incorrect conclusion

Front 1082

In the sulfate test...

1. What do you add?
2. What are you looking for?


Describe incorrect results?

Back 1082

1. Ba^2+ (aq) ions
2. White precipitate of BaSO4 (s)


BaCO3 is white and insoluble in water, just like BaSO4. If you carry out a sulfate test on a carbonate you will get a white precipitate to. It is important to carry out the carbonate test first and only do the sulfate test when there is no carbonate present

Front 1083

In the halide test...

1. What do you add?
2. What are you looking for?


Describe incorrect results?

Back 1083

1. Ag^+ ions in solution as AgNO3
2. Looking for a precipitate


Silver carbonate and silver sulfate are both insoluble in water and will form as precipitates in this test. Therefore the halide test should be carried out last after carrying out the carbonate and sulfate to wipe out their possibility

Front 1084

How do you analyse the anions in a mixture of chemicals in quatatative analysis?

Back 1084

You carry out the same tests in the same sequence and on the same solution

Front 1085

When carrying out quantative analysis on a mixture of chemicals and ions, what should you do when carrying out the carbonate test?

Back 1085

1. Add dilute nitric acid untill the bubbling stops
2. All carbonate ions will have then been removed and there will be none left to react in the next tests

Front 1086

Describe why, when testing a mixture of chemicals in quantative analysis, why nitric acid should be used to test for carbonate ions?

Back 1086

1. Sulfuric acid contains sulfate ions
2. Hydrochloric acid contains chloride ions
3. These will show up in the sulfate and halide tests but nitric acid will not

Front 1087

When carrying out qualitative analysis on a mixture of chemicals and ions, what should you do when carrying out the sulfate test?

Back 1087

1. From this solution from the carbonate tes, add an excess of Ba(NO3)2 (aq)
2. Any sulfate ions present will precipitate out as barium sulfate
3. Filter the solution to remove the barium sulfate

Front 1088

Describe why, when testing a mixture of chemicals in qualitative analysis, why Ba(NO3)2 should be used to test for sulfate ions?

Back 1088

If you intend to test for halide ions it is important not to use BaCl2 because the chloride ions will show up in the halide test

Front 1089

When carrying out qualitative analysis on a mixture of chemicals and ions, what should you do when carrying out the halide test?

Back 1089

1. To the solution from the sulfate test add AgNO3
2. Any carbonate or sulfate ions initially present have already been removed. Therefore any precipitate formed must be halide ions
3. Add NH3 to confirm which halide you have

Front 1090

What happens when aqueous ammonium ions and aqueouys hydroxide ions react?


Give the equation for this (symbol)?

Back 1090

They form ammonia gas


NH4^+ (aq) + OH^– (aq) ––> NH3 (g) + H2O(l)

Front 1091

How do you test for ammonium ions?

Back 1091

1. Aqeuoys sodium hydroxide is added to a solution of an ammonium ion
2. Ammonia gas is produced
3. The mixture is warmed and the ammonia gas is released
4. You may be able to smell the ammonia or test it with moist pH indicator papers

Front 1092

Why, when carrying out the test for ammonium ions, are no bubbles of ammonia given off?

Back 1092

Because ammonia is very soluble in water

Front 1093

How do you test that ammonia gas is ammonia gas?

Back 1093

1. Smell it
2. Turns moist pH indicator paper blue as it is alkaline

Front 1094

Define the rate of a chemical reaction?

Back 1094

It is a measure of how fast a reactant is being used up or how fast a product is being formed. It is the change in concentration of a reacatn or a product in a given time

Front 1095

What is the equation for the rate of a chemical reaction?

Back 1095

Rate = change in concentration/time

Front 1096

What are the units of change in concentration?

Back 1096

mol dm^–3

Front 1097

What are the units for the rate of reaction?

Back 1097

mol dm^–3s^–1

Front 1098

When in a reaction is the rate of reaction fastest?

Back 1098

At the start as the reactants are at their highest concentrations

Front 1099

Describe the rate of reaction at 1?

Back 1099

At the start of the reaction the reactants are at their highest concentrations and therefore the rate of reaction is greatest

Front 1100

Describe the rate of reaction at 2?

Back 1100

The rate of reaction slows down as the reaction proceeds, because the reactants are being used up and their concentrations decrease

Front 1101

Describe the rate of reaction at 3?

Back 1101

Once one of the reactants has been completely used up, the concentrations stop changing and the rate of reaction is zero

Front 1102

Name four factors that can alter the rate of a chemical reaction?

Back 1102

1. Concentration (or pressure when reactants are gases)
2. Temperature
3. Use of a catalyst
4. Surface area of solid reacants

Front 1103

How do you vary the 'concentration' of a gas?

Back 1103

You change the pressure of it

Front 1104

What does the collision theory state?

Back 1104

That two reacting partciles must collide for a reaction to occur

Front 1105

Describe, usually, the number of collisions in a chemical reaction?


Describe the majority of collisions?

Back 1105

Only a small proportion of collisions result in a chemical reaction




In most collisions, the molecules collide but then bounce off each other and remain chemically unchanged

Front 1106

What are the two conditions that must be met for a collision to be effective and lead to a chemical reaction?

Back 1106

1. The particles collide with the correct orientation
2. The particles have sufficient energy to overcome the activation energy barrier of the reaction

Front 1107

Give the products of this reaction?

Back 1107

No reaction, the two blue atoms must collide for a reaction to occur

Front 1108

Give the products of this reaction?

Back 1108

Front 1109

What happens when you increase the concentration of a reactant in a reaction?

Back 1109

The rate of reaction generally increases

Front 1110

Describe why increasing the concentration increases the rate of reaction?

Back 1110

1. Increases the number of particles in the same volume
2. The particles are closer together and collide more frequently
3. In a given period of time there will be more effective collisions
4. therefore an increased rate of reaction

Front 1111

What happens when you increase the pressure of a reactant in a reaction?

Back 1111

The rate of reaction increases

Front 1112

Describe why increasing the pressure increases the rate of reaction?

Back 1112

1. the concentration of gas molecules increases as the same number of gas molecules occupy a smaller volume
2. The gas molecules are closer together and collide more frequently, leading to more effective collisions in the same time

Front 1113

By which two methods can the progress of a chemical reaction be followed by?

Back 1113

1. Monitoring the removal (decrease in concentration) of a reactant
2. Following the formation (increase in concentration) of a product

Front 1114

What are measurable properties that might change as a rwaction proceeds?

Back 1114

1. Gas volume
2. Mass of reactants or products
3. Colour

Front 1115

If a reaction produces gas, what are the two methods that can be used to determine the rate of reaction?

Back 1115

1. Moniyoring the volume of gas produced at a regular time interval usinggas collection
2. Monitoring the loss of mass of reactants using a balance

Front 1116

What two ways can the volume of gas produced in an experiment be measured?

Back 1116

1. Measuring cylinder
2. Gas syringe

Front 1117

Draw how a measuring cylinder could be used to collect the volume of gas produced from a reaction?

Back 1117

Front 1118

Draw how a gas syringe could be used to collect the volume of gas produced from a reaction?

Back 1118

Front 1119

How do calculate the rate of reaction from the volume of gas produced?

Back 1119

1. Plot a grpah of volume of gas produced against time
2. Draw a tangent at t=0, this is the initial rate
3. Calculate the rate from the gradient of the tangent

Front 1120

What is the equation for the reaction between caclium carbonate and hydrochloric acid?

Back 1120

CaCO3 + 2HCl ––> CaCl2 + CO2 + H2O

Front 1121

Describe how the rate of reaction between calcium carbonate and hydrochloric acid could be dertermined?

Back 1121

1. Carbonate and acid are added to a conical flask
2. The mass of the flask and contents are recorded initially and at regular time intervals
3. Reaction is complete when no more gas is produced so no more mass is lost
4. A graph of mass lost against time is plotted

Front 1122

Define a catalyst?

Back 1122

A substance that changes the rate of a chemical reaction without undergoing any permanent change itself

Front 1123

Describe three features of a catalyst?

Back 1123

1. Not used up in chemical reactions
2. May react with a reactant to form an intermediate or provide a surface on which the reaction can take place
3. At the end of the reaction, the catalyst is regenerated

Front 1124

Name the two ways in which a cataylyst may react with a reactant?

Back 1124

1. Form an intermediate
2. Provide a surface on which the reaction can take place

Front 1125

Define an intermediate?

Back 1125

A species formed during a reaction that reacts further and is not present in the final products

Front 1126

How does a ctalyst increase the rate of a chemical reaction?

Back 1126

By providing an alternative reaction pathway of lower activation energy

Front 1127

Draw the effect of a catalyst on an exothermic reaction on an enthalpy profile diagram?

Back 1127

Front 1128

Draw the effect of a catalyst on an endothermic reaction on an enthalpy profile diagram?

Back 1128

Front 1129

Name two different types of catalysts?

Back 1129

1. Homogeneous catalysts
2. Heterogeneous catalysts

Front 1130

Define a homogeneous catalyst?

Back 1130

A catalyst that has the same physical state as the reactants

Front 1131

Describe what happens when a homogeneous catalyst reacts with a reactant?

Back 1131

It forms an intermediate which then breaks down to give the products and regenerates the catalyst

Front 1132

Give two examples of a homogeneous catalyst?

Back 1132

1. Making esters with sulfuric acid as a catalyst
2. Ozone depletion (Cl O as a catalyst)`

Front 1133

How do you form the ester CH3COOC2H5?

Back 1133

From ethanol and ethanoic acid

Front 1134

Give the equation for the formation of the ester CH3COOC2H5?

Back 1134

C2H5OH + CH3COOH <––> (H2SO4) CH3COOC2H5 + H2O

Front 1135

Give the equation for depletion of ozone?

Back 1135

2O3 <––> 3O2

Front 1136

Define a heterogeneous catalyst?

Back 1136

A catalyst that has a different physical state from the reactants

Front 1137

Describe what happens when a heterogeneous catalyst reacts with a reactant?

Back 1137

They are usually solids in contact with gaseous reactants or reactants in solutions. Reactant molecukes are absorbed (weakly bonded) onto the surface of the catalyst, where the reaction takes place. After reaction, the product molecules leave the surface of the catalyst by desorption

Front 1138

In terms of catalysts what does absorbed mean?

Back 1138

Weakly bonded

Front 1139

Name four common processes using heterogeneous catalysts?

Back 1139

1. Making ammonia
2. Reforming
3. Hydrogenation of alkenes
4. Making sulfur trioxide for sulfuric acid

Front 1140

What is the catalyst for making ammonia?


Give its physical state?

Back 1140

Iron: Fe(s)

Front 1141

What is the catalyst for reforming?

Give its physical state?

Back 1141

Pt (s) or Rh (s)

Front 1142

What is the catalyst for the hydrogenation of alkenes?
Give its physical state?

Back 1142

Ni (s)

Front 1143

What is the catalysts for making sulfur trioxide for sulfuric acid?

Give its physical state?

Back 1143

V2O5 (s)

Front 1144

What is the equation for the reaction to make ammonia?


Give all physical states?

Back 1144

N2 (g) + 3H2 (g) ––> 2NH3 (g)

Front 1145

What is the equation for the reaction for reforming of C6H14?

Give all physical states?

Back 1145

C6H14 (g) ––> C6H12 (g) + H2(g)

Front 1146

What is the equation for the hydrogenation of C2H4?

Give all physical states?

Back 1146

C2H4(g) + H2(g) ––> C2H6(g)

Front 1147

What is the equation for the preparation of sulfur trioxide for sulfuric acid?
Give all physical states?

Back 1147

2SO2(g) + O2 (g) <–––> 2SO3 (g)

Front 1148

Define reforming?

Back 1148

Subjecting hydrocarbons to a catalytic process in which straight–chain molecules are converted to branched forms for use as petrol.

Front 1149

To pass a MOT test what must all vehicles in the UK be fitted with?

Back 1149

A catalytic converter

Front 1150

What do catalytic converters consist of?

Back 1150

A catalyst is made of platinum, rhodium and palladium supported on a honeycomb mesh that provides a large surface area on which reactions can take place

Front 1151

Describe how harmful gases are converted to less harmful products using catalytic converters?

Back 1151

The hot exhaust gases are passed over this heterogeneous catalyst and harmful gases are converted into less harmful products

Front 1152

What two toxic gases are produced in a peterol engine?

Back 1152

Carbon monxide and nitrogen monoxide

Front 1153

In a catalytic converter what is carbon monoxide changed to, by what process?

Back 1153

It is oxidised to carbon dioxide

Front 1154

In a catalytic converter what is nitrogen monoxide changed to, by what process?

Back 1154

It is reduced to nitrogen gas

Front 1155

In a peterol engine what are any unbrunt hydrocarbons converted to, but what process?

Back 1155

They are oxidised to water and carbon dioxide

Front 1156

How do catalysts increase the rate of many industrial chemical reactions?

Back 1156

By lowering the activation energy, this then reduces the temperature needed for the process and the energy requirements

Front 1157

If, due to a catalyst, a chemical process requires less energy, what are the consequences?

Back 1157

1. Chemical process requires less energy
2. Less electricity of fossil fuels are used
3. The product is faster and using less energy
4. Cuts costs and increases profitability

Front 1158

Describe the balance of economic advantageous using a catalyst?

Back 1158

The economic advantages of using a catalyst outweights any costs associated with developing a catalystic process

Front 1159

What are the collisions between moving particles said to be?

Back 1159

Elastic as the molecules do not slow down as a result of a collision and no energy is lost

Front 1160

Describe the spread of moelcular energies i gas, a liquid or solution?

Imagine 3 sections of normal distribution

Back 1160

1. Some molecules move slowly with low energy
2. Some molecules move fast with high energy
3. Most molecules move close to the average speed and have close to the average energy

Front 1161

In which diagram is the spread of molecular energies shown?

Back 1161

The Boltzmann distribution

Front 1162

What symbol represents the activation energy?

Back 1162

Ea

Front 1163

Describe features of the boltzmann distribution?

Back 1163

1. No molecules have zero energy, so the curve starts at the origin

2. The area under the curve is equal to the total number of molecules

3. There is no maximum energy for a molecule, the curve does not meet the x–axis at high energy. The curve would need to reach infinite energy to meet the x–axis

Front 1164

Describe the boltzmann distribution and the line that represents activation energy?

Back 1164

1. Line Ea represents activation energy

2. The shaded area shows the molecules that have energy more than Ea

3. Only a small number of molecules have the energy to react

Front 1165

Describe why there is a change in the curve when the temperature increases from T1 to T2?

Back 1165

1. As temperature increases, the average energy of the molecules also increases

2. A small proportion of molecules will still have low energy

3. More molecules have higher energy

4. The graph is now stretched over a greater range of energy values

5. The peak of the graph is lower on the y–axis and further along the x–axis because the peak is at a higher energy level

6. The number of molecules remains the same so the area under the curve remains the same

Front 1166

Describe the movement of molecules at the increased temperature shown?

Back 1166

1. At a higher temperature, more molecules have a energy greater than or equal to the activation energy

2. Therefore, a greater proportion of collisions will lead to a reaction, increasing the rate of reaction

3. Collisions will be more frequent as the molecules are moving faster

Front 1167

Draw the affect of adding a catalyst to the boltzmann distribution?

Back 1167

Front 1168

Draw the effect of increasing the temperature to the boltzmann distribution?

Back 1168

Front 1169

At a higher temperature...


(Bmann distribution)

Back 1169

a greater proportion of molecules can overcome the activation energy

Front 1170

In the presence of a catalyst...


(Bmann distribution)

Back 1170

a greater proportion of molecules exceeds the new lower activation energy

Front 1171

Describe the effect of the addition of a catalyst?

Back 1171

1. Provides a reaction route with a lower activation energy

2. A greater proportion of molecules now have energy equal to, or greater than the lower activation energy

3. On collision, more molecules will react to form products

4. The result is an increase in the rate of reaction

Front 1172

2H2 + O2 ––>

Back 1172

2H2O

Front 1173

What are reversible reactions?

Back 1173

Reactions that take place in boththe forward and reverse direction

Front 1174

Draw the reversible reaction symbol?

Back 1174

Front 1175

What does this symbol show?

Back 1175

A reversible reaction

Front 1176

What are the properties of an equilibrium system?

Back 1176

1. The rate of the forward reaction is equal to the rate of the reverse reaction
2. The concentrations of reactants and products do not change

Front 1177

Define a dynamic equilibrium?

Back 1177

A dynamic equilibrium is a chemical equilibrium between a forward reaction and the reverse reaction where the rate of the reactions are equal.

Front 1178

Describe the rate of formation of porducts and reactants in a dynamic equilibrium?


What does this mean in terms of concentration?

Back 1178

As fast as the reactants are becoming products, the products are reacting to become reacants.


The concentrations of the reactants and the products remains unchanged, even though the forwards and reverse reactions are taking place

Front 1179

For a reaction to remain in equilibrium what conditions must it be kept under?

Back 1179

The system must be closed

Front 1180

Define a closed system?

Back 1180

A system isolated from its surrondings, so the temperature, pressure and concentrations of reactants and products are unaffected by outside infleunces

Front 1181

What does the position of equilibrium indicate?

Back 1181

The extent of the reaction

Front 1182

What happens to the position of equilibium if the temperature, oressure on concentration changes?

Back 1182

Then the position of equilibrium many change

Front 1183

What does le Chateliers principle state?

Back 1183

That when a system in equilibrium is subjected to an external change, the system readjusts itself to minimise the effect of that change

Front 1184

What is the name given to the principle that: 'When a system in equilibrium is subjected to an external change, the system readjusts itself to minimise the effect of that change'

Back 1184

le Chateliers principle

Front 1185

If an equilibrium is disrputed by adding more reactant molecules, what happens?

Back 1185

The position of the equilibium shifts to the right of the equation. More products are made than reactants untill a new equilibrium is established

Front 1186

Name four things that can change an equilibrium?

Back 1186

1. Concentration
2. Temperature
3. Pressure
4. Catalyst

Front 1187

If there are more products formed, how does the position of equilibrium change?

Back 1187

It shifts to the right

Front 1188

If there are more reactants formed as a consequence of the POE changing, in what direction does the position equilibrium shift?

Back 1188

It shifts to the left

Front 1189

How can you investigate changes of the position of equilibrium with concentration?

Back 1189

Using equilibria where reactants and products have different colours

Front 1190

A + B <–––> C + D


What happens when you increase the concentration of A or B?

Back 1190

The equilibrium shifts to the left to balance the decrease of C or D and restore an equilibrium

Front 1191

A + B <–––> C + D

What happens when you increase the concentration of C or D?

Back 1191

Because there is an increase in the concentration of C or D there is a decrease in the concentration of A or B, therefore the equilibrium shifts to the left to balance this change

Front 1192

Name one equation that displays colour changes with changing concentration at equilibria?

Clue: oxidation

Back 1192

The equilibrium between aqueous chromate ions, CrO4^2– and dichromate ions Cr2O7^2–:
2CrO4^2– + 2H^+ <––> C2O7^2– + H2O

Front 1193

What is the colour of crhomate ions?

Back 1193

Yellow

Front 1194

What is the colour of dichromate ions?

Back 1194

Orange

Front 1195

What happens if you add hydrogen ions to this equilibria?


2CrO4^2– + 2H^+ <––> C2O7^2– + H2O

Back 1195

There will be more of A/B so there will be a shift to the left to balance this change, changing the colour to orange

Front 1196

What happens if you add water to this equilibria?

2CrO4^2– + 2H^+ <––> C2O7^2– + H2O

Back 1196

There will be more of C/D so there will be a shift to the right, changing the colour to yellow

Front 1197

If you have yellow K2CrO4 in a beaker, what could you add to make it orange?


What could you add to make it yellow again?

Back 1197

Dilute sulfuric acid: H2SO4


Aqueous sodium hydroxide: NaOH

Front 1198

Why does adding H2SO4 change K2CrO4 from yellow to orange?

Back 1198

1. Increases the concentration of H^+ ions
2. Increases the rate of the forward reaction
3. Decreases the concentration of the added reaction
4. A new position of equilibrium is established towards the products so it is organe

Front 1199

Why does adding NaOH change to CrO4^2– from orange to yellow?

Back 1199

1. Decreased concetration of H^+ ions as the OH^– ions reaction with them to form H2O:
H^+ + OH^– ––> H2O
2. Decreased concentration of reactant, decreases the rate of the forward reaction
3. Shift to the left making more of the H^+ reactant that has been removed
4. A new position of equilibrium has formed towards the reactant so it is yellow

Front 1200

Describe the values of the enthalpy change in reversible reactions?

Back 1200

The forward and reverse reactions have the same value for enthalpy change but different signs +/–

Front 1201

What does an increase in temperature do to an equilibrium?

Back 1201

It shifts it to the endothermic direction (Delata H is positive) as energy is taken in to minimise the effect of the temperature change

Front 1202

What does an decrease in temperature do to an equilibrium?

Back 1202

It shifts it to the exothermic direction (Delta H is positive) as energy is lost to minimise the effect of the temperature change

Front 1203

What colour does cobalt chloride form when disoolved in water?

Back 1203

Pink solution

Front 1204

What does the dissolving process of cobalt chloride produce?


Give the equation?

Back 1204

An equilibrium between two complexes of cobalt that are different colours


[Co(H2O)6]^2+ + 4Cl^– <–––> CoCl4^2– + 6H2O

Front 1205

What cobalt complex is pink?

Back 1205

[Co(H2O)6]^2+ + 4Cl^–

Front 1206

What cobalt complex is blue?

Back 1206

CoCl4^2– + 6H2O

Front 1207

[Co(H2O)6]^2+ + 4Cl^– <–––> CoCl4^2– + 6H2O

Draw arrows to label the exothermic and endothermic direction?

Back 1207

[Co(H2O)6]^2+ + 4Cl^– <–––> CoCl4^2– + 6H2O

<–––––– Delta H is negative

Front 1208

Give an example of a reaction which is sensitive to temperature changes and changes colour to investigate the position of equilibrium with temperature?
Give the equation?

Back 1208

Dissolving cobalt chloride in water


[Co(H2O)6]^2+ + 4Cl^– <–––> CoCl4^2– + 6H2O

Front 1209

Describe the experiment to show the colour changes of cobalt chloride dissolved in water with temperature changes?

Back 1209

1. Dissolve cobalt chloride in water in a boiling tube
2. Add HCL and place tube in some iced water, it is a pink colour
3. Set up a boiling water bath and transfer the boiling tube into the water. The solution turns a blue colour
4. Transfer the boiling tube back to the iced water and it will change back to pink

Front 1210

Why does the colour of cobalt chloride dissolved in water change from pink to blue when it is placed in boiling water?

Back 1210

1. You are increasing the heart energy of the system
2. This causes the position of equilibrium to shift to minimise the change
3. As the forwards reaction is endothermic, the position of equilibrium shifts to the right to take heat energy in and minimise the increase in temperature
4. The solution turns a blue colour

Front 1211

Why does the colour of cobalt chloride dissolved in water change from blue to pink when it is placed in iced water?

Back 1211

1. You are decreasing the heart energy of the system 2. This causes the position of equilibrium to shift to minimise the change
3. As the backwards reaction is exothermic, the position of equilibrium shifts to the left to put heat energy out and minimise the decrease in temperature
4. The solution turns a pink colour

Front 1212

If the forwards reaction is exothermic and you increase the temperature, what happens?

Back 1212

Position of the equilibrium shifts to the left and more reactants are made

Front 1213

If the forwards reaction is exothermic and you increase the temperature, what happens?

Back 1213

Position of equilibrium shifts to the left and more reactants are made

Front 1214

If the forwards reaction is exothermic and you increase the temperature, what happens?

Back 1214

Position of equilibrium shifts to the left and more reactants are made

Front 1215

If the forwards reaction is exothermic and you increase the temperature, what happens?

Back 1215

Position of the equilibrium shifts to the left and more reactants are made

Front 1216

What result does changing the pressure of a system containg an equilibrium of gases result in?


When does this ONLY apply?

Back 1216

It results in the position of equilibrium changing


If there are more gaseous molecules on one side of the equation that the other

Front 1217

What olour is nitrogen dioxide (NO2)?

Back 1217

Brown

Front 1218

What colour is Dinitrogen tetroxide (N2O4)?

Back 1218

Colourless

Front 1219

Give the equation of the dynamic equilibrium between nitrogen dioxide and dinitrogen tetroxide?

Back 1219

2NO2 <––––> N2O4

Front 1220

Describe the relationship between the pressure and concentration of a gas?

Back 1220

They are proportional. Two moles of one gas has twice the preesure as the same container holding one moles of another gas

Front 1221

What happens when you increase the pressure of a system at equilibria?

Back 1221

The position of equilibrium will shift to the side with fewever molecules, reducing the pressure of the system

Front 1222

In this reaction: 2NO2 <–––> N2O4


What does increasing the pressure do?

Back 1222

1. Shift the equilibrium to the side with fewer molecules – the right hand side. This reduces the number of gaseous moles to minimise the increase in pressure
2. More colourless N2O4 is formed and the brown colour fades

Front 1223

In this reaction: 2NO2 <–––> N2O4

What does decreasing the pressure do?

Back 1223

1. Shift the equilibrium to the side with the most molecules – the left hand side. This increases the number of gaseous moles to minimise the decrease in pressure 2. More brown NO2 is formed and the solution because coloured

Front 1224

Describe the effect on the position of equilibrium a catalyst has?

Back 1224

It does not change it

Front 1225

Describe the effect of a catalyst on equilibrium?

Back 1225

It speeds up the rates of the forward and revserve reactions equally. It also increases the rate at which an equilibrium is established

Front 1226

Describe the effect of a catalyst on the rate an equilibrium is established?

Back 1226

It increases the rate

Front 1227

Give the equation for the Haber process?

Back 1227

N2(g) + 3H2(g) <–––> 2NH3

Front 1228

What can le chateliers principle be used to predict in industry?

Back 1228

The best conditions of temperature and pressure to force the equilibrium to the right to produce the maximum yield of ammonia

Front 1229

What is the best conditions for the Haber process to produce ammonia? Not specifics... IDEAL

Back 1229

1. Low temperature to push the equilibrium to the right
2. High pressure to push the equilibrium to the right

Front 1230

Why shouldn't a low temperature be used in the Haber process even if this would produce the maximum yeild of ammonia?

Back 1230

1. Produced a high yeild of product but slowly
2. The rate may be so slow that an equilibrium may not be established

Front 1231

Why shouldn't a high pressure be used in the Haber process even if this would produce the maximum yield of ammonia?

Back 1231

1. Increases the yield, the concentration and therefore the rate of reaction
2. Requires a very strong container and large quantity of energy
3. Increases the costs of the process
4. Safety, failure in steelwork could lead to toxic ammonia leaking under pressure

Front 1232

What type conditons does a typical ammonia plant operate under?

Back 1232

Compromise conditions:
1. High enough temperature to give a reasonable rate of reaction without shifting the position too far away from ammonia
2. Iron catalyst used to speed up the reaction so lower temperatures can be used

Front 1233

What specific conditions does a typical ammonia plant operate under?

Back 1233

350 – 500 degrees celsius
100 – 200 atm

Front 1234

What is the percentage of nitrogen and hydrogen converted to ammonia?


Describe why this is not a problem?

Back 1234

15%


Unreacted reactants are recycled so nearly all of the nitrogen and hydrogen is eventually converted into ammonia

Front 1235

What does an eqilibrium constant provide?

Back 1235

The actual position of an equilibrium

Front 1236

What does the magnitude of an equilibrium constant show?

Back 1236

Whether there are more reactants or more products in an equilibrium system

Front 1237

Write the equation for a general reversible reaction?


From this write the equilibrium law?

Back 1237

aA + bB <–––> cC + dD


Kc = [C]^c x [D]^d/[A]^a x [B]^b

Front 1238

aA + bB <–––> cC + dD

In this what is represented by...
a) Capital letters
b) Lower case letters

Back 1238

a) The equilibrium concentrations of the reactants and products
b) The balancing numbers in the overall equation

Front 1239

What letters go ontop of the equilbrium law?

Back 1239

The products

Front 1240

What letters go on the bottom of the equilibrium law? (K=)

Back 1240

The reactants

Front 1241

What, in the equilibrium law are the square brackets [] responsible for?

Back 1241

They represent the shorthand for 'concentration of'

Front 1242

Write the equilibrium expression (Kc) for this eqaution:


N2 (g)+ O2(g) <–––> 2NO (g)

Back 1242

Kc = [NO]^2/[N2(g)]^1 x [O2]^1

Front 1243

Calculate Kc for the following equilibrium:
H2(g) + I2(g) <–––> 2HI


The concentrations are:
[H2] = 8.00 x 10^–4
[I2] = 1.20 x 10^–4
[HI] = 2.28 x 10^–3

Back 1243

Kc = [HI]^2/[H2(g)]^1 x [I2]^1

Kc = [2.28x10^–3]^2/[8.00x10^–4]^1 x [1.20 x 10^–4]^1



=54.2

Front 1244

What does a Kc value of 1 indicate?

Back 1244

A position of equilibrium that is halfway between reactants and products

Front 1245

What does a Kc value greater than one tell us?

Back 1245

A position of equilibriym that is towards the products

Front 1246

What does a Kc value less than one tell us?

Back 1246

A position of equilibrium that is towards the reactant

Front 1247

The larger the Kc value...

Back 1247

...the further the position of equilibrium lies to the right–hand side and the greater the concentrations of the products compared to the reactants

Front 1248

Define the term atomic number?

Back 1248

The number of protons in an atom

Front 1249

Define the term mass number?

Back 1249

The number of protons and neutrons in an atom

Front 1250

What is an atom?

Back 1250

The smallest components of an element showing its chemical properties

Front 1251

What is the relative mass of an electron?

Back 1251

1/1836

Front 1252

What is an isotope?
What stays the same in an isotope?

Back 1252

Isotopes are different forms of the same atom with different numbers of neutrons.


The number of protons always stays the same, otherwise it is not the same element.

Front 1253

What does different numbers of neutrons do and not do?

Back 1253

It changes the physical properties of an element but not its chemical properties

Front 1254

What is heavy water?

Back 1254

Heavy water is used in nuclear powerplants and uses heavier forms of hydrogen to make it

Front 1255

Descibe the differance between ice made with heavy water and regular water?

Back 1255

Heavy water has a higher density and so the ice will sink but regular water will float because its structure gives it a lower density than water

Front 1256

The number in the name of different isotopes represents the elements what....?

Back 1256

Mass number (number of protons and neutrons)

Front 1257

What does A stand for? (Not arhhenius)

Back 1257

The atomic number

Front 1258

What does z stand for?

Back 1258

The mass number

Front 1259

What does P+ stand for?

Back 1259

Proton

Front 1260

What does e– stand for?

Back 1260

Electron

Front 1261

What does n stand for? (Atom)

Back 1261

Neutron

Front 1262

Why is the mass of chlorine in the periodic table 35.5?

Back 1262

Because it takes an average of the mass of both chlorine–35 and chlorine–37, taking into account their relative abundance, of which chlorine–37 is lower and chlorine–35 is higher, therefore making the average 35.5

Front 1263

What is a cation?

Back 1263

When welectrons are lost from an atom, forming a positively chanrged ion

Front 1264

What is a positively charged ion called?

Back 1264

A cation

Front 1265

What is an anion?

Back 1265

When electrons are lost from an atom forming a negatively charged ion

Front 1266

What is a negatively charged ion called?

Back 1266

An Anion

Front 1267

What are cations typically?

Back 1267

Metals

Front 1268

What are anions typically?

Back 1268

Non metals

Front 1269

What is an isoelectron?

Back 1269

They are different elements as they have different numbers of protons and neutrons but the same number of electrons because they have lost or gained them

Front 1270

What are elements with different numbers of protons and neutrons but the same number of electrons called?

Back 1270

Isoelectrons

Front 1271

What does m/z mean?

Back 1271

mass/charge

Front 1272

What are the two axis on a mass spectra graph?

Back 1272

Mass over charge (along the bottom)
% abundance (along the side)

Front 1273

What is the formula for calaculating the Ar (reltaive atomic mass) from a mass spectra?

Back 1273

(% abundance x mass) + (% abundance x mass)

Front 1274

What is the mass spectrometry process?

Back 1274

1. Sample is placed in the mass spectrometer
2. The sample is vaporised and then ionised to form positive ions
3. The ions are accelerated, heavier ions move more slowly and are more difficult to deflect that lighter ions. So the ions of each isotope are separated
4. The ions are detected on a mass spectrum. Each ion reaching the detector adds to the signal so the greater the abundance the larger the signal

Front 1275

Describe the conditions of the interior of a mass sepectrometer?

Back 1275

Its kept under a vacum to allow the ions to move at high speeds because they will not collide with atoms in the air.
It is also kept at a low pressure

Front 1276

What is the formula for ammonium?

Back 1276

NH4

Front 1277

What is the charge on ammonium?

Back 1277

1+

Front 1278

What is the formula for hydroxide?

Back 1278

OH

Front 1279

What is the charge on hydroxide ions?

Back 1279

1–

Front 1280

What is the formula for nitrate?

Back 1280

NO3

Front 1281

What is the charge on a nitrate ion?

Back 1281

1–

Front 1282

What is the formula for a nitride ion?

Back 1282

NO2

Front 1283

What is the charge on a nitride ion?

Back 1283

1–

Front 1284

What is the formula for an ion of hydrogencarbonate?

Back 1284

HCO3

Front 1285

What is the charge on an ion of hydrogencarbonate?

Back 1285

1–

Front 1286

What is the formula for an ion of manganate (VII) (permanganate)?

Back 1286

MnO4

Front 1287

What is the charge of a manganate (VII) (permanganate) ion?

Back 1287

1–

Front 1288

What is the formula for a carbonate ion?

Back 1288

CO3

Front 1289

What is the charge on a carbonate ion?

Back 1289

2–

Front 1290

What is the formula for a sulfate ion?

Back 1290

SO4

Front 1291

What is the charge on a sulfate ion?

Back 1291

2–

Front 1292

What is the formula of a sulfite ion?

Back 1292

SO3

Front 1293

What is the charge on a sulfite ion?

Back 1293

2–

Front 1294

What is the formula for a dichromate (VI) ion?

Back 1294

Cr2O7

Front 1295

What is the charge on a dichromate (VI) ion?

Back 1295

2–

Front 1296

What is the formula for a phospate ion?

Back 1296

PO4

Front 1297

What is the charge on a phosphate ion?

Back 1297

3–

Front 1298

What is the negligible mass of an electron?

Back 1298

1/1836 of a proton

Front 1299

Where is nearly all the mass of an atom?

Back 1299

In the nucelus

Front 1300

What is the role of neutrons in the nucleus?

Back 1300

They hold the nuceleus together despite the electrostatic repulision between its positively charged protons

Front 1301

Describe the number of neutrons in the nucelus? Not isotopes

Back 1301

1. Most atoms contain the same number of, or slightly more neutrons than protons
2. As the nucelus gets larger more and more neutrons are needed

Front 1302

What identifies an element?

Back 1302

The number of protons in an atom

Front 1303

Describe atoms of the same element?

Back 1303

Every atom of the same element has the same numbers of protons

Front 1304

Describe atoms of different elements?

Back 1304

Different atoms contain different numbers of protons

Front 1305

What are isotopes?

Back 1305

They are atoms of the same element with different numbers of neutrons and different masses

Front 1306

What are most elements made up of?

Back 1306

A mixture of isotopes

Front 1307

What represents the mass number of an isotope? Symbol
What represents the atomic number of an isotope? Symbol

Back 1307

A
Z

Front 1308

Describe isotopes and the way in which they react?

Back 1308

1. Different isotopes of the saem element have the same number of electrons
2. The number of neutrons has no effect on the reactions of an element
3. Different isotopes of an element therefore react in the same way

Front 1309

What is an ion?

Back 1309

It is a charged atom. This is formed from the loss or gain of electrons and because the number of electrons is different to the number of protons

Front 1310

What are positive ions also called?


Describe positive ions?

Back 1310

Cations


They are atoms with fewer electrons than protons. They have an overall positive charge

Front 1311

What are negative ions called?


Describe negative ions?

Back 1311

They are called anions


They are atoms with more electrons than protons. They have an overall negative charge

Front 1312

Describe the strong nuclear forces within an atom and the consequence of this?

Back 1312

The strong nuclear forces holding together protons and neutrons results in the loss of a fraction of their mass. This is called the mass defect

Front 1313

What is the role of carbon–12?

Back 1313

It is the standard isotope which is the international standard for the measurement of atomic masses

Front 1314

What is an atomic mass unit?

Back 1314

u

Front 1315

What is the mass of carbon 12?

Back 1315

12 u (atomic mass units)

Front 1316

What is the standard mass of atomic mass and how does this relate to carbon–12?

Back 1316

The standard mass for atomic mass is 1u, the mass of 1/12th of an atom of carbon–12

Front 1317

What is the definition of relative atomic mass?

Back 1317

It is the weighted mean mass of an atom of an element relative to 1/12th the mass of an atom of carbon–12

Front 1318

What does the weighted mean mass of an element take into account?

Back 1318

1. The percentage abundance of each isotope
2. The relative isotopic mass of each isotope

Front 1319

What equipment is used to find the percentage abundances of the isotopes in a smaple of an element?

Back 1319

Using a mass spectrometer

Front 1320

What is the mass to charge ratio?

Back 1320

It is how the ions are detected on a mass to charge ratio


m/z


relative mass of an ion/relative charge on an ion

Front 1321

What is a binary compound?

Back 1321

It contains only two elements

Front 1322

How do you name a binary compound?

Back 1322

1. The metal ion comes first
2. Change the ending of the second elements name to –ide

Front 1323

List the diatomic molecules?

Back 1323

H2, N2, O2, F2, CL2, BR2, I2

Front 1324

Give the forula of phosphorus and sulfur?

Back 1324

P4 and S8 (in pratice sulfur is just written as S

Front 1325

What is the formula unit?

Back 1325

The formula worked out from the ionic charges of ionic compounds

Front 1326

What is the shell number of energy level called?

Back 1326

The quantum number/level

Front 1327

What are shells made up of?

Back 1327

Shells are made of atomic orbitals.

Front 1328

Describe atomic orbitals (5 points)

Back 1328

1. Regions around the nucelus that can hold up to two electrons with opposite spins.
2. Atomic orbitals are regions where there is a high probability of finding an electron
3. Can hold 1 or 2 electrons
4. There are s–, p–, d– and f– orbitals
5. Each orbital has a different shape

Front 1329

Describe s–orbitals?

Back 1329

1. The shape is of a sphere
2. Each shell from quantum level 1 contains 1s orbital
2.The greater the shell number the greater the radius of the s orbital

Front 1330

Describe p orbitals?

Back 1330

1. The electron cloud is in the shape of a dumb–bell
2. There are three separate p orbitals at right angles to each other, called Px, Py and Pz
3. Each shell from quantum level 2 contains three p orbitals
4. The greater the shell number, the further the p–orbital is from the nucleus

Front 1331

Describe d orbitals?

Back 1331

Each shell from quantum level 3 contains five d orbitals

Front 1332

Describe quanutm level f?

Back 1332

Each shell from quatum level 4 conatins seven f orbitals

Front 1333

How are obitals grouped together?

Back 1333

As sub shells

Front 1334

How mnay electrons can fit in the sub shell or an...


1. S orbital
2. P orbital
3. D orbital
4. F orbital

Back 1334

1. 2
2. 6
3. 10
4. 14

Front 1335

Describe the energy levels of quantum level 2 sub shells?

Back 1335

Each new sub shell added has a higher energy. In the second shell the 2p sub shell has a higher energy level that the 2s sub shell

Front 1336

Describe the energy level of the quantum level 3d sub shell and 4s?

Back 1336

1. The highest energy level in the third and the lowest energy in the fourth shell overlap
2. The 3d subshell is at a higher energy level than a 4s sub shell
3. The 4s subshell therefore fills before the 3d subshell
4. The order of filling is therefore 3p, 4s, 3d

Front 1337

Describe electrons and electron spin?

Back 1337

1. Electrons are negatively charged and repel one another
2. They have a property called spin – either up or down
3. An electron is shown as an arrow, indicating the direction of its spin
4. The two electrons in an orbital must have opposite spins

Front 1338

Why must two electrons in a sub shell have opposite spins?

Back 1338

Because the oppositecharged help to counteract the repulision between the negative charges of the two electrons

Front 1339

Describe the filling of orbitals and electron spin diagrams?

Back 1339

1. The orbitals have the ame energy
2. One electron occupies each orbital before pairing starts
3. This prevents any repulsion between paired electrons until there is no further orbital available at the same energy level

Front 1340

Where is D Block on the periodic table?

Back 1340

Front 1341

Where is S Block on the periodic table?

Back 1341

And helium

Front 1342

Where is F Block on the periodic table?

Back 1342

Front 1343

Where is P Block on the periodic table?

Back 1343

Front 1344

Describe ions and the 4s shell?

Back 1344

1. The 4s sub shell is at a lower energy level than the 3d sub shell so it is filled first
2. The 4s sub shell also empties before the 3d sub shell

Front 1345

Describe the energy level of the 3d and 4s sub shells once filled?

Back 1345

The energies of the 3d and 4s sub shells are very close together and once filled the 3d energy level falls below the 4s

Front 1346

Here is the electronconfiguration of the nickel atom:


1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8


Describe the electronic configuration of a Ni^2+ ion

Back 1346

1s^2 2s^2 2p^6 3s^2 3p^63d^8

This is because the 4s shell empties before the 3d sub shell

Front 1347

Which two elements in the d block have special properties?

Back 1347

Copper and Chromium

Front 1348

Describe the electron configuration of copper?

Back 1348

Electron spin attempts tom combat the repulsive charges between negatively charged electrons. Therefore copper fills such that


[Ar]4s1 3d5


The 3 fills an extra electron and the 4 loses one

Front 1349

Describe the electron configuration of chromium?

Back 1349

Electron spin attempts to combat the repulsive charges between negatively charged electrons. Therefore chromium fills such that
[Ar]4s1 3d5
The 3 fills an extra electron and the 4 loses one

Front 1350

What is ionic bonding?

Back 1350

It is the electrostatic forces of attraction between positive and negative ions. It holds together cations and anions

Front 1351

What do you need to rember to do when drawing a dot and cross diagram?

Back 1351

Put the brackets round the outside

Front 1352

Describe the structure of ionic bonds?

Back 1352

1. Each ion attracts oppositley charged ions in all directions
2. This forms a giant ionic lattice containing billions of ions
3. The number of ions is determined by the size of the crystal

Front 1353

Describe the physcial properties of ionic compounds?

Back 1353

1. High melting and boiling points
2. Depends on the compounds – but they tend to dissolve
3. As a solid they do not conduct electricity
4. As molten or dissolved they conduct electricity

Front 1354

Describe ionic compounds and their melting and boiling points? Therefore describe their state at room temperature using intermolecular forces

Back 1354

1. Most are solid at room temperature
2. This is because there is insufficient energy to overcome the strong electrostatic forces of attraction between the oppositely charged ions
3. High temperatures are needed to provide this quantity
4. They therefore have high melting and boiling points

Front 1355

Describe the melting and boiling points for lattices conatining ions with greater ionic charges?

Back 1355

The greater the charge the more energy is required required to overcome them so therefore they have a higher melting and boiling point than a ionic compound consisting of a lattice with a lesser charge

Front 1356

What does ionic attraction depend upon?

Back 1356

1. The quanitity of charge on an ion
2. The size of the ions

Front 1357

Describe ionic compounds and solubility?

Back 1357

1. Many ionic compounds dissolve in polar solvents such as water
2. The polar water molecules break down the lattice and surround each ion in solution
3. In a compound made of ions with large charges the ionic attraction may be too strong for the water to break down the lattice structure so the compound is not very soluble

Front 1358

What are the two main processes for solubility of ionic lattices?

Back 1358

1. The ionic lattice must be broken down
2 The water molecules must attract and surrond the ions

Front 1359

What does the solubility of an ionic compound depend upon to happen?

Back 1359

1. The relative strengths of the attractions within the giant ionic lattice
2. The attractions between ions and water molecules

Front 1360

Describe ionic compounds and electrical conductivity?

Back 1360

1. In a solid state an ionic compound does not conduct electricity
2. Once melted the ionic compound does conduct electricity

Front 1361

Why can electricity not be conducted in a solid state of ionic lattice?

Back 1361

1. The ions are in a fixed position in the gaint lattice
2. There are no mobile charge carriers

Front 1362

Why can electricity be conducted in a liquid state of ionic lattice?

Back 1362

1. The solid ionic lattice breaks down
2. The ions are now free to move as mobile charge carriers
3. This means an ionic compound is a conductor of electricity in liquid and aqueous states

Front 1363

What is covalent bonding?

Back 1363

It is the strong electroststic attraction between a shared pair of electrons and the nuclei of bonded atoms

Front 1364

In which atoms does covalent bonding take place?

Back 1364

1. Non metallic elements
2. Compounds of non metallic elements
3. Polyatomic ions

Front 1365

What are pairs of electrons that are not shared in covalent bonds called?

Back 1365

Lone pairs of electrons

Front 1366

How mnay bonds does carbon form


How many bonds does oxygen form?

Back 1366

4 bonds


2 bonds

Front 1367

How many bonds does nitrogen form?




How many bonds does hydrogen form?

Back 1367

3 bonds


1 bond

Front 1368

Describe a double bond in terms of electrons?

Back 1368

1. The electrostatic forces of attraction are between two shared pairs of electrons and the nuceli of the bonding atoms
2. All atoms have 8 electrons in their outer shell

Front 1369

Describe tripple covalent bonds?

Back 1369

1. The electrostatic attraction is between three shared pairs of electrons and the nuclei of bonding atoms
2. All atoms have the structure of the nearest nobel gas

Front 1370

What is a dative covalent bond?

Back 1370

It is a covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only

Front 1371

What is a dative covalent bond also called?

Back 1371

A coordinate bond

Front 1372

What is covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only called?

Back 1372

A dative covalent bond

Front 1373

Describe the electrons in dative covalent bonds?

Back 1373

The shared pair of electrons by the sole bonding atom was originally a lone pair of electrons.

Front 1374

What symbol indicates a dative covalent bond?

Back 1374

an arrow from the sole bonding atom to the atom which gains electrons

Front 1375

What is an oxidising agent?

Back 1375

An oxidizing agent is a substance that has the ability to oxidize other substances (cause them to lose electrons)

Front 1376

How many electrons are there in a....
1. S orbital
2. P orbital
3. D orbital
4. F orbital

Back 1376

1. 2
2. 6
3. 10
4. 14

Front 1377

Define an orbital?

Back 1377

Atomic orbitals are regions of space around the nucleus of an atom where an electron is likely to be found.

Front 1378

Define a covalent bond?

Back 1378

A shared pair of electrons, one electron being supplied by each atom either side of the bond.

Front 1379

What is the forumla of propene?

Back 1379

C3H6

Front 1380

What is another name for a dative covalent bond?

Back 1380

A co–ordinate bond

Front 1381

Describe the differences between silicon dioxide and carbon dioxide?

Back 1381

1. Silicon dioxide is a macromoleucle, carbon dioxide is a simple covalent substance.
2. Silicon atoms in silicon dioxide are bonded to four other oxygen atoms, forming the crystal structure whereas carbon dioxide exists as lone molecules which are joined together by weak covalent bonds

Front 1382

Describe electron pair replusion theory?

Back 1382

1. An electron has a negative chage so electron pairs repel one another
2. Model used in chemsitry for expalining and predicitng the shaopes of molecules and polyactomic ions

Front 1383

Describe the laws of the electron pair repulision theory?

Back 1383

1. The electorn pairs surronding a central atom determine the shape of the molecule or ion
2. The elctron pairs repel one another so they are arranged as far apart as possible
3. The arrangement of electron pairs minimises repulision and thus holds the bonded atoms in a defintie shape
4. Different numbers of electron pairs result in different shapes

Front 1384

What does this line represent in terms of shapes of molecules?

Back 1384

A bond in the plane of the paper

Front 1385

What does this line represent in terms of shapes of molecules?

Back 1385

A bond that comes out of the plane of the paper

Front 1386

What does this line represent in terms of shapes of molecules?

Back 1386

A bond that goes into the plane of the paper

Front 1387

Describe lone electrons and their positioning?

Back 1387

1. Slightly closer to the central atom
2. Occupy more space than a bonded pair

Front 1388

Describe the main difference between bonding and lone pairs?

Back 1388

Lone pairs repel more strongly than a bonded pair

Front 1389

Describe the relative repulsions between lone and bonding pairs?

Back 1389

1. Bonded/bonded pair
2. Bonded pair/lone pair
3. Lone pair/lone pair (Strongest repulsion)

Front 1390

Draw a triangular bipyramidal?

Back 1390

Front 1391

Draw an octahedral?

Back 1391

Front 1392

Draw a linear?

Back 1392

Front 1393

Draw a trigonal Planar?

Back 1393

Front 1394

Draw a tetrahedral?

Back 1394

Front 1395

What is the name of the shape of a molecule with 2 electron pairs?


What are the bond angles?

Back 1395

Linear


180 degrees

Front 1396

What is the name of the shape of a molecule with 3 electron pairs?


What are the bond angles?

Back 1396

Trigonal Planar


120 degrees

Front 1397

What is the name of the shape of a molecule with 4 electron pairs?


What are the bond angles?

Back 1397

Tetrahedral


109.5 degrees

Front 1398

What is the name of the shape of a molecule with 5 electron pairs?


What are the bond angles?

Back 1398

Triangular Bipyramid


90 and 120 degrees

Front 1399

What is the name of the shape of a molecule with 6 electron pairs?


What are the bond angles?

Back 1399

Octahedral


90 degrees

Front 1400

What shape is CH4 (methane)?

Back 1400

It has four bonding pairs so is tetrahedral

Front 1401

What is the name of the shape with 2 bonding pairs and 1 lone pair?

Back 1401

Bent

Front 1402

What is the name of the shape with 3 bonding pairs and 1 lone pair?

Back 1402

Trigonal pyramidal

Front 1403

What is the name of the shape with 2 bonding pairs and 2 lone pairs?

Back 1403

Non–linear or bent

Front 1404

What is the name of the shape with 4 bonding pairs and 1 lone pair?

Back 1404

Seesaw

Front 1405

What is the name of the shape with 3 bonding pairs and 2 lone pairs?

Back 1405

T–shaped

Front 1406

What is the name of the shape with 2 bonding pairs and 3 lone pairs?

Back 1406

Linear

Front 1407

What is the name of the shape with 5 bonding pairs and 1 lone pairs?

Back 1407

square pyramidal

Front 1408

What is the name of the shape with 4 bonding pairs and 2 lone pairs?

Back 1408

square planar

Front 1409

Draw a bent molecule?

Back 1409

Front 1410

Draw a trigonal pyrmidal molecule?

Back 1410

Front 1411

Draw a T shape molecule?

Back 1411

Front 1412

Draw a see saw molecule?

Back 1412

Front 1413

Draw a square planar molecule

Back 1413

Front 1414

Draw a square pyramidal molecule?

Back 1414

Front 1415

Draw a square planar molecule?

Back 1415

Front 1416

When you have two double bonds... how many bonded pairs is this equal to?

Back 1416

Two

Front 1417

Describe the shape of CO2?

Back 1417

1. The 4 bonded pairs around the central carbon atom are two double bonds so there are two bodning regions
2. The two bonded regions repel as far apart as possible giving the molecule a linear shape

Front 1418

The greater the number of electron pairs.... (shapes... angles)

Back 1418

... the smaller the bond angles

Front 1419

Describe the covalent bond between atoms of different elements? (related to electronegativity)

Back 1419

1. The nuclear charges are different
2. The atoms may be different sizes
3. The shared pair of electrons may be closer to one atom than the other

Front 1420

What is electronegativity?

Back 1420

A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

Front 1421

On what scale is electronegativity measured?

Back 1421

On the Pauling scale

Front 1422

What does a large pauling value indicate?

Back 1422

That the atoms of the element are very electronegative

Front 1423

How does electronegativity increase in the periodic table (in what directions)?

Back 1423

Across and up the periodic table

Front 1424

Why does electronegativity increase across the periodic table?

Back 1424

Because the nuclear charge increases (the number of protons in the nucleus)
The atomic radius decreases

Front 1425

What is the most electronegative atom?


What is the value?

Back 1425

Fluroine


4.0

Front 1426

What happens when electronegatibity is large?

Back 1426

1. One bonded atom will have a much greater attraction for the shared pair than the other bonded atom.
2. The more electronegative atom will have gained control of the electrons and then bond will now be ionic rather than covalent

Front 1427

What is the electronegativity difference of a covalent bond?

Back 1427

0

Front 1428

What is the electronegativity difference of a polar covalent bond?

Back 1428

0 to 1.8

Front 1429

What is the electronegativity difference between an ionic bond?

Back 1429

Greater than 1.8

Front 1430

In a non polar bond describe the bonded electron pair?

Back 1430

The bonded electron pair is shared equally between the bonded atoms

Front 1431

When is a bond non polar?

Back 1431

1. The bonded atoms are the same
2. The bonded atoms have the same or similar electronegativity

Front 1432

What is a pure covalent bond?

Back 1432

Pure covalent bonds exist when there is no difference between the two atoms sharing the electrons. The electronegativity of the two atoms is identical.

Front 1433

Describe the electronegatiity of hydrocarbons?

Back 1433

Crabon and hydrogen atoms have a very similar electonegativities and form non polar bonds.

Front 1434

Describe hydrocarbon liquids and water?

Back 1434

They are non polar solvents and do not mix with water

Front 1435

Describe the bonded electron pair in a polar bond?

Back 1435

The bonded electron pair is shared unequally between the bonded atoms

Front 1436

What is a polar covalent bond?

Back 1436

When the bonded atoms and different and have different electronegativity values

Front 1437

Describe the bonding in HCl, hydrogen hads an electronegatiity of 2.1 and chlorine has an electrogegativity of 3.0?

Back 1437

1.The chlorine atom is more elctronegative than the hydrogen atom
2. The chlroine atom has a greater attraction for the bonded pair of electrons than the hydrogen atom, resulting in a polar covalent bond
3. The HCL bond is polarised with a small partial charge on the hydrogen atom and a small partial negative charge on the chlorine atom

Front 1438

What does 𝛿 stand for?


What does it mean?

Back 1438

It stands for delta


It means smalls

Front 1439

describe the difference between𝛿+, 𝛿– and + and –?

Back 1439

The two charges 𝛿+ and 𝛿– are partial chanrges and therefore are much smaller than the full charge

Front 1440

What is the seperation of opposite charges called?

Back 1440

A dipole

Front 1441

Describe the dipole in a polar covalent bond?

Back 1441

it does not change and is called permenent dipole

Front 1442

Is HCL polar or non polar?

Back 1442

It is polar

Front 1443

Describe the polarity of molecules with more than two atoms?

Back 1443

There may be two or more polar bonds. Depending on the shape of the molecule, the dipoles may reinforce one another to produce a larger dipole over the whole molecule, or cancel out the dipoles if they act in opposite directions

Front 1444

Describe the polarity of the H2O molecule?

Back 1444

1. The two O–H bonds each have different permanent dipoles
2. The two dipoles act in different directions but do not oppose each other
3. Overall the oxygen end of the molecule has a𝛿– charge and the hydrogen end of the molecule has a𝛿+ charge so it is polar

Front 1445

Describe the polarity of a CO2 molecule?

Back 1445

1. The two C––O bonds each have apermenant dipole
2. The two dipoles act in opposite directions and exactly oppose one another
3. The dipoles cancel and the overal dipole is 0 meaning it is non–polar

Front 1446

In an ionic bond being dissolved in water, what are the metal ions attracted to, and what are the non metal ions attarcted to?

Back 1446

The metal ions are positive and attracted to the oxygen of the water


The non metal ions are negative and attracted to the hydrogen of the water

Front 1447

What do covalent bonds do?

Back 1447

They holds the atoms in a molecule together

Front 1448

What are intermolecular forces?

Back 1448

They are weak interactions between dipoles of different molecules

Front 1449

What are the three categories that intermolecular forces fall into?

Back 1449

1. Induced dipole dipole interactions (London forces)
2. Permanent dipole dipole interactions
3. Hydrogen bonding

Front 1450

What are intermolecular forces responsible for?


What are covalent bonds responsible for?

Back 1450

The physical properties such as melting and boiling points


Determining the identity and chemcial reactions of molecules

Front 1451

What are the units of bond enthalpy?

Back 1451

KJmol^–1

Front 1452

What is the bond enthalpy of London forces?

Back 1452

1–10 KJmol^–1

Front 1453

What is the bond enthalpy of permanent dipole–dipole interactions?

Back 1453

3–25KJmol^–1

Front 1454

What is the bond enthalpy of hydrogen bonds?

Back 1454

10–40 KJmol^–1

Front 1455

What is the bond enthalpy of single covalent bonds?

Back 1455

150–500 KJmol^–1

Front 1456

What are london forces?

Back 1456

They are weak intermolecular forces that exist between all molecules, whether polar or non polar. The act between induced dipoles in different molecules

Front 1457

What is the difference between Intermolecular forces and intramolecular forces?

Back 1457

Intermolecular forces are forces of attraction between two or more molecules


Inbtramolecular forces are forces in a compound, such as covalent, ionic and metallic bonds

Front 1458

Describe the origin of induced dipoles?

Back 1458

1. Movement of electrons produces a changing dipole
2. At any instant an instant dipole will exist but its position is constantly shifting
3. The instant dipole induces a dipole o na neighbouring molecules
4. This induced dipole induces further dipoles on neighbouring molecules, which then attract one another

Front 1459

Describe the time period of induced dipoles?

Back 1459

They are temporary. In the next instant of time, the induced dipoles may disappear, only for it to take place again amongst other molecules

Front 1460

What is the effect of increasing the number of electrons of the strength of induced dipole dipole interactions?

Back 1460

1. The larger the instant and induced dipoles
2. The greater the induced dipole–dipole interactions
3. The stronger the attractive forces between the molcules

Front 1461

What is the electronegativity value that is large enough to allow different elements in a molcule to be polar?

Back 1461

0.5

Front 1462

Describe the difference between the boiling point of helium and argon? (dipoles)

Back 1462

Larger numbers of electrons in argon mean larger induced dipoles than in helium. This means that more energy is needed to overcome the intermolecular forces, so the boiling point of argon is greater than helium

Front 1463

What is it recommended that van der Waal's forces relate too?

Back 1463

Used to both permanent and induced dipole–dipole interactions

Front 1464

What is the correct term to use when describing dipole dipole interactions?


What else can be used to describe them?

Back 1464

London forces


Dispersion forces

Front 1465

What do permeanent dipole dipole interactions act between?

Back 1465

The permenant dipoles in different polar molecules

Front 1466

Describe why the boiling point of F–F is less than H–Cl?

Back 1466

1. Fluroine molecules are non polar and only have london forces between molecules
2. Hydrogen choride molecules are polar and have london forces and permanent dipole dipole interactions between molcules
3. Extra energy is required to break the additional permenant dipole dipole interactions between hydrigen chloride molecules
4. The boiling point of Hydrogen Chloride is therefore higher

Front 1467

What is a simple molecular substance made up of?

Back 1467

Simple molecules, containging a definite number of atoms with a definite molecular formula

Front 1468

What do simple molecules form in solid state?

Back 1468

A simple molecular lattice

Front 1469

Describe a simple molecular lattice?

Back 1469

1. The molecules are held in place by weak intermolecular forces
2. The atoms within each molecule are bonded together strongly by covalent bonds

Front 1470

What are the bonds in all simple molecular substances? (Type of bonds between atoms)

Back 1470

They are all covalently bonded

Front 1471

What can simple molecular susbstances exist as at room temperature?

Back 1471

Soilds, liquids or gases

Front 1472

Why do simple molecular susbstances have low melting and boiling points?

Back 1472

Because in a simple molecular lattice the weak intermolecular forces can be broken even by the energy present at low temperatures

Front 1473

What happnes when a simple molecular lattice is broken apart during melting?

Back 1473

1. Only ther weak intermolecular forces break
2. The covalent bonds are strong and do not break

Front 1474

What are the two categorise that covalent substances with simple molecular sturcture fall into?

Back 1474

Polar and non polar

Front 1475

Which type of simple molecular structure is it easiert to predict the solubility of?

Back 1475

Non polar substances

Front 1476

What causes a molecule to be polar?

Back 1476

When the ends of a molecule – called dipoles – carry an unequal distribution of charge

Front 1477

Describe atoms with a high electrongeativity?

Back 1477

An atom with a high electronegativity will tend to attract bonded electrons towards it.

Front 1478

Describe atoms with a low electronegativity?

Back 1478

An atom with a low electronegativity will have a very weak attraction for electrons.

Front 1479

Draw electronegativity in a periodic table?

Back 1479

Front 1480

Describe the trends in electronegativity values in the periodic table?

Back 1480

1. Increase from left to right across a period in the periodic table

2. Decrease on descending a group.

Front 1481

Why is fluroine the most electronegative element?

Back 1481

1. Fluorine is so close to ideal electron configuration, the electrons are held very tightly to the nucleus
2. It has the smallest atomic radius of the halogens.
3. Because the protons are closer to the outermost shell of Fluorine so the strength of the pull is higher towards the electrons

Front 1482

Describe the relationship between ionisation energy and electronegativity?

Back 1482

Atoms with greater electronegativities also have greater ionization energies

Front 1483

Why does charge across a period increase (left to right)?

Back 1483

Electronegativity increases across a period because the number of charges on the nucleus increases as the number of protons increases. That attracts the bonding pair of electrons more strongly.

Front 1484

What does the attraction a bonding pair of electrons feels for a nucleus depend upon? Three factors electronegativity is defined by

Back 1484

1. The number of protons in the nucleus as these are what attract electrons
2. The distance the outer shell is from the nucleus
3. The amount of shielding created by inner electrons

Front 1485

Why does electronegativity decrease down the group?

Back 1485

As you go down a group, electronegativity decreases because the bonding pair of electrons is increasingly distant from the attraction of the nucleus as the number of shells increase and the shielding of inner electrons increases

Front 1486

What happens when a non polar simple molecular substance is added to a non polar solvent?

Back 1486

1. Intermolecular forces form between the molecules and the solvent
2. The interactions weaken the intermolecular forces in the simple molecular lattice, causing it to break and the coumpound to dissolve

Front 1487

What happens when a non polar simple molecular substance is added to a polar solvent?

Back 1487

1. There is little interaction between the molecules in the lattice and the solvent molecules
2. The intermolecular bonding within the polar solvent is too strong to be broken

Front 1488

Describe the typical solubilities of simple molecular substances?

Back 1488

They tend to be insoluble in polar solvents as many are non polar

Front 1489

Why can polar covalent subsatances dissolve in polar solvents?

Back 1489

Because the polar solute molecules and the polar solvent molecules can attract each other

Front 1490

Name some common polar bonds, allowing solutes to dissolve in solvents?

Back 1490

O–H bonds
H–Cl bonds

Front 1491

What does the solubility of a polar solute in a polar solvent depend upon?

Back 1491

The strength of the dipole

Front 1492

What chains can molecules contain that make them non polar?

Back 1492

Carbon chains

Front 1493

Describe the solubility of a molecule if it contains both O–H bonds and H–C bonds?

Back 1493

They are soluble in both polar and non polar substances

Front 1494

What do the hydrophyllic ends of a biological molecule contain that makes them polar?

Back 1494

An electronegative atom such as oxygen as this can interact with the water

Front 1495

What do the hydrophobic ends of a biological molecule contain that makes them non polar?

Back 1495

They are comprised of a carbon chain

Front 1496

Describe simple molecular structures and conductibg electricity?

Back 1496

1. There are no mobile charged particles in simple molecular structures
2. With no charged particles that can move there is nothing to complete an electrical circuit
3. Therefore simple molecular structures are non conductors of electricity

Front 1497

What is an atomic orbital?

Back 1497

A region around the nucelus than can hold us to two electrons with opposite spins

Front 1498

What is a bond angle?

Back 1498

The angle between two bonds at an atom

Front 1499

What is a bonded pair?

Back 1499

A pair of electrons shared between two atoms of make a covalent bond

Front 1500

What is a coordinate bond?

Back 1500

A shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only, also called a dative covalent bond

Front 1501

Define a covalent bond?

Back 1501

The strong electrostatic attraction between a shared pair of electrons and the nuceli of the bonded atoms

Front 1502

What is a delocalised electron?

Back 1502

Electrons that are shared between more than two atoms

Front 1503

Define a dipole?

Back 1503

A separation in electrical charge so that one atom of a polar covalernt bond, or one end of a polar molecule has a small positive charge, and the other has a small negative charge

Front 1504

Define electron coniguration?

Back 1504

A shorthand representation that shows how electrons occupy sub shells in an atom

Front 1505

Define electronegativity?

Back 1505

A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

Front 1506

Define a giant covalent lattice?

Back 1506

A three dimensional sturcture of atoms, bonded together by strong covalent bonds

Front 1507

Define a giant ionic lattice?

Back 1507

A three dimensional sturcture of oppostiley charged ions, bonded together by strong ionic bonds

Front 1508

Define a giant metallic lattice?

Back 1508

A three dimensional sturcture ofpositive ions and delocalised electrons, bonded together by strong metalic bonds

Front 1509

Define a group?

Back 1509

A vertical column in the periodic table. Element is a group have similar chemical properties and their atoms have the same number of outer shell electrons

Front 1510

Define a hydrogen bond?

Back 1510

A strong dipole dipole attraction between an electron deficient hydrogen atom of –NH, –OH or HF on one molecule and a lone oaur of electrons o a highly electronegative atom containing N,O or F on a different molecule

Front 1511

Define an induced dipole–dipole interaction?

Back 1511

Attractive forces between induced dipoles in different molecules also called London forces

Front 1512

Define an intermolecular force?

Back 1512

An attractive force between molecules. Intermolecule forces can be London forces, permanent dipole dipole interaction or hydrogen bonding

Front 1513

Define an ion?

Back 1513

A positvely or negatively charged atom ir a (covalently bonded) group of atoms (a polyatomic ion), where the number of electrons is different from the number of protons

Front 1514

Define ionice bonding?

Back 1514

The electrostatic attraction between positivie and negative ions

Front 1515

Define isotopes?

Back 1515

Atoms of the same element with different numbers of neutrons and different masses

Front 1516

Defune a lone pair?

Back 1516

An outer shell pair of electrons that is not involved in chemcial bonding

Front 1517

Define the mass number?

Back 1517

The sum of the numberof protons and neutrons in the nucelus, also known as the nuceleon number

Front 1518

Define a metallic bond?

Back 1518

The electrostatic attraction betweren positive metal ions and delocalised electroms

Front 1519

What is the moblie phase?

Back 1519

The phase that moves in chromotography

Front 1520

Define a molecular ion?

Back 1520

The positive ion formed in mass spectromerty when a molecule loses an electron

Front 1521

Define a molecule?

Back 1521

The smallest part of a covalent compound that can exist while retaining its chemical identity, consisting of two or moe atoms covalently bonded together

Front 1522

Define non polar?

Back 1522

With no charge separation across a bond or in a molecule

Front 1523

Define Pualing electronegativity value?

Back 1523

A value assigned as a measure of the relative attraction of a bonded atoms for the pair of electrons in a covalent bond

Front 1524

Define a period?

Back 1524

A horizontal row of elements in the periodic table. Elements show trend in properties across a period

Front 1525

Define periodicity?

Back 1525

A repeating trend in properties of theelements across each period of the periodic table

Front 1526

Define a permanent dipole?

Back 1526

A small charge difference that does not change across a bond with a slightly positive and sightly negative partial charge on the bonded atoms: the result of the bonded atoms having different electronegativities

Front 1527

Define permanant dipole–dipole interaction?

Back 1527

An attractive force between permanent dipoiles in neighboring polar molecules

Front 1528

Define a polar (molecule)?

Back 1528

With delta + and delta – at different ends of the molecule

Front 1529

Define a polar covalent bond?

Back 1529

A bond with a permanent dipole, having delta + and delta – partical charges on the bonded atoms

Front 1530

Define a polar molecule?

Back 1530

A molecule with an overall dipole, having taken into account any dipoles across bonds and the shape of the molecule

Front 1531

Define a polyatomic ion?

Back 1531

An ion containing more than one atom

Front 1532

Define proton number?

Back 1532

The number of protons in the nucleus of an atom, also known as the atomic number

Front 1533

Define the retention time?

Back 1533

In gas chromotography, the time for a component to pass from the column inlet to the detector

Front 1534

Define a reversible reaction?

Back 1534

A reaction that takes place in both the forward and reverse directions

Front 1535

Define a shell?

Back 1535

A group of atomic orbitals with the same principle quantum number 'n' also known as the main energy level

Front 1536

Define the shielding effect?

Back 1536

The repulsion between electrons to different inner shells. Shielding reduces the net attractive force between the positive nucelus on the outer shell electrons

Front 1537

Define a simple molecular lattice?

Back 1537

A three dimensional structure of molecules, bonded together by weak intermolecular forces

Front 1538

Define the stationary phase?

Back 1538

The phase that does not move in chromotography

Front 1539

Define a sub–shell?

Back 1539

A group of orbitals of the same type within a shell

Front 1540

Define a transition element?

Back 1540

A d–block element which forms an ion with an incomplete d–sub shell

Front 1541

Describe the strength of hydrogen bonds relative to other intermolecular forces?

Back 1541

It is the strongest type of intermolecule attractions

Front 1542

What shows a hydrogen bond?

Back 1542

A dashed line

Front 1543

Why is ice less dense than the liquid water?

Back 1543

1. Hydrogen bonds hold water molecules apart in an open lattice sturcture
2. The water molecules in ice are further apart than in water
3. Solid ice is less dense than liquid water and so floats

Front 1544

What does ice form on the surface of water?


What does this do?

Back 1544

It forms an insultaing layer on water, preventing the water from freezing solid to preserve fish and Aqautic life

Front 1545

How many hydrogen bonds can each water molecule form?


Why?

Back 1545

They can form four hydrogen bonds


Because there are two lone pairs on the oxygen and two hydrogen atoms

Front 1546

What shape does water form?


What is the bond angle?

Back 1546

An open tetrahedral lattice full of holes.


180 degrees

Front 1547

What makes ice less dense that water?

Back 1547

The tetrahedral shape it forms has holes in the sturcture, making the density of ice less than water on freezing.
When melting, the ice lattaice collapses and the molecules move closer, so liquid water is denser than solid ice

Front 1548

Describe why water has a relatively high melting and boiling point in comparision to a substance with just London forces?

Back 1548

1. Hydrogen bonds are stronger than Lodon forces
2. A large quanitity of energy is needed to break the hydrogen bonds, so water has a much higher melting and boiling point than just london forces

Front 1549

Describe hydrogen bonds when water is heated?

Back 1549

When the ice lattice breaks, the rigid arrangement of hydrogen bonds in the ice is broken. Wehn water boils, the hydrogen bonds break compleelty

Front 1550

Describe the properties of water without hydrogen bonds?

Back 1550

1. Boiling point of –75 degrees
2. Exist as a gas at room temperature and pressure
3. Little liquid water in most places on Earth
4. Life wouldn't exisit as we know it

Front 1551

For ions placed in the mass sepctrometer with a +1 charge what is m/z equal to?

Back 1551

The relative isotopic mass

Front 1552

What is relative atomic mass? Definition

Back 1552

The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon–12

Front 1553

What does the weighted mean mass of an atom take into account?

Back 1553

1. The percentage abundance of each isotope
2. The relative isotopic mass of each isotope

Front 1554

Why is there a loss of a fraction of a mass of protons, neutrons and electrons?

Back 1554

Because of the strong nucelur forces holding them together

Front 1555

Define relative isotopic mass?

Back 1555

It is the mass of an isotope relative to 1/12th of the mass of an atom of carbon–12

Front 1556

State which two elements from the first twenty elements of the modern periodic table are not arranged in order of increasing atomic mass?

Back 1556

Potassium and Argon

Front 1557

Why is it uncessacary to refer to carbon as either diamond or graphite when ionised?

Back 1557

Diamond and graphite form gaseous atoms of carbonwhen they are ionised

Front 1558

Describe what is meant by the term ionic lattice in terms of the type and arrangement of particles present?

Back 1558

Repeating pattern of oppositely charged ions

Front 1559

Why, is CH2Cl2 polar if Cl is very electronegative?

Back 1559

The dipoles do not cancel out because the molecule is non–symmetrical

Front 1560

What forces are present in NH3?

Back 1560

Hydrogen bonding and london forces

Front 1561

Give to annomolus properties of ice?

Back 1561

1. Density
2. High melting point

Front 1562

Describe why ice has a high melting point?

Back 1562

Hydrogen bonds are relatively strong and more energy is needed to overcome hydrogen bonding

Front 1563

Describe what particles carry the charge in a molten metal?

Back 1563

Delocalised electrons NOT ions

Front 1564

Electrons in the outer shells of elements with a smaller radius experiance...

Back 1564

Greater nucelar attraction

Front 1565

State the element in Period 3 that has the highest melting point and explain why?

Back 1565

Silicon
Because it is a metalloid that forms a giant covalent lattice. These bonds need lots of energy to be broken and therefore has a higher melting and boiling point that the simple molecules and metals

Front 1566

Draw the trend in boiling points across group 3?

Back 1566

Front 1567

Describe what might cause the relative atomic mass of a sample be different to the relative atomic mass given in the periodic table?

Back 1567

There are other isotopes present or some isotopes absent meaning there is different abundances of isotopes in the sample giving it a different atomic mass

Front 1568

In a mass spectormter garph produced for magnesium containing 24^magnesium and 26^magnesium, there is a peak at 12, 24 and 26. Why is there a peak at 12?

Back 1568

Because 2+ ions have been formed of 24^magnesium

Front 1569

Describe the difference of the atomic radius of 124^Te compared to 130^Te?

Back 1569

It is the same because both isotopes have the same number of protons so the same nuclear charge and they also have the same number of electrons

Front 1570

Describe the difference of the atomic radius of 24^Mg and 26^Mg?

Back 1570

They have the same atomic radius because both isotopes have the same number of protons and therefore the same nuclear charge and they both have the same number of electrons

Front 1571

Describe how the gaseous atoms of rubidium are ionised in a mass spectrometer?

Back 1571

They are passed by an electron gun which fires high speed and energy electrons at the rubidium atoms, knocking off electrons

Front 1572

Describe the electrons that come out of an electron gun in a mass spectrometer?

Back 1572

They are high speed and energy

Front 1573

What is the name of the revlevant part of the mass epctrometer where the abundance of an isotope is determined?

Back 1573

Detector/ Detector plate

Front 1574

Describe how the abundance of an isotope in a sample of rubidium is determine after hitting the detection plate?

Back 1574

The ions produce a charge, the size of the electrical signal produced is an indicator of the relative abundance of that isotope

Front 1575

Althought phosphine molecules (PH3) contain hydrogen atoms, there is no hydrogen bonding between phosphine molecules. Suggest why?

Back 1575

Because the phosphorus and hydrogen do not have a great enough electronegativity difference as phosphorus is not as electronegative as Oxygen, nitrogen and fluroine

Front 1576

Describe why metals are malleable?

Back 1576

Because the layers of ions in them can slide over each other

Front 1577

Titanisum can be hammered into objects with different shapes that have similar strengths, suggest why these objects have similar strengths?

Back 1577

Because the strong metallic bonding is reformed and so there is the same bond strength

Front 1578

BCl3 can be reduced by using hydrogen to form pure boron and HCL. Apart from changing the reaction conditions, suggest one way a company producing pure boron could increase its profits from this reaction?

Back 1578

By selling the HCl

Front 1579

What is the mass number?

Back 1579

The number of protons and neutrons in the nucelus of an atom of an element

Front 1580

In a mass spectrometer, the relative abundance of each isotope is proportional to the current generated by that isotope at the detector, explain how the current is generated?

Back 1580

Electrons are transferred from the detector plate to the positively charged ion causing a current to flow

Front 1581

What type of structure is carbon found as?


What is it not?

Back 1581

A giant molecular structure


A giant covalent lattice

Front 1582

Suggest why the melting point of sodium iodide is lower than the nelting point of sodium bromide?

Back 1582

Because iodine has more electrons so a greater atomic radius, because it is biger it has less of an attraction to the sodium ion

Front 1583

What is a mol?

Back 1583

It is the amount of substance that contains as many aroms as there are carbon atoms in exactly 12g of carbon–12 isotope

Front 1584

Describe the influence the heaviness of atoms has on the amount of substance of mol?

Back 1584

The heavier the atoms the smaller the amount of substance to equal one mol

Front 1585

What is molar mass?

Back 1585

It is the mass of one mole of a substance. This is essentially the relative atomic mass or the molecular mass

Front 1586

What are the units of molar mass?

Back 1586

gmol–1

Front 1587

If the RAM of Na is 23.0 what is the molar mass?

Back 1587

23.0 gmol–1

Front 1588

If the RAM of CH4 is 16.0, what is the molar mass?

Back 1588

16.0 gmol–1

Front 1589

What if the mass of one mole of Carbon if it has an Ar of 12?

Back 1589

12g

Front 1590

What if the mass of two mole of Carbon if it has an Ar of 12?

Back 1590

24g

Front 1591

What if the mass of half a mole of Carbon if it has an Ar of 12?

Back 1591

6g

Front 1592

What is the equation involving mass, moles and moleclar mass?

Back 1592

mass = number of moles x molar mass

Front 1593

What is the symbol for mass?

Back 1593

m

Front 1594

What is the symbol for moles?

Back 1594

n

Front 1595

What is the symbol for molecular mass?

Back 1595

M

Front 1596

What significant figures are used in mole calcualtions?

Back 1596

3 significant figures

Front 1597

What is the name given to the number of atoms in 12g (1 mole) of carbon 12?


What is the symbol?

Back 1597

Avogadros constant


Na

Front 1598

What is the definition of the empirical formula?

Back 1598

It is the lowest whole number ratio if atoms of each element in a coumpoundq

Front 1599

What is the molecular formula?

Back 1599

A formula that shows the number and type of atoms of each element present in a molecule

Front 1600

What is the acronym for the empirical formula?

Back 1600

M – Mass
A – Ar
D – Divide (the above)
R – Work out whole number ratio

Front 1601

Describe the appearance of hydrated salts?

Back 1601

They are usually coloured crystals

Front 1602

What are many coloured crystals?

Back 1602

Hydrated salts

Front 1603

What is a hydrated salt?

Back 1603

Where water molecules are part of the salts crystalline structure

Front 1604

What is the water in the crystalline sturcture of salts also known as?

Back 1604

The water of crystalline

Front 1605

What happens when you heat a hydrated salt?

Back 1605

It becomes anhydrous (dehydrated)

Front 1606

What colour is copper sulfate?

Back 1606

Blue

Front 1607

What happens when a hydrated salt becomes anhydrous?


Describe the last stages of removing water?

Back 1607

The crystalline structure is lost and a white powder remains.


It is very difficult to remove the last traces of water

Front 1608

What is a stoichiometry of a reaction?

Back 1608

The balancing number of the equation gives the ratio of moles that react. It is this that is the stoichiometry of the reaction

Front 1609

What does the balancing number of an equation give?

Back 1609

The ratio of moles that react, this is called the stoichiometry

Front 1610

When does stoichiometry only apply?

Back 1610

When the equation is balanced

Front 1611

What do chemists use balanced equations to find?

Back 1611

1. The quantities of reactants required to prepare a required quantity or a product2. The quantities of products that should be formed from certain quantities of reactants

Front 1612

What is the maximum amount of product possible from a reaction called?

Back 1612

The theoretical yield

Front 1613

What does the theoretical yeild assume?

Back 1613

1. All the reactants are converted into products

Front 1614

Why is the theoretical yield difficult to achieve?

Back 1614

1. The reaction may not have gone to completion
2. Other reactions (side reactions) may have taken place alongside the main reactions
3. Purification of the product may result in some loss of the product

Front 1615

The amount of product obatined from a reaction is called the....

Back 1615

Actual yeild

Front 1616

Describe the relationship between the theoretical yeild and actual yeild.

Back 1616

The actual yeild is lower than the theoretical yeild

Front 1617

How do you express the actual yeild of the theoretical yeild?

Back 1617

By a percentage yeild, the amount in % of the threoretical yield that is actually achieved

Front 1618

What is the equation for the percentage yeild?

Back 1618

actual yeild/theoretical yeild x100

Front 1619

Describe how to calculate the percentage yeild (step by step)?

Back 1619

1. Calculate the amount in moles that reacts
2. Use the equation to find the theoretical yield
3. Calculate the actual yield in moles
4. Use the molar values to calculate the percentage yield through use of the equation

Front 1620

What is the limiting reagent?

Back 1620

When you use two reactants with one reactant in excess, the reactant not in excess will be completely used up first and stop the reaction – this is the limiting reagent

Front 1621

How do you work out the limiting reagent?

Back 1621

By working out the number of moles of each and comparing them to the equation

Front 1622

What must calcualtions with a reactants in excess be based upon?

Back 1622

The limiting reagent

Front 1623

Why must calcualtions be based upon the limiting reagent?

Back 1623

Because if equal amounts of substance are allowed to react that usually do in a 2:1 ratio, the amount that is usually doubled will be used by first and the '1' will only be half used

Front 1624

What is atom economy?

Back 1624

Atom economy of a chemical reaction is a measure of how well atoms have been utilised

Front 1625

Describe the properties of a reaction with a high atom economy?

Back 1625

1. Produce a large proportion of desired products and few unwanted products
2. Are important for sustainability as they make the best of natural resources

Front 1626

What is atom economy solely based upon?


What else does it assume?

Back 1626

The balanced chemical equation


It assumes a 100% yield

Front 1627

What is the eqaution for atom economy?

Back 1627

Atom econ = sum of molar masses of desired products / sum of molar masses of all products

Front 1628

What does improving atom economy do?

Back 1628

1. Makes individual processes more efficient
2. Preserves raw materials
3. Reduces waste

Front 1629

Describe the ideal chemical process for atom economy?

Back 1629

A use would be found for all products and the atom economy would be 100%

Front 1630

Where is carbon obtained from?

Back 1630

Coal

Front 1631

Where is hydrogen obtained from?

Back 1631

Steam from water

Front 1632

Describe what parts atom economy dosen't shead light on?

Back 1632

1. It dosen't explain the costs for the initial starting materials
2. It doesn't factor in how readily available the reactants are
3. Reactants may have a larger atom economy but poor percentage yield and efficiency depends on both factors

Front 1633

Why don't we use masses to measure gasses?


What do we use instead?

Back 1633

Because it is to difficult to measure the mass of a gas


Gas Volumes

Front 1634

What is Avogadros law?

Back 1634

Equal volumes of all gasses measured at the same temperature and same pressure will contain the same number of molecules

Front 1635

What is the symbol for molar volume?

Back 1635

Vm

Front 1636

What is the molar volume?

Back 1636

What volume of gas contains 6.022 x 10^23 particles

Front 1637

What space does 1 mole of gas occupy at room temperature and pressume?

Back 1637

24.0 dm^3 or 24000 cm^3

Front 1638

What is the formula for the calculation involing volume and molar volume?

Back 1638

moles = volume/molar molume

Front 1639

What is the room temperature used in Avogados law?


What is the pressure used?

Back 1639

25 degrees celcius


1 atm (atmosphere)

Front 1640

What is the ideal gas equation used for?

Back 1640

Gasses at different temperatures and pressure

Front 1641

What is the ideal gas euation?

Back 1641

PV=nRT

Front 1642

What does P stand for in the ideal gas equation?


What are its units?

Back 1642

Pressure


Pa

Front 1643

What does V stand for in the ideal gas equation?


What are its units?

Back 1643

Volume


m^3

Front 1644

What does the n stand for in the ideal gas equation?


What are its units?

Back 1644

Amount of gas


Moles

Front 1645

What does R stand for in the ideal gas equation?


What are its units?


What is its value?

Back 1645

Ideal constant


Jmol^–1 K^–1


3.31

Front 1646

What value of kilo pascals is equal to 1atm?


What value of pascals is equal to 1 atm?

Back 1646

101 KPa


101 x 10^3 Pa

Front 1647

What volume in m^3 is equal to 1 cm^3?


What volume in m^3 is equal to 1 dm^3

Back 1647

1 x 10^–6 m^3


1 x 10^–3 m^3

Front 1648

What does T stand for in the ideal gas equation?


What are its units?

Back 1648

Temperarture


K (kelvin)

Front 1649

What are the assumptions the ideal gas equation is based upon?

Back 1649

1. The particles have a random motion
2. The particles have no elastic collisions so energy is conserved
3. The particles have a negligible size
4. The particles have no intermolecular forces

Front 1650

How are substances made into solutions?

Back 1650

By dissolving a solute into a solvent

Front 1651

What does concentration measure?

Back 1651

The amount of solute in moles per dm^3 of solution

Front 1652

What unit does concenration have?

Back 1652

mol dm^–3

Front 1653

What is the formula involing concentration, moles and volume?

Back 1653

Concentration = moles/volume

Front 1654

What is 1 cm^3 equal to in ml?

Back 1654

1ml

Front 1655

What is 1000 cm^3 equal to in dm^3 ?


What is 1000 cm^3 equal to in liters?

Back 1655

1 dm^3


I litre

Front 1656

What is 1 dm^3 equal to in liters?


What is 1 dm^3 equal to in ml?

Back 1656

1 litre


1000 ml

Front 1657

What is the formula of an ammonium atom?


What is its charge?

Back 1657

NH4


+1

Front 1658

What is the formula of an hydroxide ion?


What is its charge?

Back 1658

OH


–1

Front 1659

What is the formula of a nitrate ion?


What is its charge?

Back 1659

NO3


1–

Front 1660

What is the formula of a carbonate ion?




What is its charge?

Back 1660

CO3


2–

Front 1661

What is the formula of a sulphate ion?


What is its charge?

Back 1661

SO4


2–

Front 1662

What is the formula of a sulphite ion?


What is its charge?

Back 1662

SO3


2–

Front 1663

What is the formula ofa phosphate ion?


What is its charge?

Back 1663

PO4


3–

Front 1664

How can you work out water of cyrstallisation?

Back 1664

Using MADR (same as the empirical formula) but making sure the metal is always to the ratio of 1

Front 1665

What does monatomic mean?

Back 1665

It consisits of 1 atom

Front 1666

Name 5 monatomic elements?

Back 1666

1. Helium
2. Neon
3. Argon
4. Krypton
5. Radon

Front 1667

Name three giant colvalent elements?

Back 1667

1. Diamond
2. Graphite
3. Silicon

Front 1668

Name one giant covalent compound?

Back 1668

Silicon dioxide

Front 1669

Define the term simple molecular?

Back 1669

These contain only a few atoms held together by strong covalent bonds.

Front 1670

What are diatomic molecules?

Back 1670

Consisting of two atoms

Front 1671

Name 7 diatomic elemental gasses?

Back 1671

1. Hydrogen
2. Nitrogen
3. Oxygen
4. Fluorine
5. Chloride
6. Bromine
7. Iodine

Front 1672

Name nine simple molecular elements?

Back 1672

1. Hydrogen2. Nitrogen
3. Oxygen
4. Fluorine
5. Chloride
6. Bromine
7. Iodine
8. Phosphorus
9. Sulfur

Front 1673

Name 7 simple molecular compounds?

Back 1673

1. Carbon dioxide
2. Carbon monoxide
3. Nitrogen monoxide
4. Nitrogen dioxide
5. Sulfur dioxide
6. Sulfur trioxide
7. ammonia

Front 1674

What is the formula of a hydrogen carbonate ion?

What is its charge?

Back 1674

HCO3


1–

Front 1675

What is the formula for sulfuric acid?

Back 1675

H2SO4

Front 1676

What is the formula of hydrochloric acid?

Back 1676

HCl

Front 1677

What is the formula of nitric acid?

Back 1677

HNO3

Front 1678

What is the formula of phosphoric acid?

Back 1678

H3PO4

Front 1679

What is silicon dioxide also known as?


What is its formula?

Back 1679

Silica


SiO2

Front 1680

What is the formula of a sulfide ion?

What is its charge?

Back 1680

S


2–

Front 1681

What is a hydride?

Back 1681

A binary (two parts) compound of hydrogen with a metal.

Front 1682

What is the forumla of silver?


What is the amount of electrons given by silver?

Back 1682

Ag


+1

Front 1683

What happens when you react a substance + oxygen?

Back 1683

You form oxides

Front 1684

What happens when you react metal and water?

Back 1684

You form a metal hydroxide + hydrogen

Front 1685

What do you form when you react a metal +acid?

Back 1685

Salt + hydrogen

Front 1686

What do you form when you react a metal oxide and acid?

Back 1686

Salt+ water

Front 1687

What do you form when you react a hydroxide and acid?

Back 1687

Salt + water

Front 1688

What do you form when you react a carbonate +acid?

Back 1688

Salt + water + carbon dioxide

Front 1689

What do you get when you react a hydrogencarbonate and acid?

Back 1689

Salt + water + carbon dioxide

Front 1690

What do you get when you react ammonia and acid?

Back 1690

Ammonium salt

Front 1691

What do you get when you thermally decompose a metal carbonate?

Back 1691

Metal oxide + carbon dioxide

Front 1692

What is the formula of an ammonium ion?


What is its charge?

Back 1692

NH4


+1

Front 1693

What is the formula of ammonia?

Back 1693

NH3

Front 1694

What is the oxidation number?


What is it often called?

Back 1694

The oxidation state, often called the oxidation number, is an indicator of the degree of oxidation(loss of electrons) of an atom in a chemical compound.

Front 1695

What is the oxidation number of elements?

Back 1695

It is always 0

Front 1696

What is a pure element?

Back 1696

A pure element is a substance consisting of only one isotope of a single element.

Front 1697

What is the oxidation number of H2, O2, Na and Fe?

Back 1697

They are all pure elements so 0

Front 1698

Where is the sign of an oxidation number placed?

Back 1698

Before the number

Front 1699

What is the oxidation number of Oxygen as a combined element?

Back 1699

–2

Front 1700

What is the oxidation number of hydrogen as a combined element?

Back 1700

+1

Front 1701

What is the oxidation number of Fluroine as a combined element?

Back 1701

–1

Front 1702

What is the oxidation number of an ion such as Na+ or K+ as combined elements?

Back 1702

+1

Front 1703

What is the oxidation numbers of an ion such as Mg2+ ad Ca2+ as combined elements?

Back 1703

+2

Front 1704

What is the oxidation number of ions such as Cl– or Br– as combined element?

Back 1704

–1

Front 1705

What are the special cases charges of oxidation numbers?

Back 1705

1. Hydrogen in metal hydrides
2. Oxygen in peroxides
3. Oxygen bonded to Fluroine

Front 1706

What is the charge on hydrogen in a metal hydrides

Back 1706

–1

Front 1707

What is the charge of Oxygen in a peroxide?

Back 1707

–1

Front 1708

What is the charge on Oxygen bonded to Flurione?

Back 1708

+2

Front 1709

What is the rule for oxidation numbers in combined atoms?

Back 1709

The sum of the oxidation numbers must equal the total charge

Front 1710

What do Roman numerals in naming show?

Back 1710

The oxidation state of an element without a sign

Front 1711

What does iron(II) show?


What does Iron(III) show?

Back 1711

It is Fe2+ with oxidation number +2


It is Fe3+ with oxidation number +2

Front 1712

Name some common peroxides?

Back 1712

Na2O2
H2O2
BaO2
CH3COOOH

Front 1713

How does oxidation effect oxidation states?

Back 1713

Oxidation involves an increase in oxidation state

Front 1714

How does reduction effect oxidation states?

Back 1714

Reduction involves a decrease in oxidation state

Front 1715

What is the oxidation state of Chlorine?

Back 1715

–1

Front 1716

Why does the oxidation state of oxygen change when combined with flurione?

Back 1716

Because flurione is the most electronegative element

Front 1717

Describe the actucal oxidation state of chlorine?

Back 1717

There are so many different oxidation states that chlorine can have in these, that it is safer to simply remember that the chlorine doesn't have an oxidation state of –1 in them, and work out its actual oxidation state when you need it.

Front 1718

What is the oxidation state of chromium in Cr2+?

Back 1718

+2

Front 1719

What is the oxidation state of chromium in CrCl3?

Back 1719

+3

Front 1720

What is the oxidation state of chromium in the dichromate ion, Cr2O72–?

Back 1720

+6

Front 1721

What is the oxidation state of copper in CuSO4?

Back 1721

+2

Front 1722

What is the modern name of the No2– ion (nitrite)?
What is the oxidation number of the nitrogen?

Back 1722

Nitrate(III)
+3

Front 1723

What is the modern name of the NO3– ion(nitrate)?


What is the oxidation number of the oxygen?

Back 1723

Nitrate(V)


+5

Front 1724

What is OILRIG?

Back 1724

Oxidation is loss


Reduction is gain

Front 1725

What were the terms oxidation and reduction originally applied to?

Back 1725

Reactions invloving oxygen where:
1. Oxidation is the addition of oxygen
2. Reduction is the removal of oxygen

Front 1726

Describe oxidation/reduction in this reaction in terms of oxygen:


CuO(s) + H2(g) ––> Cu(s) +H2O(l)

Back 1726

The Copper (II) has been reduced as it has lost oxygen


The Hydrogen has been oxidised as it has gained oxygen

Front 1727

What are redox reactions?

Back 1727

They are reactions which involve both reduction and oxidation. If one happens, so must the other – if something is reduced, something must be oxidised

Front 1728

Describe redox in terms of electrons?

Back 1728

Reduction is the gain of electrons


Oxidation is the loss of electrons

Front 1729

Describe redox in terms of electrons in this reaction:


2Fe(s)+3Cl2(g) ––> 2FeCl3(s)

Back 1729

FeCl3 contains positive and negative ions Fe^3+ and Cl^–


Iron loses electrons and is oxidised 2Fe–––> 2Fe^3+ 6e^–


Chlorine gains electrons and is reduced 3Cl2 + 6e^– ––> 6Cl^–

Front 1730

Describe redox in terms of oxidation number?

Back 1730

Reduction is a decrease in oxidation number


Oxidation is an increase in oxidation number

Front 1731

If Cu reacts to form a compound with an oxidation state of +2 what has it been.....

Back 1731

It have lost electrons and so has been oxidised

Front 1732

If Ag reacts to form an oxidation state of +1 what has it been.....

Back 1732

It has lost electrons and therefore oxidised

Front 1733

What do all acids contain in their formulae?

Back 1733

Hyrogen

Front 1734

What happens when an acid is dissolved in water?

Back 1734

The acid releases H+ ions as protons into the water

Front 1735

What is a strong acid?

Back 1735

An acid that releases all of its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solution

Front 1736

What does dissociates mean?

Back 1736

Split into separate smaller atoms, ions, or molecules

Front 1737

Given an example of a strong acid?


Give an example of a weak acid?

Back 1737

HCl – hydrochloric acid


CH3COOH – ethanoic acid

Front 1738

What is a weak acid?

Back 1738

An acid that only releases a proportion of its avalibale hydrogen atoms into solution as H+ ions. It partially dissociates in aqueous solution

Front 1739

What does an equilibirium sign in a reaction dissolving an acid in an aqueous solution mean?

Back 1739

That the forward reaction is not complete

Front 1740

What does a base do when it reacts with an acid?

Back 1740

The base neutralises the acid to form a salt

Front 1741

What are classified as bases?

Back 1741

Metal oxides, metal hydroxides, metal carbonates and ammonia

Front 1742

What is an alkali?

Back 1742

It is a base that dissolves in water, releasing hydroxide ions (OH^–) into the solution

Front 1743

Define a base?

Back 1743

A substance capable of reacting with an acid to form a salt and water, or of accepting or neutralizing hydrogen ions.

Front 1744

What is produced in neutralisation of an acid?

Back 1744

H+ ions react with a base to form a salt and neutral water

Front 1745

What is the type of salt formed from hydrochloric acid?

Back 1745

Chloride

Front 1746

What is the type of salt formed from Sulfuirc acid?

Back 1746

Sulfate

Front 1747

What is the type of salt formed from nitric acid?

Back 1747

Nitrate

Front 1748

What is the type of salt formed from ethanoic acid?

Back 1748

Ethanoate

Front 1749

What is the type of salt prodcued from phosphoric acid?

Back 1749

Phosphate

Front 1750

What is the type of salt produced from methanoic acid?

Back 1750

Methanoate

Front 1751

What is a titration?

Back 1751

It is a technique used to accuratley measure the volume of one solution that reacts exactly with another solution

Front 1752

What can titrations be used for?

Back 1752

1. Finding the concentration of a solution
2. Identifying unknown chemicals
3. Finding the purity of a substance

Front 1753

What is checking purity of a substance important for?

Back 1753

1. Quality control
2. Especially for those for human use such as medicines, food and cosmetics
3. A tiny amount of impurity could cause a great deal of harm to a patient

Front 1754

What is a standard solution?

Back 1754

It is a solution of a known conentration

Front 1755

What flasks are used to make up a standard solution?

Back 1755

A Volumetric flask`

Front 1756

What are the typical sizes of volumetric flasks?

Back 1756

100 cm^3


250 cm^3

Front 1757

How do you prepare a standard solution?

Back 1757

1. The solid is first weighed accurtely
2. The solid is dissolved in a beaker using less distilled water than needed to fill the volumetric flask
3. The solution is transferred to a volumeric flask, the last traces of solution are rinsed in with distilled water
4. The flash is filled to the graduation line by adding distilled water dropwise untill the bottom of the meniscus lines up with the mark
5. The volumetric flask is slowly inverted to mix the solution

Front 1758

What is the line on a volumetric flask called?

Back 1758

The graduation line

Front 1759

Why do you have to be careful when filling a volumetric flask to the meniscus line?

Back 1759

Because if too much water is added, the solution will be too dilute and be prepared again

Front 1760

Why would results be inconsistent if the volumetric flask is not inverted during preparing a standard solution?

Back 1760

Because the solution needs to be mixed

Front 1761

What tolerances are a pipette and a burette measured to?

Back 1761

10cm^3


25cm^3


50 cm^3

Front 1762

What is a burette reading read to?

Back 1762

The nearest half divison with the bottom of the meniscus on a mark or between two marks. the reading always has two decimal places, the last either being a 0 or 5

Front 1763

What is the acid–base titration procedure?

Back 1763

1. Add measured volume of one solution to a conical flask using a pippette
2. Add the other solution to a burette and record the initial burette reading
3. Add a few drops of indicator to the solution in the conical flask
4. Run the solution in the burette into the solution in the conical flask, swirling it throughout to mix the two solutions
5. The indicator changes colour showing the end point of the titration.
6. Record the final burette reading
7. A quick trial tire is carried out to find the approximate tire
8. the titration is repeated accuratley, adding the solution drops wise
9. Further titrations are carried out untill two valuyes are concordant

Front 1764

What does the end point of a titration indicate?

Back 1764

The volume of one solution that exactly reacts with the volume of the second solution

Front 1765

Why is the second ionisation enthalpy important when explaining group 2 reactivity?

Back 1765

Group 2 elements react by losing two electrons to form 2^+ ions

Front 1766

What is the molecular formula of benzene?

Back 1766

C6H6

Front 1767

Describe (generally) the properties of benzene and its uses?

Back 1767

1. It is colourless
2. Sweet smelling
3. Highly flammable liquid
4. Found in crude oil and petrol
5. Found in cigarette smoke
6. Is carcinogenic

Front 1768

What type of hydrocarbon is benzene classified as?

Back 1768

Aromatic or arene

Front 1769

Name the two different models of benzene?

Back 1769

1. The Kekule model
2. The delocalised model

Front 1770

Historically, what was the term aromatic used to classify?


Today, what is this term also used to classify?

Back 1770

The derivatives of benzene as many pleasant smelling compounds contained a benzene ring


Many odourless compounds that contain a benzene ring are also described as aromatic

Front 1771

What does the kekule model say (text) is the structure of benzene?

Back 1771

Six membered ring of carbon atoms joined by alternate single and double bonds

Front 1772

Draw the kekule model of benzene? Draw the skeletal and displayed structures

Back 1772

Front 1773

What are the three pieces of evidence that disprove the kekule model of benzene?

Back 1773

1. The lack of reactivity of benzene
2. The lengths of the carbon–carbon bonds
3. Hydrogenation enthalpies

Front 1774

Describe how the lack of reactivity of benzene disproves the kekule model?

Back 1774

1. Benzene does not undergo electrophilic addition reactions
2. Benzene does not decolourise bromine under normal conditions


This shows that it cannot have any C=C bonds

Front 1775

Describe how the lengths of the carbon–carbon bonds in benzene disproves the kekule model?

Back 1775

All the bonds in benzene are 0.139 nm in length which is between that of a single bond and a double bond

Front 1776

Using what technique is it possible to determine the length of the bonds in compounds?

Back 1776

X–ray diffraction

Front 1777

What is the length of a single bond?

Back 1777

0.153nm

Front 1778

What is the length of a double bond?

Back 1778

0.134nm

Front 1779

What is the length of a bond in benzene?

Back 1779

0.139nm

Front 1780

Describe how the hydrogenation enthalpies of benzene disproves the kekule model?

Back 1780

1. If benzene had tis structure it would be expected to have an enthalpy change of hydrogenation that is three times that of cyclohexene
2. The actual enthalpy change of benzene is less, so benzene is more stable than expected

Front 1781

Draw the hydrogenation of cyclohexene and give its value.

Back 1781

Front 1782

What is the expected enthalpy of hydrogenation of benzene?


What is the actual?

Back 1782

–360 KJ mol^–1


–208 KJ mol^–1

Front 1783

Draw the delocalised structure of benzene?

Back 1783

Front 1784

What are the main features of the delocalised model of benzene?

Back 1784

1. Benzene is planar
2. Each carbon has two bonds to other carbons and one to a hydrogen atom
3. Each carbon has one electron in a p–orbital at right angles of the plane of the bonded carbon
4. Adjacent p–orbitals overlap sideways in both directions
5. The overlapping creates a system of pi–bonds
6. The electrons are said to be delocalised

Front 1785

What is a substituent group?

Back 1785

An atom or group of atoms taking the place of another atom or group or occupying a specified position in a molecule.

Front 1786

Name this compound?

Back 1786

Ethylbenzene

Front 1787

Name this compound?

Back 1787

Chlorobenzene

Front 1788

Name this compound?

Back 1788

Nitrobenzene

Front 1789

When is benzene considered to be the substituent group?

Back 1789

1. When attached to an alkyl chain with a functional group
2. When attached to a carbon chain with seven or more carbon atoms

Front 1790

What is the prefix used when benzene is the substituent group?

Back 1790

phenyl

Front 1791

What are the three exceptions to the rules of benzene as a substituent group?

Back 1791

1. Benzoic acid
2. Phenylamine
3. Benzaldehyde

Front 1792

What are the reactants and conditions for nitrification of benzene?

Back 1792

Nitric acid (HNO3)
Sulphuric acid as the catalyst (H2SO4)
Heated to 50 degrees using a water bath to maintain a steady temperature

Front 1793

Draw the overall equation for the nitration of benzene? (Not mechanism)

Back 1793

Front 1794

Why is the temperature maintained at 50 degrees and not let to go higher in the nitration of benzene?

Back 1794

Because further substitution may occur, leading to the production of dinitrobenzene

Front 1795

Why is nitrobenzene important?

Back 1795

It is a starting material in the preparation of:
1. Dyes
2. Pharmaceuticals
3. Pesticides
4. Paracetamol

Front 1796

What is the name of the mechanism for the nitration of benzene?

Back 1796

Electrophilic substitution

Front 1797

What is the electrophile in the nitrification of benzene?


How is this generated (brief)?

Back 1797

The No2 ^+ ion


It is produced through the reaction of concentrated nitric acid and concentrated sulphuric acid

Front 1798

Why, once a bond has been made to the NO2 ion in the nitrification of benzene is it unstable?


What type of bond is it?

Back 1798

Because it has formed a dative covalent bond

Front 1799

What is the equation for the generation of the NO2^+ ion in the nitrification of benzene?

Back 1799

HNO3 + H2SO4 ––> NO2^+ + HSO4^– + H2O

Front 1800

When do halogens react with benzene?

Back 1800

Only in he presence of a halogen carrier

Front 1801

Give common halogen carriers? (four)

Back 1801

1. AlCl3
2. FeCl3
3. AlBr3
4. FeBr3

Front 1802

What does in situ mean?

Back 1802

In the reaction vessel

Front 1803

When are halogen carriers generated?

Back 1803

In situ, from the metal and the halogen

Front 1804

Under what conditions does bromine react with benzene?

Back 1804

At room temperature and pressure
In the presence of a halogen carrier
Bromine must be present

Front 1805

By which mechanism does the halogenation of benzene occur?

Back 1805

Electrophilic substitution

Front 1806

Draw the equation for the preparation of bromobenzene (not mechanism)?

Back 1806

Front 1807

Why does benzene not react with bromine (which is a halogen carrier catalyst required)?

Back 1807

Because benzene is too stable to react with non–polar bromine. Therefore the electrophile Br^+ has to be generated

Front 1808

How is Br^+ generated in the bromination of benzene?

Back 1808

Bromine react with the halogen carrier catalyst for example FeBr3:


Br2 + FeBr3 ––> FeBr4^– + Br^+

Front 1809

What is this ion called: Br^+?

Back 1809

A bromonium ion

Front 1810

Draw the mechanism for the formation of bromobenzene from benzene and a bromonium ion?
Include the catalyst

Back 1810

Front 1811

What is the final stage of the bromination of benzene?

Back 1811

The H^+ ion produced reacts with the halogen carrier catalyst:


H^+ + FeBr4^– ––> FeBr3 + HBr

Front 1812

Draw the mechanism for the chlorination of benzene?

Back 1812

Front 1813

What is an alkylation reaction?

Back 1813

It is the substitution of a hydrogen atom in the benzene ring by an alkyl group.

Front 1814

What do you need to carry out an alkylation reaction of benzene (non–specific)?

Back 1814

Benzene
Haloalkane
AlCl3 (halogen carrier catalyst)

Front 1815

Why is AlCl3 needed in alkylation reactions of benzene?

Back 1815

Because benzene does not have a great enough density to polarise Br2 so you need a halogen carrier catalyst to do this

Front 1816

What does alkylation change about a compound?

Back 1816

It increases the number of carbon atoms by forming carbon–carbon bonds

Front 1817

Who first carried out an alkylation reaction?


Therefore what name is sometimes given to the reaction?

Back 1817

Friedel and Crafts


Friedel–Crafts alkylation

Front 1818

Show an alkylation reaction to produce ethylbenzene?

Back 1818

Front 1819

What is an acylation reaction of benzene?
What is prouduced?

Back 1819

In which an acyl group is added to the benzene ring to form an aromatic ketone

Front 1820

What type of reaction (in terms of the type of mechanism0 is an acylation reaction?

Back 1820

Electrophilic substitution

Front 1821

What type of bonds do acylation reactions form?

Back 1821

carbon–carbon bonds

Front 1822

What is the first member of the acyl chloride homologous series/

Back 1822

Ethanoyl chloride


CH3COCl

Front 1823

Draw ethanoyl chloride?

Back 1823

Front 1824

What is an acyl chloride? (describe its derivative)

Back 1824

It is a carboxylic acid where the OH has been replaced by a chloride ion

Front 1825

What are localised electrons?


What are delocalised electrons?

Back 1825

Localised electrons are bonded electrons that are not free to move


Delocalized electrons are electrons in a molecule, ion or solid metal that are not associated with a single atom or a covalent bond.

Front 1826

What type of electrons are the electrons found in a pi–bond?

Back 1826

They are localised electrons found above and below the plane of the carbon atoms in the double bond

Front 1827

Describe the process of and so how alkenes can react with bromine?

Back 1827

1. The localised electrons in the pi–bond induce a dipole in the bromine molecule
2. The slightly positive bromine atom enables the bromine molecule to act like an electrophile

Front 1828

Why can benzene not react with non–polar bromine without a halogen carrier catalyst? (talk in terms of electrons in comparinson with an alkene)

Back 1828

1. Benzene is too stable to react with a non-polar bromine molecuole

2. Alkenes have high regions of electron density as localised electrons are found around double bonds

3. This has strong enough electron density to polarise the Br2 molecule and so react with it without a halogen carrier catalyst

Front 1829

Define adsorption?

Back 1829

The process that occurs when a gas or liquid is held to the surface of a solid

Front 1830

Define dehydration?

Back 1830

An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule

Front 1831

Describe the difference in electron density around any two carbon atoms in a benzene ring and the C=C double bond in an alkene?

Back 1831

The electron density in benzene is less than in the alkene

Front 1832

By which mechanism do alkenes react with bromine?
By which mechanism does benzene react with bromine?

Back 1832

Electrophilic addition
Electrophilic substitution

Front 1833

Define phenols?

Back 1833

They are a type of organic chemic containing a hydroxyl functional group bonded to an aromatic ring

Front 1834

What is the simplest member of the phenols?
Draw it
What is the molecular formula?

Back 1834

Phenol


C6H5OH

Front 1835

What are the chemical properties of phenol the same as?

Back 1835

They are simmilar to that if any chemical with an OH– group attached to the benzene ring

Front 1836

When is a conpound an alcohol rather than phenol?

Back 1836

When the OH– group is bonded to a carbon side chain rather than the aromatic ring

Front 1837

Describe the differences and simmillarities between the chemical properties of alcohols and phenols?

Back 1837

Simmilarities: they have some common reactions
Differences: many reactions are different as the proximity of the delocalised ring influences the –OH group

Front 1838

Name this chemical?

Back 1838

Phenol

Front 1839

Name this chemical?

Back 1839

2–hydroxybenzoic acid

Front 1840

Name this chemical?

Back 1840

2–nitrophenol

Front 1841

Name this chemical?

Back 1841

2–phenylethanol

Front 1842

How was phenol originally manufactured? Give the equation?

Back 1842

Using benzene, sulfuic acid and sodium hydroxide

C6H6 + H2SO4 + 2NaOH ––> C6H5OH + Na2SO3 + 2H2O

Front 1843

How is phenol manufactured nowdays? Give the equation?

Back 1843

From benzene and propene
C6H6 + C3H6 + O2 ––> C6H5OH + CH3COCH3

Front 1844

Other than the current method of using benzene and propene, which method of developing phenol are researchers currently investiagting? Give the equation

Back 1844

Using benzene and nitrogen oxide N2O
C6H6 + N2O ––> C6H5OH + N2

Front 1845

Describe phenols solubility in water compared to alcohols and why?

Back 1845

It is less soluble in water due to the presence or the non–polar benzene ring

Front 1846

What happens when phenol is dissolved in water?

Back 1846

It dissociates froning the phenoxide ion and a proton

Front 1847

Why is phenol a weak acid?

Back 1847

Because it has a low ability to dissociate to produce protons and a phenoxide ion

Front 1848

What type of acids are phenols?

Back 1848

They are weak acids

Front 1849

Describe the acidity of phenol in comparison to alcohols and carboxylic acids?

Back 1849

Phenol is more acidic than alcohols but less acidic than carboxylic acids
Alcohol < phenol < carboxylic acids

Front 1850

How can you compare the acidity of alcohols, phenols and carboxylic acids?

Back 1850

By comparing the acid dissociation constant Ka of them

Front 1851

Define the acid dissociation constant Ka?

Back 1851

The equilibrium constant that shows the extent of dissociation of a weak acid

Front 1852

Give one reaction of ethanol that shows it is less acidic than phenol?

Back 1852

Ethanol does not react with sodium hydroxide (a strong base) or sodium carbonate (a weak base)

Front 1853

What do phenols and carboxylic acids react with to show that they are more acidic than alcohols?

Back 1853

They both react with strong bases such as aqueous sodium hydroxide

Front 1854

Describe a reaction of carboxylic acids that show that theyvare more acidic than phenols?

Back 1854

Carboxylic acids, unlike phenols, are strong enough acids to react with the weak base sodium carbonate

Front 1855

Give the word equation of the reaction between phenol and sodium hydroxide (strong base)?

Back 1855

Phenol + sodium hydroxide ––> sodium phenoxide + water

Front 1856

Draw the image equation of the reaction between phenol and sodium hydroxide?

Back 1856

Front 1857

Draw the partial dissociation of phenol in water?

Back 1857

Front 1858

Describe generally the difference between the conditions of the reactions of phenol compared to benzene in electrophilic substitution reactions?

Back 1858

The reactions of phenol take place under milder conditions and more readily than the reactions of benzene

Front 1859

What happens when phenol reacts with benzene in terms of observation?

Back 1859

A white precipitate of 2,4,6–tribromophenol and decolourises the bronine water fron organe to colourless

Front 1860

What is the product of the reaction between phenol and bromine?

Back 1860

2,4,6–tribromophenol

Front 1861

Describe the conditions used in the reaction of phenol and bromine?

Back 1861

A halogen carrier catalyst is not required and the reaction is carried out at room temperature

Front 1862

Draw the reaction of phenol with bromine?

Back 1862

Front 1863

What is formed when phenol reacts with nitric acid?

Back 1863

A mixture of 2–nitrophenol and 4–nitrophenol is formed

Front 1864

Describe the conditions of the reaction between phenol and nitric acid?

Back 1864

Dilute nitrix acid at room temperature

Front 1865

Draw the reaction between phenol and nitric acid?

Back 1865

Front 1866

Describe the reactivity of phenol and benzene with bromine and nitric acid?
Describe why this is?

Back 1866

They react more readily with phenol, phenol reacts with dilute acid rather than concentrated like benzene
Phenol has increased activity caused by a lone pair of electrons from the oxygeb p orbital of the –OH group being donated into the pi–system, thus increasing the electron density of the ring which attracts electeophiles more strongly than benzene

Front 1867

Why is no halogen carrier catalyst required in the reaction between bromine and phenol?

Back 1867

Its phenol ring has sufficient electron density to polarise benzene molecules

Front 1868

What is the name given to a second substitution?

Back 1868

Disubstitution

Front 1869

Describe the reaction of bromine with phenylamine?

Back 1869

It will react rapidally as the –NH2 group activates the ring as the aromatic ring reacts more readily with electrophiles

Front 1870

Draw the reaction of bromine and phenylamine?

Back 1870

Front 1871

Describe the reaction of nitrobenzene and bromine?

Back 1871

They react slowly and require both a halogen carrier catalyst and a high temperature. It is less susceptible to electrophilic substitution than benzene. This is because the NO2 group deactivates the aromatic ring as it reacts less readily with electrophiles

Front 1872

Where does the NH2 group direct the second substituion?

Back 1872

Positions 2 or 4

Front 1873

Describe where the NO2 group directs the second substituent?

Back 1873

Position 3

Front 1874

What are all 2,4 groups?
What is the exception?

Back 1874

They are all activating except halogens

Front 1875

What is position two on the phenol ring called?
What is position four on the phenol ring called?

Back 1875

Ortho and para

Front 1876

What is the third position on the phenol ring called?

Back 1876

Meta

Front 1877

What effect can different groups on the beznene ring have?

Back 1877

A directing effect

Front 1878

Sort these groups into 2 and 4 directing or 3 directing?
NH2 or NHR
COOH
CN
F, CL, BR, I
OR
COOR
NR3^+
NO2
R OR C6H5
OH
RCOR
SO3H
CHO

Back 1878

Front 1879

Why can the directing effect of substituent groups be used when planning an organic synthesis?

Back 1879

You may have to consider the order of reactions to ensure the correct substitution pattern and the required product prepaired

Front 1880

Compare the different reactivities of benzene and alkenes towards chlorine?

Back 1880

1. Alkenes have double carbon to carbon bonds with localised pi–electrons
2. Benzene had delocalised system of pi–bonds
3. Electron density is greater in alkenes so can attract electrophiles such as Cl^–

Front 1881

Describe the sturcture of benzene? Delocalised

Back 1881

1. Planar ring
2. Bond lengths of C–C bonds are the same length
3. Bond angles are 120 degrees

Front 1882

What is the carbonyl functional group?

Back 1882

C=O

Front 1883

What is the name of this functional group: C=O?

Back 1883

The carbonyl group

Front 1884

Where is the functional group found in aldehydes?

Back 1884

At the end of the carbon chain

Front 1885

How is the carbonyl functional group written in aldehydes?

Back 1885

CHO

Front 1886

What is the common name for methanal?


What is its use

Back 1886

Formaldehyde


Presvering biological specimens

Front 1887

Where is the carbonyl functional group found in ketones?

Back 1887

Joined to two carbon atoms in the carbon chain

Front 1888

How is the functional group written in ketones?

Back 1888

CO

Front 1889

What is the common name for propanone?


What is it used as?

Back 1889

Acetone


It is an industrial solvent and in nail varnish removers

Front 1890

What is the suffix for an aldehyde?

Back 1890

al

Front 1891

What is the suffix for a ketone?

Back 1891

–one

Front 1892

In an aldehyde what is the number of the carbon atom of the carbonyl group?

Back 1892

It is always carbon–1

Front 1893

Where does octanal occur naturally?

Back 1893

In citrus oils and is used comercially in poerfumes and flavour production

Front 1894

What bond influences the reactivity of aldehydes and ketones?

Back 1894

The carbon–oxygen bond

Front 1895

Draw the carbonyl bonds structure in aldehydes/ketones! Detail!

Back 1895

Front 1896

What is the carbonyl group C=O bond made up of?

Back 1896

Both a sigma bond and a pi bond

Front 1897

Why do alkenes and carbonyls not react the same way as they both have double bonds in their structures?

Back 1897

1. The C=C double bond in alkenes is non polar
2. The C=O bond in carbonyl compounds is polar

Front 1898

Why is the C=O bond in carbonyl compounds polar?

Back 1898

1. Oxygen is more electronegative than carbon
2. The electron density in the double bond lies closer to the oxygen atom that to the carbon
3. This makes the carbon end of the bond slightly positive and the oxygen end slightly negative

Front 1899

Why can aldehydes and ketones react with some nucleophiles (generally)?

Back 1899

Because of the polarity of the C=O bond

Front 1900

What can aldehydes and ketones react with due to the polarity of the C=O bond?

Back 1900

Some nucleophiles

Front 1901

Describe generally (one sentance) how a nucleophile reacts with a C=O bond?

Back 1901

It is attracted to and attacks the slightly positive carbon atom, resulting in addition across the C=O bond

Front 1902

What is the name of the reaction mechanism of nucleophiles reacting with a carbonyl group?

Back 1902

Nucleophilic addition

Front 1903

Give the difference between how alkenes and carbonyl's react usingthese prompts?


1. What does each react with
2. What mechanism is used

Back 1903

Carbonyls react with nucleophiles whereas alkenes react with electrophiles.


Carbonyls react through nucleophilic addition whereas alkenes react through electrophilic addition

Front 1904

What is used to reduce aldehydes and ketones to alcohols? Give the name and the symbols

Back 1904

Sodium tetrahydrioborate (III) or NaBH4

Front 1905

What conditions are used for the reduction of carbonyl compounds?

Back 1905

The aldehyde or ketone is warmed with the reducing agent NaBH4 in aqueous solution

Front 1906

What happens when an aldehyde is reduced with NaBH4?

Back 1906

A primary alcohol is produced

Front 1907

Give the equation for the reduction of butanal with NaBH4?

Back 1907

Front 1908

What happens when an ketone is reduced with NaBH4?

Back 1908

The are reduced to secondary alcohols

Front 1909

Give the equation for the reduction of propanone with NaBH4?

Back 1909

Front 1910

Name this compound: HCN

Back 1910

Hydrogen cyanide

Front 1911

Give the formula for hydrogen cyanide?

Back 1911

HCN

Front 1912

Describe hydrogen cyanide?

Back 1912

1. Colourless
2. Extremely poisonous liquid
3. Boils slightly abobe room temperature

Front 1913

Why can hydrogen cyanide not be used safetly in a lab?


Therefore what is used in a reaction to provide hydrogen cyanide?


Does this make the reaction safer?

Back 1913

Because it boils slightly above room temperature


Sodium cyanide and sulfuric acid


It is safer but the reaction is still potentially very hazardous

Front 1914

Why is the reaction of carbonyl compounds with HCN useful?

Back 1914

It provides a way of increasing the length of the carbon chain

Front 1915

Give the reaction of propanal with hydrogen cyanide?

Back 1915

Front 1916

Name this compound generally?

Back 1916

Hydroxynitrile

Front 1917

What are the functional groups of the organic product formed from the reaction of an aldehyde with hydrogen cyanide?

Back 1917

A hydroxyl group and anitrile group

Front 1918

What is the name given to the compounds formed from the reaction of an aldehyde with hydrogen cyanide?

Back 1918

Hydroxynitriles or cyanohydrins

Front 1919

Why does the C=O bond attract nucleophiles?

Back 1919

Because it is electron deficient

Front 1920

What is the nucleophile in the nucleophilic addition reaction of aldehydes/ketones with NaBH4?

Back 1920

The hydride ions; H^–

Front 1921

Describe the mechanism of the reaction between NaBH4 and a ketone/aldehyde?

Back 1921

1. Lone pair of electrons from the hydride ion is attracted and donated to the delta positive carbon atom in the C=O bond
2. A dative covalent bond is formed between the hydride ion and the carbon atom of the C=O bond
3. The pi bond in the C=O double bond breaks by heterolytic fission, forming a negatively charged intermediate
4. The oxygen atom of the intermediate donates a lone pair of electrons to a hydrogen atom in a water molecule. The intermediate has then been protonated to form an alcohol

Front 1922

What does protonate mean?

Back 1922

transfer a proton to

Front 1923

Give the mechanism for the reaction between propanone and NaBH4?

Back 1923

Front 1924

What is the cyanide ion?

Back 1924

CN^–

Front 1925

Describe the mechanism for the reaction of carbonyl compounds with NaCN/H^+?

Back 1925

1. The lone pair of electrons from the cyanide ion is attracted to and donated to the delta positive carbon atom in the aldehyde or ketone C=O bond. This forms a dative covalent bond
2. The pi bond in the C=O bond breaks by heterolytic fission forming a negatively charged intermediate
3. The intermediate is protonated by donating a lone pair of electrons to the hydrogen ion to form a hydroxynitrile

Front 1926

Give the mechanism for the reaction of propanal with sodium cyanide in the presence of an acid?

Back 1926

Front 1927

What are the other names for Bradys reagnet?

Back 1927

1. 2,4–dinitrophenylhydrazine
2. 2,4–DNP

Front 1928

What are the other names for 2,4–dinitrophenylhydrazine?

Back 1928

1. Bradys reagent
2. 2,4–DNP

Front 1929

What are the other names for 2,4–DNP?

Back 1929

1. 2,4–dinitrophenylhydrazine
2. Bradys Reagent

Front 1930

What is bradys reagent used to detect?

Back 1930

The presence of the carbonyl functional group in both aldehydes and ketones

Front 1931

Draw the structure of 2,4 NDP?

Back 1931

Front 1932

What reagent is used to detect the presence of the carbonyl functional group in both aldehydes and ketones?

Back 1932

Bradys reagent/2,4 DNP

Front 1933

In the presence of a carbonyl group, what precipitate is formed with bradys reagent?

Back 1933

A yellow or organe precipitate called a 2,4–dinitrophenylhydrazone

Front 1934

What does bradys reagent consist of?


Why?

Back 1934

2,4–DNP dissolved in methanol and sulfuric acid


Solid 2,4–DNP is very hazardous as sudden friction or blow can cause it to explode

Front 1935

What colour is bradys reagent usually?

Back 1935

Pale organe

Front 1936

Give the (step by step) method for testing for a carbonyl group in aldehydes of ketones?

Back 1936

1. Add 5cm excess 2,4–DNP to a clean test tube
2. Add three drops of the unknown compound and leave to stand
3. If no crystals form, add a few drops of sulfuric acid
4. A yellow/orange precipitate indicates the presence of an aldehyde or ketone

Front 1937

What reagent is used to distinguish between an aldehyde and a ketone?

Back 1937

Tollens reagent

Front 1938

What is tollens reagent used for?

Back 1938

To distinguish between aldehydes and ketones

Front 1939

What is tollens reagent chemically?

Back 1939

A solution of silver nitrate in aqueous ammonia

Front 1940

Why must tollens reagent be made up immediatley before carrying out the test?

Back 1940

Because it has a short shelf life

Front 1941

What does tollens reagent produce in the presence of an...
1. Aldehyde
2. Ketone

Back 1941

1. A silver mirror
2. Colourless – no reaction

Front 1942

Give the method of making tollens reagent?

Back 1942

1. Add 3cm depth of aqueous silver nitrate tp a test tube
2. Add sodium hydroxide to the silver nitrate until a brown precipitate of silver oxide is formed
3. Add dilute ammonia solution until the brown precipitate just dissolves to form a clear colourless solution which is tollens reagent

Front 1943

Give the method of using tollens reagent to test for an aldehyde?

Back 1943

1. Pour 2cm of the unknown colution into a clean test tube
2. Add an equal volume of tollens reagent
3. Leave the test tube to stand in a beaker of warm water at 50 degrees for 10 to 15 minutes to observe whether a silver mirror is formed

Front 1944

What ions does tollens reagent contain?


What do these act as in the presence of ammonia?

Back 1944

Silver ions (Ag^+)


Oxidising agents

Front 1945

Why is a silver mirror formed in the reaction between tollens reagent and an aldehyde (chemically)?

Back 1945

Silver ions are reduced to silver as the aldehyde is oxidised to a carboxylic acid

Front 1946

Give the equation that silver ions undergo in the tollens reagent reaction with an aldehyde?

Back 1946

Ag^+ (aq) + e^– ––> (reduction) Ag(s) silver mirror

Front 1947

Give the equation that the aldehyde undergos in the tollens reagent reaction?

Back 1947

Aldehyde + [O] ––> (oxidation) Carboxylic acid

Front 1948

How can the 2,4–dinitrophenulhydrazone precipiate formed in the 2,4–DNP test be used to identify the carbonyl compund?

Back 1948

1. The impure yellow/orange solid is filtered to separate the solid precipitate from the solution
2. The solid is then recrystallised to produce a pure sample of crystals
3. The melting point of the purified 2,4–dinitrophenylhydrazone is measured and recorded
4. This can be compared to a database of melting points to identify the original carbonyl compound

Front 1949

Define a carboxylic acid?

Back 1949

It is an organic acid which contains the carboxyl functional group

Front 1950

What functional groups dose the carboxylic acid contain?

Back 1950

1. A carbonyl group
2. A hydroxyl group

Front 1951

What are carboxylic acids used in?

Back 1951

Organic synthesis as starting materials or intermediates in the formation of more useful compiunds

Front 1952

What is aspirin synthesised from?

Back 1952

Saylic acid

Front 1953

Give the structure and other name of salicylic acid?

Back 1953

Front 1954

Give the structure of aspirin?

Back 1954

Front 1955

Why can carboxylic acids form hydrogen bonds with water molecules?

Back 1955

It conatins C=O and O–H bonds which are polar

Front 1956

Describe the solubility of carboxylic acids with chain length?

Back 1956

1. Carbonxylic acids with up to four carbon atoms are soluble in water
2. As the number of carbon atoms increases, the solubility decreases as the non polar carbon chain has a greater effect on the overall polarity of the molecule

Front 1957

Draw hydrogen bonds between a carbonxylic acid and water molecule?

Back 1957

Front 1958

What are dicarboxylic acids?

Back 1958

Carboxylic acids with two polar carboxyl groups

Front 1959

Which is more soluble, a carboxylic acid or dicarboxylic acid?

Back 1959

Dicarboxylic acids as they have two polar carboxyl groups so can form more hydrogen bonds and therefore readily dissolve in water

Front 1960

What type of acids are carboxylic acids?

Back 1960

They are weak acids

Front 1961

Give the dissociation equation of methanoic acid?

Back 1961

HCOOH ––> <––– H^+ + HCOO^–

Front 1962

What two types of reactions do carboxylic acids take place in?

Back 1962

1. Redox reactions
2. Neutralisation reactions

Front 1963

In redox and neutralisation reactions, what do carboxylic acids form?

Back 1963

Carboxylate salts

Front 1964

What do carboxylic acids undergo redox reactions with?

Back 1964

Metals

Front 1965

What do carboxylic acids undergo neutralisation reactions with?

Back 1965

Bases

Front 1966

How do you name a carboxylate salt?

Back 1966

The –ic acid ending is change to –ate

Front 1967

Draw the structure of a carboxylic acid (general – use R) and then its carboxylate ion?

Back 1967

Front 1968

What is produced when a carboxylic acid reacts with metals?


What type of reaction is this?


What would expect to visually see?

Back 1968

It produces hydrogen gas and a carboxylate salt


Redox reaction


The metal disappearing and effervescence as hydrogen gas is evolved

Front 1969

Give the reaction (equation) of propanoic acid with magnesium?

Back 1969

Front 1970

What happens when carboxylic acids react with metal oxides?


What would you expect to see visually?

Back 1970

A salt and water is formed


Solid metal dissapears

Front 1971

Give the equation for the reaction between ethanoic acid and calcium oxide?

Back 1971

Front 1972

What happens when carboxylic acid react with alkalis?


What would you expect to see visually?

Back 1972

They form a salt and water


Nothing as the two solutions react together to form an aqueous solution of the salt

Front 1973

Give the equation of the reaction between ethanoic acid and sodium hydroxide?

Back 1973

Front 1974

Name this compound?

Back 1974

Sodium ethanoate

Front 1975

What happens when a carbonate is added to a carboxylic acid?


What would you see visually?

Back 1975

A salt, water and Co2 is evolved


If the carboxylic acid is in excess a solid carbonate would disappear, bubbles as CO2 is produced

Front 1976

How can you distinguish carbonxylic acids from any other organic compounds?


Why?

Back 1976

Reaction with carbonates as carboxylic acids are the only common organic compounds sufficiently acidic to react with carbonates.

Front 1977

How can you distinguish carboxylic acids from phenols?

Back 1977

By reaction with carbonates as phenols are not acidic enough to react with carbonates

Front 1978

What is a derivative of a carboxylic acid?

Back 1978

It is a compiund that can be hydrolysed to form the parent carboxylic acid

Front 1979

What is the common sequence of atoms in the structure of a carboxylic acid derivative?


Draw it!

Back 1979

Acyl Group

Front 1980

Draw the general structure of an ester, with the acyl group and the attached electronegative atoms circled.

Back 1980

Front 1981

Draw the general structure of an acyl chloride, with the acyl group and the attached electronegative atoms circled.

Back 1981

Front 1982

Draw the general structure of an acid anhydride, with the acyl group and the attached electronegative atoms circled.

Back 1982

Front 1983

Draw the general structure of an amide, with the acyl group and the attached electronegative atoms circled.

Back 1983

Front 1984

How do you name an ester?

Back 1984

1. The alkyl chain attached to the oxygen atom of the COO group is the first word in the name
2. Remove the oic acid suffix from the parent carboxylic acid and replace with –oate

Front 1985

Name this ester?

Back 1985

Methyl ethanoate

Front 1986

Name this ester?

Back 1986

Ethyl Propanoate

Front 1987

How do you name an acyl chloride?

Back 1987

1. Remove the –oic acid suffix from the parent carboxylic aci
2. Replace with –oyl chloride

Front 1988

Name this compound?

Back 1988

Propanoyl chloride

Front 1989

Name this compound?

Back 1989

Butanoyl chloride

Front 1990

Name this compound?

Back 1990

2,4–dimethylpentanoyl chloride

Front 1991

Name this compound?

Back 1991

2–Hydroxy–4–methylpentanoyl chloride

Front 1992

How is an acid anhydride formed?

Back 1992

By the removal of water from two carboxylic acid molecules

Front 1993

Give the equation for the formation of ethanoic anhydride?

Back 1993

Front 1994

What is esterifcation?

Back 1994

It is the reaction of an alcohol with a carboxylic acid to form an ester

Front 1995

Give the conditions for esterification?

Back 1995

An alcohol is warmed with a caboxylic acid with a small amount of concentrated sulfuric acid which acts as a catalyst

Front 1996

Give the structural formula reaction between propanoic acid and ethanol?

Back 1996

Front 1997

Give the method for making ethyl propanoate?

Back 1997

1. Add 2cm^3 of ethanol and 2cm^3 of propanoic acid into a boiling tube
2. Add a few drops of concentrated sulfuric acid
3. Place the boiling tube in a beaker of hot water at 80 degrees
4. Leave the boiling tube in the water for five minutes
5. Pour the contents of the tube into a beaker containing sodium carbonate to neutralise any left over acid

Front 1998

By what two methods can esters be hydrolysed?

Back 1998

1. Aqueous acid or alkali

Front 1999

Define hydrolysis?

Back 1999

It is the chemical breakdown of a compound in the presence of water of in aqueous solution

Front 2000

Describe acid hydrolysis of an ester (one short sentance)?

Back 2000

It is the reverse of esterification

Front 2001

How do you carry out acid hydrolysis of an ester?

Back 2001

1. The ester is heated under reflux with dilute aqueous acid
2. The ester is broken down by water, with the acid acting as a catalyst

Front 2002

What are the products of acid hydrolysis of an ester?

Back 2002

A carboxylic acid and an alcohol

Front 2003

Give the structural equation for the acid hydrolysis of methyl 2–hydroxybenzoate?

Back 2003

Front 2004

What is alkaline hydrolysis also known as?


What about it is different to it to acid hydrolsysis?

Back 2004

Saponification


It is irreversible and uses hydroxide ions

Front 2005

How does alkaline hydrolysis of an ester occur? CONDITIONS

Back 2005

The ester is heated under reflux with aqueous hydroxide ions

Front 2006

Give the structural equation for the alkaline hydrolysis of methyl ethanoate?

Back 2006

Front 2007

If the alkali in alkaline hydrolysis is sodium hydroxide what is formed if the ester is methyl ethanoate?

Give the equation?

Back 2007

Sodium ethanoate

Front 2008

How can acyl chlorides be prepared from their parent carboxylic acid?

Back 2008

By reaction with thionyl chloride

Front 2009

Give the formula of thionyl chloride?

Back 2009

SOCl2

Front 2010

What are the other products of the reaction of a carbonxylic acid + thionyl chloride?


Therefore where should the reaction be carried out?

Back 2010

SO2 and HCl are evolved as gases, leaving just the acyl chloride


In a fume cupboatd as the products are harmful

Front 2011

Give the structural equation for the formation of propanoyl chrloide form its parent carboxylic acid?

Back 2011

Front 2012

Describe the reacitivity of acyl chlorides?

Back 2012

They are very reactive

Front 2013

Why are acyl chlorides useful in organic synthesis?

Back 2013

They can easily be converted into carboxylic acid derivatives such as amides and esters with good yields

Front 2014

How do acyl chlorides react with nucelophiles (generally)?

Back 2014

By losing the chloride ion whilst retaining the C=O bond

Front 2015

What do acyl chrloides react with alcohols to form?

Back 2015

Esters

Front 2016

Give the structural equation for the reaction between ethanoyl chloride and propan–1–ol?

Back 2016

Front 2017

What happens when a carboxylic acid reacts with phenol?

Back 2017

It dosent, they are not reactive enough

Front 2018

Which is more reactive, acyl chloride/acid anhydride or carboxylic acids?

Back 2018

acyl chlorides/acid anhydrides

Front 2019

What happens when acyl chlorides/acid anhydrides react with phenols?

Back 2019

They produce phenyl esters

Front 2020

What catalyst is needed whenacyl chlorides/acid anhydrides react with phenols?

Back 2020

Neither reaction needs a catalyst

Front 2021

Give the structural equation for the formation of phenyl ethanoate?

Back 2021

Front 2022

Give the structural equation for the reaction of ethanoul chloride and phenol?

Back 2022

Front 2023

What happens generally when water is added to an acyl chloride?

Back 2023

A violent reaction takes place with the evoluation of dense steamy hydrogen chloride fumes and a carboxylic acid is formed

Front 2024

Give the structrual equation for the equation of the reaction ethaonyl chloirde with water?

Back 2024

Front 2025

How can ammonia and amines act as nucleophiles?

Back 2025

By donating the lone pair of electrons on the nitrogen atom to an electron deficient species

Front 2026

What is formed when ammonia and amines react with acyl chlorides?

Back 2026

They form amides

Front 2027

What happens when ammonia reacts with acyl chlorides?

Back 2027

A primary amide is formed

Front 2028

In a primary amine where is the nitrogen atom attached to?

Back 2028

Carbon one atom (terminal carbon)

Front 2029

Give the structural reaction of ethanoyl chloride and ammonia?

Back 2029

Front 2030

Give the structural reaction that forms ethanamide?

Back 2030

Front 2031

What happens when a primary amine reacts with acyl chloride?

Back 2031

A secondary amide is formed

Front 2032

Where is the nitrogen atom attached in a secondary amide?

Back 2032

To two carbon atoms

Front 2033

Define an amine?

Back 2033

In organic chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair.

Front 2034

Give the structural equation of the reaction of ethanoyl chloride and methylamine?

Back 2034

Front 2035

Give the structural equation for the reaction that forms N- methylethanamide?

Back 2035

Front 2036

Are acid anhydrides more or less reactive than acyl chlorides?

Back 2036

Less reactive

Front 2037

Rank these in order of reactivity with 1 being the most reactive: carboxylic acids, acyl chlorides and acid anhydrides

Back 2037

1. Acyl Chlorides
2. Acid anhydrides
3. Carboxylic acids

Front 2038

What does acid anhydrides being less reactive than acyl chlorides mean>?

Back 2038

They can be used for some lab preparations where acyl chlorides may be too reactive

Front 2039

Describe the reactions of acid anhydrides?

Back 2039

They react in the same way as acyl chlorides with alchohols, phenols, water, ammonia and amines.

Front 2040

Acid Anhydride + Alcohol ––>


Acid Anhydride + Ester ––>


Acid Anhydride + Water ––>

Back 2040

Esters


Esters


Carboyxlic acids

Front 2041

Acid Anyhydide + ammonia ––>


Acid anhydride + primary amine ––>

Back 2041

Primary amide


Secondary amide

Front 2042

Give the equation for the reaction of ethanoic anyhride and phenol?

Back 2042

Front 2043

Give the reaction for the formation of phenyl ethanoate from an acid anhydride?

Back 2043

Front 2044

Describe how to set up the apparatus for filtering under reduced pressure? (Including actual filtering)

Back 2044

1. Connect one end of the pressure tubing to the vacuum outlet/filter pump whilst attaching the other end to the buchner flask
2. Fit the buchner funnel to the flask, ensuring there is a good fit using a buchner ring
3. Switch on the tap/vacuum pump
4. Check for good suction by placing your hand across the top of the funnel
5. Place filter paper inside the funnel and wet this with the same solvent used in preparing your solid. It should be sucked down against the holes in the funnel
6. Pour the reaction mixture from a beaker into the center of the filter paper
7. Rinse out the beaker with the solvent so that all of the solid crystals collect in the funnel
8. Rinse the crystals in the funnel with more solvent and leave them under suction for a few minutes so they dry

Front 2045

What will the solid product obtained after filtration contain?

Back 2045

Impurities

Front 2046

How can you remove impurities from the solid product obtained from filtration?

Back 2046

Recrystallisation

Front 2047

What does purification by recrystallisation depend upon?

Back 2047

1. The desired product
2. The impurities having different solubilities

Front 2048

What does purification by recrystallisation depend upon?

Back 2048

The desired product and the impurities having different solubilities

Front 2049

Describe how you distingusih between an activating/deactivating group when added to benzene?

Back 2049

Generally speaking, electron donors / activators have a lone pair of electrons or an electron density that “pushes” into the benzene.

Electron withdrawing / deactivators have a positive charge on the substituent or a very electronegative atom attached to it, which “pulls” electrons out of the benzene.

Front 2050

Why in recrystalisation is the minimum quantity of hot water used?

Back 2050

To ensure the hot solution would be saturated / crystals would form oncooling

Front 2051

Why in recrystallization is the flask left to cool before crystals were filtered off?

Back 2051

Yield lower if warm / solubility higher if warm

Front 2052

Why in recrystallization are the crystals compressed in the funnel:?

Back 2052

Air passes through the sample not just round it

Front 2053

Why in recrystallization is a little cold water poured through the crystals?

Back 2053

To wash away soluble impurities

Front 2054

In distillation, what one thing can you do to minimise loss of product?

Back 2054

Cooled collection vessel necessary to reduce evaporation of product

Front 2055

For a titration requring the addition of 3cm^3 of alkali to reach the end point, how can the experiment be imporved to reduce the percentage uncertaintity?

Back 2055

Use a lower concentration of alkali so that a larger titre is required as this reduces the percentage uncertainty in the titre

Front 2056

What are amines?

Back 2056

They are organic compounds derived from ammonia in which one or more hydrogen atoms in ammonia have been replaced by a carbon chain or ring

Front 2057

Describe an aliphatic amine?

Back 2057

The nitrogen atom is attatched to at least one straight or branched carbon chain

Front 2058

Describe an aromatic amine?

Back 2058

The nitrogen atom is attached to an aromatic ring

Front 2059

What is the simplest aliphatic amine?

Back 2059

Methylamine

Front 2060

What is the simplest aromatic amine?

Back 2060

Phenylamine

Front 2061

Describe and draw a primary amine?

Back 2061

The nitrogen atom is attached to one alkyl group

Front 2062

Describe and draw a secondary amine?

Back 2062

The nitrogen atom is attached to two alkyl groups

Front 2063

Describe and draw a tertiary amine?

Back 2063

The nitrogen atom is attached to three alkyl groups

Front 2064

Name two amines in the body?

Back 2064

1. Serotonin
2. Pseudoephedrine

Front 2065

Describe serotonin?

Back 2065

1. Neurotransmitter
2. Responsible for the control of appetite, sleep, memory and learning
3. Involved in temperature regulation, muscle contraction and depression

Front 2066

Describe Pseudoephedrine?

Back 2066

1. Active ingrediant in decongestion medications
2. Works by shrinking nasal membranes and inhibiting nasal secretions

Front 2067

How do you name a primary amine when the nitrogen is attached to a terminal carbon?

Back 2067

Add the suffix amine to the alkyl chain

Front 2068

How do you name a primary amine when the nitrogen is attached to a carbon within the chain?

Back 2068

Using the prefix amino and a number to indicate the position of the nitrogen

Front 2069

How do you name a tertiary or secondary amine with the same group attached to the nitorgen?

Back 2069

Use di– or tri–

Front 2070

How do you name a tertiary or secondary amine with different groups attached to the nitrogen?

Back 2070

The compound is an N–substituted derivative, so the shorter chains are labelled as N– and the longest chain is the prefix of the –amine

Front 2071

Name this compound?

Back 2071

2 amino butane

Front 2072

Name this compound?

Back 2072

N–methylpropylamine

Front 2073

Name this compound?

Back 2073

N–ethyl–N–methylpropylamine

Front 2074

Name this compound?

Back 2074

Dimethylamine

Front 2075

Name this compound?

Back 2075

Ethylamine

Front 2076

Name this compound?

Back 2076

Propylamine

Front 2077

Name this compound?

Back 2077

Trimethylamine

Front 2078

What gives the unpleasant smell of decay?

Back 2078

Amines and sulfur. Amines are amino acids and are produced when proteins break down into amino acids

Front 2079

What do amines act as in their reactions? Why?

Back 2079

As bases bevause the lone pair of electrons on the nitrogen atom can accept a proton

Front 2080

What happens when an amine accepts a proton in terms of bonds?

Back 2080

A dative covalent bond is formed between the lone pair of electrons on the nitrogen atom and the proton

Front 2081

Draw the reaction of ethylamine with acid (H^+ ions)?

Back 2081

Front 2082

Give the reaction of propylamine with hydrochloric acid?

Back 2082

Front 2083

Gibe the reaction of ethylamine with sulfuric acid?

Back 2083

Front 2084

Give the reaction of ammonia with HCl?

Back 2084

NH3 + HCl ––> NH4^+Cl^–

Front 2085

Why can ammonia act as a nucleophile?

Back 2085

Because it has a lone pair of electrons on the nitrogen atom which allows ammonia to act as a nucleophile

Front 2086

Give the two stages for the formation of primary amines?

Back 2086

1. Salt formation
2. Amine formation

Front 2087

Describe the salt formation stage in the formation of primary amines?

Back 2087

Ammonia reacts to form an ammonium salt by nucleophilic substiution

Front 2088

Describe the amine formation in the preparation of amines?

Back 2088

Aquesous alkali is added to an ammonium salt to generate an amine from the salt

Front 2089

Describe the stage of amine formation in the preparation of amines?

Back 2089

Aquesous alkali is added to an ammonium salt to generate an amine from the salt

Front 2090

What are the essential conditions for this reaction?

Back 2090

1. Ethanol as the solvent as water causes the haloalkane to react to form alcohols

2. Excess ammonia is used which reduces further substitution of the amine group to form secondary and tertiary amines

Front 2091

Give the equation for the formation of methylamine?

Back 2091

Front 2092

Why is this reaction unstable for making a pure primary amine?

Back 2092

Because the product still contains a lone pair of electrons on the nitrogen atom that can react further with a haloalkane to form a secondary amine

Front 2093

Give the reaction of 1–chloropropane with propylamine to form a secondary amine?

Back 2093

Front 2094

How do you form a tertiary amine from a secondary amine?

Back 2094

Further reaction with a haloalkane and then sodium hydroxide

Front 2095

How is phenylamine formed?

Back 2095

By the reduction of nitrobenzene (C6H5NH2) with tin and HCl. This forms the ammonium salt phenylammonium chloride which is then reactef with excess sodium hydroxide to product phenylamine

Front 2096

What are the conditions for the reduction of nitrobenzene?

Back 2096

Heated unde reflux with tin and concentrated HCl and then excess sodium hydroxide

Front 2097

Give the equation for the reduction of nitrobenzene to form phenylamine?

Back 2097

Front 2098

What type of acid is used when making an ester?

Back 2098

CONCENTRATED H2SO4

Front 2099

What is an amino acid?

Back 2099

It is an organic compound conatining both amine and carboxylic acid functional groups

Front 2100

How many common amino acids are there?

Back 2100

20

Front 2101

What is an alpha amino acid?

Back 2101

An amino acid in which the amine group is attached to the second carbon atom

Front 2102

What differs between the 20 amino acids in the body?

Back 2102

The side chain 'R'

Front 2103

What is the general formua of an alpha amino acid?

Back 2103

RCH(NH2)COOH

Front 2104

What are the two less common amino acids? Types not specific amino acids

Back 2104

1. The Beta amino acids in which the amine group is attached to the third carbon
2. The y–amino acids in which the amine group is attached to the fourth carbon

Front 2105

Draw the structure of an alpha amino acid?

Back 2105

Front 2106

What do amino acids form when they react with acid?

Back 2106

Salts

Front 2107

Finish the equation

Back 2107

Front 2108

Finish the equation

Back 2108

Front 2109

Finish the equation

Back 2109

Front 2110

Describe what happens to an amino acid when reacted with an alcohol?

Back 2110

They are esterified and the acidic conditions protonate the basic amine group of the ester

Front 2111

What is an amide the product of the reaction of?

Back 2111

It is the product of the reaction of acyl chlorides with ammonia and amides

Front 2112

Draw a primary amide?

Back 2112

Front 2113

Draw a secondary amide?

Back 2113

Front 2114

Draw a tertiary amide?

Back 2114

Front 2115

Name this?

Back 2115

Propanamide

Front 2116

Name this?

Back 2116

N–metylethanamide

Front 2117

Name this?

Back 2117

N,N–dimethylmethanamide

Front 2118

What is another form of stereoisomerism?

Back 2118

Optical isomerism

Front 2119

In which molecules is optical isomerism found?

Back 2119

Those that contain a chiral centre

Front 2120

What is a chiral center?

Back 2120

A carbon atom that is attached to four different atoms or groups of atoms

Front 2121

What does a chiral center lead to?

Back 2121

The existence of two non–superimposable mirror image structures called optical isomers or enantiomers

Front 2122

What is the other name for optical isomers?

Back 2122

Enantiomers

Front 2123

For each chiral atom there is....

Back 2123

....one pair of optical isomers

Front 2124

Is chirality reserved to carbon atoms?

Back 2124

Nope, it applies to any center that holds attachments that can be arranged as two non–superimposable mirror image forms

Front 2125

Draw the optical isomer of this?

Back 2125

Front 2126

By which method do alkenes form polymers?

Back 2126

Addition polymerisation

Front 2127

Define condensation polymerisation?

Back 2127

It is the joining of monomers with loss of a small molecule, usually water or hydrogen chloride. In a condensation polymersiation two different functional groups are needed

Front 2128

What is the requirement for condensation polymerisation?

Back 2128

The monomers must have two different functional group

Front 2129

Name two important condensation polymers made on an industrial scale?

Back 2129

1. Polyesters
2. Polyamides

Front 2130

Whart are the common starting material for the polymerisation of polyesters and polyamides?

Back 2130

Carboxylic acids and their derivatives

Front 2131

How are momnomers joined together in polyesters?

Back 2131

By ester linkages

Front 2132

Which two ways can a polyester be formed?

Back 2132

1. One monomer containing both a carboxylic acid and an alcohol group
2. From two monomers, one containing two carboxylic acid groups and the other containing two alcohol groups

Front 2133

When polyesters are made from a monomer containing two different functional groups, how many monomers are involved?


What does it contain in terms of functional groups?

Back 2133

On monomer


A hydroxyl group –OH and a carboxyl group –COOH

Front 2134

Poly(glycolic acid) is the simplest polyester made from one monomer of glycolic acid, HOCH2COOH. Draw the condensation reaction?

Back 2134

Front 2135

Describe which bits are reacting where here?

Back 2135

The carboxylic acid group in one molecule of glycolic acid reacts with the alcohol group of another molecule of glycolic acid to form the ester linkage and water

Front 2136

Where is lactivc acid derived from?




How does this make it different?

Back 2136

From maize


Its production is more sustainable than polymers derived from fossil fuels

Front 2137

When polyesters are made from monomers containing two different functional groups, how many monomers are involved?

What does it contain in terms of functional groups?

Back 2137

Two different monomers are involved with different functional groups


One monomer is a diol, one monomer is a dicarboxylic acid

Front 2138

Draw the condensation polymerisation reaction between benzene–1,4–carboxylic acid and ethane–1,2–diol?


What is the name of the polymer?

Back 2138

Terylene

Front 2139

Describe what is happening in this image?

Back 2139

A hydroxyl group on the diol reacts with a carboxyl group on the dicarboxylic acid forming an ester linkage and water

Front 2140

Decribe terylene generally?

Back 2140

1. Shortened to PET
2. Used in clothing such as sports clothes
3. USed for electrical insulation
4. Used in plastic bottles

Front 2141

Name two biodegradable polymers?

Back 2141

PLA (polylactic acid) and PGA (poluglycolic acid)

Front 2142

Give a used of PLA/PGA?

Back 2142

Sutures to close wounds after surgery of injury

Front 2143

Define polyamides?

Back 2143

They are condensation polymers formed when monomers are joined together by amide linkages in a long chain to form the polymer

Front 2144

Give the two ways in which a polyamide can be formed?

Back 2144

1. From one monomer containing both a carboxylic acid or acyl chloride and an amine group
2. From two monomers with one containing two carboxylic acid groups or acyl chlorides and the other containing two amine groups

Front 2145

Describe why and how amino acids undergo condensation polymersiation?

Back 2145

1. They conatin both an amine group and a carboxylic acid group
2. They undergo condensation polymerisation to form polypeptides or proteins

Front 2146

What is formed when an amide bond is formed from a carboxylic acid?

Back 2146

Water is lost

Front 2147

Finish this condensation reaction?

Back 2147

Front 2148

Draw an amide linkage?

Back 2148

Front 2149

Draw 1,6–diaminohexane?

Back 2149

Front 2150

Draw hexanedioic acid?

Back 2150

Front 2151

Draw hexanedioyl chloride?

Back 2151

Front 2152

Finish this condensation reaction?

Back 2152

Front 2153

Finish this condensation reaction?

Back 2153

Front 2154

How can different types of nylon be made?

Back 2154

By varying the carbon chain length

Front 2155

What are the two ways to make nylon? (non–specific)

Back 2155

1. With a dicarboxylic acid and diamine
2. With an acyl chloride and a diamine

Front 2156

What are the two ways to hydrolyse condensation polymers?

Back 2156

1. Hot aqueous alkali (NaOH)
2. Hot aqueous acid (HCl)

Front 2157

What is poly(trimethylene Terephthelate) or PTT used in?

Back 2157

1. Carpets
2. Clothing fabrics

Front 2158

Give the acid hydrolysis of PTT?

Back 2158

Front 2159

Give the base hydrolysis of PTT?

Back 2159

Front 2160

Give the base hydrolyiss of nomex?

Back 2160

Front 2161

Give the acid hydrolysis of nomex?

Back 2161

Front 2162

Give uses of nomex?

Back 2162

1. Synthetic heat and fire retardant polyamide
2. Oven gloves
3. Fire protective formula 1 suits

Front 2163

Give the characteristics of additions vs condensation polymerisation?

Back 2163

Addition:
1. Monomer contains C=C bond
2. Backbone of polymer is a continous chain of carbon atoms
Condensation:
1. Two monomers each with two functional groups of one monomer with two different functional groups
2. Polymers contain ester or amide linkages

Front 2164

Why are polymers formed by addition polymerisation descirbed as non–biodegradable?

Back 2164

1. The C–C backbone is non polar
2. It does not undergo hydrolysis
3. It therefore cannot be broken down by microbes

Front 2165

Why are polyamides descirbed as being biodegradable?

Back 2165

1. The carbonyl group in the amide link has a dipole
2. This makes it susceptible to nucleophilic attack
3. This means it can undergo hydrolysis

Front 2166

How can you distinguish between two optical isomers?

Back 2166

They rotate plane polarised light in opposite directions

Front 2167

Give the uses of Nylon?

Back 2167

It is a high strength fibre used for...
1. Making fishing nets
2. Ropes
3. Parachutes
4. Fabrics
5. Classical guitar strings

Front 2168

Why are reactions that form carbon–carbon bonds important?

Back 2168

Because they provide a means of synthesising new compounds containing more carbon ayoms

Front 2169

Give the nitrile functional group?

Back 2169

Front 2170

Give the two ways you can form a nitrile?

Back 2170

1. From a haloalkane
2. From aldehydes and ketones

Front 2171

When a nitrile is formed from a haloalkane what is the difference between the starting and the final molecule?

Back 2171

The length of the carbon chain has been increased

Front 2172

When a nitrile is formed from an aldehyde or ketone what is the difference between the starting and the final molecule?

Back 2172

The number of carbon atoms in the molecule has been increased

Front 2173

What are the conditions for the formation of nitriles from haloalkanes?

Back 2173

1. Haloalkane
2. Sodium cyanide (NaCN)
3. Potassium cyanide (KCN)
4. In ethanol

Front 2174

Give the equation for the formation of buntanenitrile?

Back 2174

Front 2175

Give the equation for the formation of buntanenitrile from a chloroalkane

Back 2175

Front 2176

Name this?

Back 2176

2–methylpropanenitrile

Front 2177

Name this?

Back 2177

prop–2–enenitrile

Front 2178

Give the mechanism for the formation of butanenitrile from 1–chloropropane?

Back 2178

Front 2179

Give the mechanism for the formation of propanenitrile?

Back 2179

Front 2180

Give the mechanism for the formation of propanenitrile from a haloalkane?

Back 2180

Front 2181

The reaction for the formation of a nitrile from aldehydes and ketones is an example of...

Back 2181

... nucleophillic addition

Front 2182

Give the equation for the formation of a hydroxynitrile from propanone? HCN

Back 2182

Front 2183

What is the other name form a hydroxynitrile?

Back 2183

A cyanohydrin

Front 2184

Why do the conditions for nitriles from aldehydes and ketones not use hydrogen cyanide?

Back 2184

1. Hydrogencyanide is far too poisonous to use
2. Increased reaction rate is obtained in the presence of cyanide ions

Front 2185

Because hydrogen cyanide cannot be used to obtain nitrile from aldehydes and ketones, what are the acutal conditions for the reaction?

Back 2185

Sodium cyanide NaCN and sulfuric acid

Front 2186

Why are sodium cyanide and sulfuric acid used to obtain nitriles from aldehydes and ketones?

Back 2186

1. Improves safety
2. Increases reaction rate (due to presence of cyanide ions)

Front 2187

Give the mechanism for the formation of a hydroynitrile from propanone?

Back 2187

Front 2188

Why are nitriles useful?

Back 2188

As intermediates in the synthesis of other organic compounds such as amines and carboxylic acids

Front 2189

What conditions are needed form the reduction of nitriles?

Back 2189

1. Hydrogen
2. Nickel catalyst

Front 2190

What is formed when a nitrile is reduced?

Back 2190

An amine

Front 2191

Give the equation of the reduction of propanenitrile?

Back 2191

Front 2192

Give the equation for the reduction of ethanenitrile?

Back 2192

Front 2193

What are the conditions to form a carboyxlic acid from a nitrile>

Back 2193

1. Heating
2. Dilute aqeous acid

Front 2194

The formation of a carboxylic acid from a nitrile is an example of?

Back 2194

Hydrolysis

Front 2195

Give the equation for the hydrolysis of butanenitrile using HCl?

Back 2195

Front 2196

Give the equation for the hydrolysis of ethanenitrile using HCl?

Back 2196

Front 2197

Give two examples of reactions where nitriles are useful intermedicates?

Back 2197

1. In their reduction to form amines
2. In their hydrolysis to form carboxylic acids

Front 2198

Why do chemists determine the melting point of a solid?

Back 2198

To identify whether it is pure

Front 2199

Describe the melting point of a pure solid?

Back 2199

It has a very sharp melting range of one or two degrees

Front 2200

What is the melting range?

Back 2200

The difference between the temperature at which a sample starts to melt and the temperature at which melting is complete

Front 2201

Describe the melting point of an impure solid?

Back 2201

The solid melts over a wide range of temperature and has a lower melting point than a pure sample

Front 2202

Give the method of preparing a sample for melting point determination?

Back 2202

1. Ensure the sample is completely dry and free flowing
2. Take a glass capillary tube or melting tube. Hold one end in the hot flame of a bunsen burner and rotate until the end of the tube is sealed
3. The capillary tube is allowed to cool and is then filled with crystals of a 3mm depth. This is done by pushing the open end into the solid sample to force it into the tube
4. Determine the melting point either using electrically heated apparatus or using an oil bath or thiele tube

Front 2203

Give the method of using electricaly heated apparatus to determine the melting point of a solid? (no method of preparation)

Back 2203

1. Place the capillary tube containing the sample into a sample hole and a 0–300 degrees thermometer in the themometer hole of the apparatus
2. Using the rapid heating setting, heat up the sample whilst observing it through the magnifying window
3. Once the solid is seen to melt record the melting point and allow apparatus to cool
4. Prepare a second sample and place in melting point apparatus and heat up again
5. As the melting point is approached, set to low and raise the temperature slowly whilst observing the sample so an accurate determination of the melting point can be obtained

Front 2204

Give the method of using a thiele tube to determine the melting point of a solid? (no method of preparation)

Back 2204

1. Set up the thiele tube
2. Attach the capillary tube containing the sample to a thermometer using a rubber band
3. Insert the thermometer through a hole in the cork with the end of the thermometer and capillary tube dipped into the oil
4. Using a micro–burner heat the side arm of the thiele tube whilst observing the solid. When the solid starts to melt remove the heat and record the temperature at which all of the solid has melted. It is important to heat the oil slowly when approaching the melting point and repeat a second time to ensure you get an accurate value

Front 2205

Give the method of using an oil bath to determine the melting point of a solid? (no method of preparation)

Back 2205

1. Set up the oil bath 2. Attach the capillary tube containing the sample to a thermometer using a rubber band
3. Clamp the thermometer with the end of it and capillary tube dipped into the oil
4. Using a micro–burner heat the soil bath whilst observing the solid. When the solid starts to melt remove the heat and record the temperature at which all of the solid has melted. It is important to heat the oil slowly when approaching the melting point and repeat a second time to ensure you get an accurate value

Front 2206

Identify the functional groups in aspartame (artifical sweetener)?

Back 2206

1. Ester

2. Amide

3. Aime

4. Carboxylic acid

Front 2207

Identify the functional groups in capsaicin (spice)?

Back 2207

1. Phenol

2. Ether – OCH3

3. Amide

4. Alkene

Front 2208

Fill in the blanks!

Back 2208

Front 2209

Fill in the blanks!

Back 2209

Front 2210

Fill in the blanks!

Back 2210

Front 2211

Fill in the blanks!

Back 2211

Front 2212

Fill in the blanks!

Back 2212

Front 2213

Fill in the blanks!

Back 2213

Front 2214

Devise a flow chart to show how a sample of ethanamide could be prepared from chloroethane stating all reagents?

Back 2214

Front 2215

Devise a synthesis of butanoic acid from propanal, stating the reagents and conditions and giving suitable conditions for each step

Back 2215

Front 2216

Give the reaction shceme stating all reagents for the synthesis of 1–(3–aminophenyl)ethanol from benzene?

Back 2216

Front 2217

Name this compound?

Back 2217

Benzoic acid

Front 2218

Name this compound?

Back 2218

Phenylamine

Front 2219

Name this compound?

Back 2219

2–phenyloctane

Front 2220

Name this compound?

Back 2220

phenylethanone

Front 2221

Name this compound?

Back 2221

benzaldehyde

Front 2222

Draw the reaction (not mechanism) between benzene and ethanoyl chloride?

Back 2222

Front 2223

What two phases does all chromotography have?

Back 2223

1. Stationary phase
2. Mobile phase

Front 2224

What is chromotography designed to do?

Back 2224

Seperate individual components from a mixture of substances

Front 2225

Describe the staionary phase of chromotography?

Back 2225

It does not move and is usually a solid or a liquid supported on a solid

Front 2226

Describe the mobile phase of chromotography?

Back 2226

It does move and is usually a liquid or a gas

Front 2227

Briefly give the real world applications of chromotography?

Back 2227

In the analysis of
1. Drugs
2. Plastics
3. Flavourings
4. Air samples


It also has applications in forensic science

Front 2228

What does thin layer chromatography use to separate compounds?

Back 2228

A thin layer chromatography plate which is usually a plastic sheet or glass coated with a thin layer of solid adsorbent substance which is usually silica

Front 2229

What does thin layer chromotography indicate?

Back 2229

The number of components in a mixture

Front 2230

What is the stationary phase in thin layer chromotography?

Back 2230

The adsorbent

Front 2231

What is the mobile phase in thin layer chromatography?

Back 2231

The solvent which moves up the paper

Front 2232

Define adsorption in terms of thin layer chromatography?

Back 2232

It is the process by which the solid silica holds the different substances in the mixture to its surface

Front 2233

How is seperation achieved in thin layer chromotography?

Back 2233

Due to the relative adsorptions of the substances with the stationary phase (a thin layer of solid adsorbent usually silica)

Front 2234

What is thin layer chromotography?

Back 2234

It is a quick and inexpensive analytical technique that indicates how many components are in a mixture

Front 2235

Describe the different interactions between components in the mixture and the stationary phase during thin layer chromotography?

Back 2235

The different components in the mixture have different affinities for the absorbent and bind with differing strengths to its surface

Front 2236

Describe the process of carryingout out TLC?

Back 2236

1. Take a TLC plate and draw a line across it 1cm from one the of the plate, this is the base line.
2. Using a capillary tube, spot a small amount of solution of the sample onto the base line on the plate
3. Prepare a chromatography tank using a small beaker with a watch glass placed on the top. Pour a depth of 0.5cm of solvent into the beaker, cover the beaker with a watch glass and leave it undisturbed on the bench, the solvent will rise up the TLC plate
4. Allow the solvent to rise up the plate until it is about 1cm below the top. Remove the plate from the beaker and mark the solvent front with a pencil. Allow the plate to dry
5. Circle visible spots with a pencil, hold the plate under a UV lamp and circle any spots. Spray with a locating agent such as iodine to show the position of spots not visible to the naked eye

Front 2237

How do you analyse thin layer chromatograms? Detailed response

Back 2237

By calculating the value for the retention factor for each component. Each component can be identified by comparing its Rf value with known values recorded using the same solvent system and absorbent

Front 2238

What is the equation for calculation of the Rf value?

Back 2238

=distance moved by component/distance moved by solvent front

Front 2239

Why is analysis of a TLC plate would you might not need to calculate Rf values?

Back 2239

Common to run TLC of a sample alonsdie pure samples of compounds that may be present, it is therefore easy to identify compounds visually without needing to calculate Rf values

Front 2240

What is gas chromotography?

Back 2240

It is a useful method of separating and identifying volatile organic compounds present in a mixture

Front 2241

What is the stationary phase in gas chromotography?

Back 2241

It is a high boiling liquid adsorbed onto an inert solid support

Front 2242

What is the mobile phase during gas chromatography?

Give an example of two chemicals which can be this?

Back 2242

An inert carrier gas such as helium or neon

Front 2243

Describe the process of gas chromatography? Whole thing!

Back 2243

1. Small amount of volatile mixture is injected into the apparatus called a gas chromatograph
2. Mobile carrier gas carries the components in the sample through the capillary column which contains the liquid stationary phase adsorbed onto the solid support
3. The components slow down as they interact with the liquid stationary phase. The more soluble the component is in the liquid stationary phase, the slower it moves through the capillary column
4. Mixture is separated depending on the solubility of the components in the liquid stationary phase
5. Compounds in the mixture reach the detector at different times depending on their interactions with the stationary phase in the column
6. The compounds retained in the column for the shortest time has the lowest retention time and is detected first

Front 2244

Define volatile?

Back 2244

Easily evaporated at normal temperatures

Front 2245

What is the retention time?

Back 2245

It is the time taken for each component in a mixture to travel through the gas chromotography column

Front 2246

Depending on what, are components separated during gas chromotography?

Back 2246

Depending on their solubility in the liquid stationary phase

Front 2247

What is the difference between adsorbtion and absorbtion?

Back 2247

Adsorbtion is when is 'sticks' to the surface and absorbtion is when it moves into the substance

Front 2248

What two pieces of information can be obtained from a gas chromatogram?

Back 2248

1. Retention times
2. Peak integrations

Front 2249

What can retention times be used to do?

Back 2249

Identify compounds present in the sample by comparing these to retention times for known components

Front 2250

What can peak intergrations be used to determine in chromatography?

Back 2250

The concentrations of components in the sample

Front 2251

How do you determine the concentration of a component in a sample using gas chromatography? Summary not method

Back 2251

By comparing its peak integration with values obtained from standard solutions of the component

Front 2252

Give the procedure for determing the concentration of a component in a sample using gas chromatography?

Back 2252

1. Prepare standard solutions of known concentrations of the compound being investigated
2. Obtain gas chromatograms of each standard solution
3. Plot a calibration curve of peak area against concentration this is called external calibration
4. Obtain a gas chromatogram of the compound being investigated under the same conditions
5. Use the calibration curve to measure the concentration of the compound

Front 2253

Describe external calibration?

Back 2253

When you plot a calibration curve of peak area against concentration. This offers a method for converting a peak area into a concentration

Front 2254

What is the test for an alkene and what is the observation?

Back 2254

Add bromine water drop–wise. Bromine water decolourised from orange to colourless

Front 2255

What is the test for a haloalkane and what is the observation?

Back 2255

Add silver nitrate and ethanol and warm to 50 degrees in a water bath.
Chloroalkane – white precipitate
Bromoalkane – cream precipitate
Iodoalkane – yellow precipitate

Front 2256

What is the test for a carbonyl and what is the observation?

Back 2256

Add 2,4–dinitrophenylhydrazine
Orange precipitate

Front 2257

What is the test for an aldehyde and what is the observation?

Back 2257

Add tollens reagent and warm. Silver mirror

Front 2258

What is the test for an primary and secondary alcohol and aldehyde and what is the observation?

Back 2258

Add acidified potassiun dichromate and warm in a water bath.


Colour changes from orange to green

Front 2259

What is the test for a carboxylic acid and what is the observation?

Back 2259

Add aqueous sodiunm carbonate and you see effervesence

Front 2260

What does NMR spectroscopy stand for?

Back 2260

Nuclear magnetic resonance

Front 2261

What did the invention of NMR spectroscopy revolutionise?

Back 2261

The analysis or organic compounds

Front 2262

Briefly describe what NMR uses and what this does and how this can be measured?

Back 2262

1. Uses combination of strong magentic fields and radio frequency radiation
2. The nuclei of atoms absorb this radiation with the right magnetic field strength and frequency
3. The energy for the absorption can be measured and recorded as an NMR spectrum

Front 2263

What is nuclear spin?

Back 2263

The spinning of the nucelus, much like how electrons have spin

Front 2264

When is nucelar spin significant?

Back 2264

If there is an odd number of nucleons

Front 2265

What is a nucelon

Back 2265

A proton or neutron.

Front 2266

Which isotopes of carbon and hydrogen is NMR relevant to?

Back 2266

Those with an odd number of nucelons...
So 1H and 13C

Front 2267

What other elements apart from carbon and hydrogen can NMR be used to detect>

Back 2267

19F and 31P

Front 2268

Why is 1H NMR referred to a proton NMR?

Back 2268

Because the 1H nucelus consists of just a proton

Front 2269

Describe the spin states of electrons?

Back 2269

It has two different spin states, clockwise and anticlockwise. These have different energies because one is aligned with that of the nucelus and one is against it

Front 2270

Describe the upper two lines?

Back 2270

The spin of the nucelus is opposing the direction of the magnetic field. As the strength of the field increases the energy state of the nucleus increases

Front 2271

Describe the lower two lines?

Back 2271

The spin of the nucleus is aligned with the magnetic field. As the strength of the magnetic field increases the energy decreases

Front 2272

Describe the spin states of the nucelus?

Back 2272

It has two different spin states with different energies

Front 2273

What is resonance?

Back 2273

When the nucleus absorbes energy and rapidally flips between the two spin states

Front 2274

What environment is needed to cause resonance

Back 2274

The right combination of a strong magnetic field and radio frequency radiation

Front 2275

Why does the nucelus have a magnetic field?

Back 2275

Because the nucelons spin. The direction of the magnetic field changes depending of the direction of the spin and so is different for each atom

Front 2276

Describe the energy of the radiation used in NMR vs infrared?

Back 2276

Radio frequency has much less energy that infrarer radiation

Front 2277

Describe the frequency of resonance and magentic field strength?

Back 2277

1. Frequency required for resonance is proportional to the magnetic field strength
2. It is only in strong and uniform magnetic fields that this small quantity of energy can be detected
3. A very strong super conduction electromagnetic is used to do this, which has been cooled to 4K by liquid helium

Front 2278

How is the energy needed for resonance detected?

Back 2278

Using a very strong super conduction electromagnet cooled to 4K by liquid helium

Front 2279

What frequency do most rountine NMR spectrometers operate at?

Back 2279

RAdio frequencies of 100, 200 or 400 MHz

Front 2280

Where are NMR spectromeres found in hospitals?

Back 2280

In MRI body scanners

Front 2281

All carbon and hydrogen atoms in an organic molecule are bonded to other atoms, what does this mean in terms of NMR and chemical shift?

Back 2281

All atoms have electrons surrounding the nucelus which shifts the energy and radio frequency needed for nuclear magnetic resonance to take place

Front 2282

The shift in energy and radio frequency needed for NMR is measured on a scale called...


With units...

Back 2282

Chemical shift


Parts per million (ppm)

Front 2283

What is the standard referance chemical against which all chemical shifts are measured?

Back 2283

Tetramethylsilance (TMS) (CH3)4Si

Front 2284

Draw tetramethylsilance?

Back 2284

Front 2285

What is tetramethylsilance?

Back 2285

IS it the standard referance chemical against which all chemical shifts are measured. It is given a chemical shift value of 0ppm

Front 2286

All atoms have electrons surronding the nucelus, which shifts the energy and radio frequency needed for NMR to take place.


Translate into Jade.

Back 2286

1. Atoms have electrons, the electrons of bonded atoms can influence the resonance of the nucelus of that atom (change the amount of energy needed to flip between the two energy states)
2. This changes the frequency of radio waves needed to cause nuclear magnetic resonance

Front 2287

Describe nucelar magnetic resonance?

Back 2287

1. Nucelus has two different spin states with different energies
2. The nucelus can absorb energy with the right combination of a strong magnetic field and radio frequency radiation
3. This allows it to flip between the two spin states
4. This is called resonance and so the whole process is given the name nuclear magnetic resonance

Front 2288

What determines the amount of chemical shift in NMR spectroscopy?

Back 2288

The chemical environment of the atoms, especially the persence of nearby electronegative atoms

Front 2289

So depending on the chemical environment, what does NMR require?


What does this allow chemists to do?

Back 2289

Different energy and frequency and so produces peaks at different chemical shifts


Map out the hydrogen and carbon arrangement in a molecule without needing to carry out conventional chemical tests and destroying the organic compound through doing so

Front 2290

Describe the process of running an NMR sample?

Back 2290

1. Sample is dissolved in a solvent and placed in a narrow NMR sample tube with a small amount of tetramethysilane (TMS)
2. Tube is placed inside NMR spectrometer where it is spun to even out any imperfections in the magnetic field within the sample
3. Spectrometer is zeroed against the TMS standard
4. Sample is given a pulse of radiation containing a range of radio frequencies whilst maintaining a constant magnetic field
5. Any absorptions of energy resulting from resonance are detected and displayed on a computer screen
6. The sample can be recovered by evaporation of the solvent

Front 2291

Can the sample be recovered from NMR soectroscopy? How?

Back 2291

Yes, by evaporation of the solvent

Front 2292

Define a deuterated solvent?

Back 2292

A deuterated solvent is a small molecule in which the hydrogen atoms contained in the solvent molecule have been replaced by its heavier stable isotope deuterium.

Front 2293

What atoms are found in common solvents?


What is the problem with this in NMR spectroscopy?

Back 2293

Carbon and hydrogen atoms


Produce a signal in both 13C and 1H NMR spectra

Front 2294

How do you overcome the fact that most common solvents contain hydrogen and carbon and so will produce a singal inboth 13C and 1H NMR spectra?

Back 2294

A deuyterated solvent is used, in which 1H atoms are replaced by 2H atoms (deuterium, D). This produces no NMR singla in the frequency ranges used in 1H and 13C NMR

Front 2295

What is commonly used as a solvent in NMR spectroscopy?

Back 2295

CDCl3, however this will still produce a peak in the 13C spectrum. The computer usuallt filters out this peak before displaying the spectrum

Front 2296

What two things does carbon –13 NMR spectroscopy tell us about a molecule?

Back 2296

1. Number of different carbon environents, from the number of different peaks
2. The types of carbon environment present, from the chemical shifts

Front 2297

Describe how chemical shift might be outside of the ranges given in the formula book?

Back 2297

Depends on the solvent, concentration and substituents used

Front 2298

Describe how the chemical environment of a carbon atom is determined by the position of the atom within the molecule?

Back 2298

1. Carbon atoms that are bonded to different atoms or groups of atoms have different environmentsand will absorb at different chemical shifts
2. If two carbon atoms are positioned symmetrically within a molecules, then they are equivalent and have the same chemical environment so will absorb radiation at the same chemical shift and contribute to the same peak

Front 2299

Describe the different chemical environments in the carbon–13 NMR spectra?

Back 2299

1. Carbon one is part of the CHO functional group

2. Carbon 2 is part of the CH2 functional group

3. Carbon 3 is part of a CH3 group bonded to CH2CHO4. There are therefore three different chemical environments so will be three peaks in its spectra

Front 2300

Describe the different chemical environments in the carbon–13 NMR spectra?

Back 2300

1. Carbon 2 is part of the C=O group

2. The other two carbons have the same environment as they are positioned symmetrically

3. There are therefore two different chemical environments so will be two peaks in its spectra

Front 2301

Page 517

Back 2301

Front 2302

Predict the number of peaks in its carbon 13 NMR spectrum and approximate chemical shifts for each peak?


Page 518 need data sheet

Back 2302

Front 2303

Predict the number of peaks in its carbon 13 NMR spectrum and approximate chemical shifts for each peak?

Page 518 need data sheet

Back 2303

Front 2304

Predict the number of peaks in its carbon 13 NMR spectrum and approximate chemical shifts for each peak?

Page 518 need data sheet

Back 2304

Front 2305

Predict the number of peaks in its carbon 13 NMR spectrum and approximate chemical shifts for each peak?

Page 518 need data sheet

Back 2305

Front 2306

What four important pieces of information does proton NMR provide about a molecule.

Back 2306

1. The number of different proton envrionments fro the number of peak
2. Types of proton environments present from the chemical shift
3. Relative numbers of each type of proton from integration traves or ratio number of the relative peak areas
4. Number of nonequivalent protons adjacent to a give proton from the spin spin splitting pattern

Front 2307

What may move a peak outside of its range on the data sheet in proton NMR?

Back 2307

Solvent concentration and substituents

Front 2308

Describe equilvalent protons in proton NMR?

Back 2308

If two or more protons are equivalent (they are in the same chemical environment) they will absorb at the same chemical shift, increasing the size of the peak

Front 2309

Describe non equivalent protons?

Back 2309

If two or more protons are non–equivalent (they are in different ehcmical environments) they will absorb at different chemical shifts

Front 2310

Describe equivalent and non equivalent protons?

Back 2310

1. Two CH2 groups are in different environments because they are connected to different groups on either side, this meaning the protons are non equivalnet

2. There is no plane of symmetry and there are four protons environments, giving four peaks in the spectrum

Front 2311

Describe equivalent and non equivalent protons, peaks in the spectrum and relative peak areas?

Back 2311

1. The two CH2 groups are in the same environment, connected to a CH2 group on one side and a COOH group on the other

2. The symmetry means there are two proton environments, one for the COOH protons and one for the CH2 protons

3. The spectrum will have two peaks, with the CH2 having twice the area because it has 4 protons and the COOH has 2 protons

Front 2312

In carbon–13 NMR what is the peak area linked to?

Back 2312

IT IS NOT LINKED to the number of carbon atoms responsible for the peak

Front 2313

In proton NMR what is the peak area linked to?

Back 2313

The ratio of relative areas under each peak gives the ratio of the number of protons responsible for each peak

Front 2314

How does the NMR spectrometer measure the area under each curve?

Back 2314

As an integration trace

Front 2315

Define spin spin coupling? (once sentence)

Back 2315

It is the splitting of the meain peak into sub peaks

Front 2316

What is the difference between spin spin coupling and spin spin splitting?

Back 2316

No difference, they are the same thing

Front 2317

Define spin spin splitting?

Back 2317

It is the splitting of the meain peak into sub peaks

Front 2318

A proton NMR peak can be split into sub peaks or splitting patterns, why?

Back 2318

Due to the protons spin interacting with the spin states of nearby protons that are in different environments

Front 2319

How many sub peaks are produced from a main peak in spin spin coupling?

Back 2319

The number of sub peaks is one greater than the number of adjacent protons causing splitting, this is called the n+1 rule

Front 2320

Give the n+1 rule?

Back 2320

For a proton with n protons attacthed to an adjacent carbon atom, the number of sub peaks in a splitting pattern = n+1

Front 2321

Finish this table for spin spin splitting patterns from n=0 to n=3

Back 2321

Front 2322

What is the name given to the splitting pattern in spin spin coupling which produces one peak?

Back 2322

Singlet

Front 2323

What is the name given to the splitting pattern in spin spin coupling which produces two peaks?

Back 2323

Doublet

Front 2324

What is the name given to the splitting pattern in spin spin coupling which produces three peaks?

Back 2324

Triplet

Front 2325

What is the name given to the splitting pattern in spin spin coupling which produces four peaks?

Back 2325

Quartet

Front 2326

Draw a singlet?

Back 2326

Front 2327

Draw a doublet?

Back 2327

Front 2328

Draw a triplet?

Back 2328

Front 2329

Draw a quartet?

Back 2329

Front 2330

What is the relative peak areas within splitting for a singlet?

Back 2330

1

Front 2331

What is the relative peak areas within splitting for a doublet?

Back 2331

1:1

Front 2332

What is the relative peak areas within splitting for a triplet?

Back 2332

1:2:1

Front 2333

What is the relative peak areas within splitting for a quartet?

Back 2333

1:3:3:1

Front 2334

What does a singlet mean in terms of structural features?

Back 2334

No H on adjacent atoms

Front 2335

What does a doublet mean in terms of structural features?

Back 2335

Adjacent CH

Front 2336

What does a triplet mean in terms of structural features?

Back 2336

Adjacent CH2

Front 2337

What does a quartet mean in terms of structural features?

Back 2337

Adjacent CH3

Front 2338

n+1 = 7


Splitting Pattern:
Areas:
Pattern:
Structural features:

Back 2338

heptet
1:2:3:2:1
Adjacent CH(CH3)2

Front 2339

What is it called when the splitting pattern in spin spin coupling is greater than 4?

Back 2339

Multiplet

Front 2340

How do multiplets arise?

Back 2340

When carbons have adjacent protons in different chemical environments, causing the central peak to be split differently by each group

Front 2341

Why do splitting patterns always occur pin pairs in spin spin coupling?

Back 2341

Because adjacent protons split the signal of the other

Front 2342

Draw the splitting patterns in spin spin coupling for CH2–CH3?

Back 2342

Front 2343

Draw the splitting patterns in spin spin coupling for CH–CH2?

Back 2343

Front 2344

Draw the splitting patterns in spin spin coupling for CH–CH2?

Back 2344

Front 2345

Draw the splitting patterns in spin spin coupling for CH–CH?

Back 2345

Front 2346

Draw the splitting patterns in spin spin coupling for CH–CH3

Back 2346

Front 2347

Draw the splitting patterns in spin spin coupling for CH2–(CH3)2?

Back 2347

Front 2348

Draw the structure from this splitting in proton NMR?

Back 2348

CH2–CH2

Front 2349

Draw the structure from this splitting in proton NMR?

Back 2349

CH–CH2

Front 2350

Draw the structure from this splitting in proton NMR?

Back 2350

CH2–CH2

Front 2351

Draw the structure from this splitting in proton NMR?

Back 2351

CH–CH

Front 2352

Draw the structure from this splitting in proton NMR?

Back 2352

CH–CH3

Front 2353

Draw the structure from this splitting in proton NMR?

Back 2353

CH–(CH3)2

Front 2354

Give an example of protons not bonded to carbon atoms?

Back 2354

–OH (alcohols, carboxylic acids and phenols)
–NH (amines, amides and amino acids)

Front 2355

Describe the positions of –OH and –NH protons in protons NMR?

Back 2355

1. Form hydrogen bonds
2. Give broad NMR peaks of variable chemical shifts
3. Can occur at almost any chemical shift
4. Not usually involved in spin spin coupling
5. Makes assigning OH and NH protons difficult

Front 2356

What is the name of the technique used to identify –OH and –NH protons?

Back 2356

Proton exchange

Front 2357

What is proton exchange?

Back 2357

It is the process used to identify –OH and –NH protons

Front 2358

Describe the method of proton exchange?

Back 2358

1. Proton NMR spectrum is run as normal
2. A small volume of deuterium oxide D2O is added and the mixture is shaken before a second spectrum is run

Front 2359

Describe the theory of proton exchange?

Back 2359

Deuterium exchanges and replaces the OH and NH protons in the sample with deuterium atoms. As deuterium does not absorb in this chemica shift range, the OH peak disappears

Front 2360

Give the equation set up between methanol and deuterium oxide?

Back 2360

Front 2361

Back 2361

Front 2362

How are reaction rates measured?

Back 2362

By observing the changes in the quantities of reactants or products over time

Front 2363

What is the formula for the rate of reaction?

Back 2363

=quantity reactaed or produced/time

Front 2364

What is the unit of rate if time has been measured in seconds?

Back 2364

mol dm^–3 / s or mold dm^–3 s^–1

Front 2365

What are the units of concentration?

Back 2365

mol dm^–3

Front 2366

What does [A] mean?

Back 2366

Concentration of A

Front 2367

What is the order of a reaction?

Back 2367

The power to which the concentration of a reactant is raised in the rate equation

Front 2368

Define the overall order?

Back 2368

The sum of the individual orders if reactants in the rate equation

Front 2369

Describe the relationship between a reactant and its concentration?

Back 2369

The rate of reaction is proportional to the concentration of a particular reactant raised to a power

Front 2370

Name the first three orders?

Back 2370

Zero order (0)
First order (1)
Second order (2)

Front 2371

When is a reactant zero order?

Back 2371

When changing the concentration of a reactant has no effect on the rate of reaction

Front 2372

In a zero order reaction describe the effect an increase in concentration has on the rate if reaction?

Back 2372

It does not influence the rate

Front 2373

When is a reaction first order?

Back 2373

When the rate depends on its concentration raised to the power of one

Front 2374

In a first order reaction is the concentraion is...
1. Doubled
2. Trippled
What happens to the reaction rate?

Back 2374

1. It increaaes by a factor of 2
2. It increases by a factor of 3

Front 2375

When is a reaction second order?

Back 2375

When the rate depends on the concentration raised to the power of two

Front 2376

In a second order reaction when the the concentraion is...1. Doubled2. TrippledWhat happens to the reaction rate?

Back 2376

1. The reaction rate increases by a factor of 4
2. The reaction rate increases by a factor of 9

Front 2377

What does the rate equation give?

Back 2377

The mathematical relationship between the concentrations of the reactants and the reaction rate

Front 2378

What does the k represent in the rate eqution?

Back 2378

It is the rate constant. It is the number that mathenatically converts between the rate if reaction and conxentration and orders

Front 2379

What does the overall order give?

Back 2379

The overall effect of the concentrations of all reactants on the rate of reaction

Front 2380

Calculate the overall order for this rate equation?
Rate = k[A]^m[B]^n

Back 2380

M + n

Front 2381

Calculate the overall order for this rate equation?
Rate = k[A]^m[B]^n

Back 2381

M + n

Front 2382

How do you find the units of k in a rate equation?

Back 2382

1. Reaggarne the equation to make k the subjec
2. Substitute units into the experssion for k
3. Cancel common units and show the final units on a single line

Front 2383

What are the units for k in this rate equation. Rate = k[A]^0

Back 2383

dm^3 mol^–1 s^–1

Front 2384

What are the units of the rate constant k in the rate equation = k[A]^2[B]

Back 2384

dm^6 mol^–2 s^–1

Front 2385

How do you experimentally determine orders of reactions?

Back 2385

Experimentally by monitoring how a physical quantity changes over time

Front 2386

What can orders not be found from?

Back 2386

Chemical equations

Front 2387

What is the initial rate?

Back 2387

It is the instantaneous rate at the beginning of an experiment when t=0

Front 2388

What is continuous monitoring?

Back 2388

When continous measurements are taken during the course of a reaction

Front 2389

From what can you plot concentration–time graphs?

Back 2389

From the continuous measurements taken during the course of a reaction, this is called continuous moniorgin

Front 2390

Give two methods of continuous monitoring?

Back 2390

1. Monitoring by gas collection
2. Monitoring by mass lost

Front 2391

How do you do continous monitoring if a reaction dosent produce a gas?

Back 2391

Use another property that can be measured with time such as colour change

Front 2392

Give two methods in which colour change can be measured?

Back 2392

1. Eye
2. Colorimeter

Front 2393

Describe the basic principles of a colorimeter?

Back 2393

1. The wavelength of light passing through a coloured solution is controlled using a filter
2. The amount of lifht abosrobed by the solution is measured

Front 2394

What is recoreded by a colourimeter>

Back 2394

Absorbance, which is directly linked to the concentration of the solution

Front 2395

What filter is chosen in a colourimeter?

Back 2395

It is a complementary colour to the colour being absorbed in the reaction

Front 2396

Give the method of using a colourimeter?

Back 2396

1. Prepare standard solutions of the known concentration of the coloured chemical
2. Select a filter with the complementary colour to the chemical
3. Zero the colorimeter with water
4. measure the absorbance readings of the standard solutions
5. Plot a calibration curve of absorbance against concentration, you know have a way of calculating an absorbance reading
6. Carry out the reaction and take absorbance readings at measure time intertvals
7. Use the calibration curve to measure the concentration at each absorbance reading
8. Plot a graph of concentration against time

Front 2397

What can do determine from a concentration–time graph?

Back 2397

The order of reaction of the chemical for first and zero order reactions

Front 2398

What is the gradient of a concentration time graph?

Back 2398

It is the rate of the reaction

Front 2399

When can the order with respect to a reactant be obtained from a concentration time graph?

Back 2399

If the concentrations of all other reactants remain effectively constant

Front 2400

Describe the shape of a graph from a concentration–time graph of a zero order reaction?

Back 2400

A straight line with a negative gradient

Front 2401

What does a straight line with a negative gradient for a concentration–time graph show?

Back 2401

The reaction rate does not change during the course of the reaction.

Front 2402

What can be calculated from a straight line with a negative gradient for a concentration–time graph show?

Back 2402

The gradient is equal to the rate constant k.

Front 2403

What order is this?

Back 2403

Zero order

Front 2404

What order is this?

Back 2404

Zero order

Front 2405

Describe the curve produced on a concentration–time graph of a reaction that is first order?

Back 2405

A downward curve with a decreasing gradient over time

Front 2406

What does this graph show? (Quite literally describe the graph)

Back 2406

As the gradient decreases with time, the reaction gradually slows down.

Front 2407

What can be calculated from a downward curve with a decreasing gradient for a concentration–time graph show?

Back 2407

The half life as the time for the concentration to halve is constant. The rate constant of a first order reaction can be determined using its value

Front 2408

What order is a downward curve with a decreasing gradient over time in a concentration time graph?

Back 2408

First order

Front 2409

Draw a zero order concentration time graph?

Back 2409

Front 2410

Draw a first order concentration time graph?

Back 2410

Front 2411

What does a second order concentration time graph look like?

Back 2411

It is a downward curve, steeper at the start but tailing off more slowly

Front 2412

What is the symbol for half life?

Back 2412

t1/2

Front 2413

What is the half life?

Back 2413

It is the time taken for half of a reactant to be used up

Front 2414

Describe the half life of first order reactions?

Back 2414

They have a constant half life with the concentration halving every half life

Front 2415

What is exponential decay?

Back 2415

having a constant half life with the concentration halving every half life

Front 2416

having a constant half life with the concentration halving every half life is called.....

Back 2416

exponential decay

Front 2417

What are the two names of the methods used to determine k for a first order reaction?

Back 2417

1. Calcualting the rate constant from the rate
2. Calculating the rate constant from a half life

Front 2418

Describe how to calculate the rate constant from the rate in a concentration time graph?

Back 2418

1. Tangent to the curve is drawn
2. Gradient of the tangent is calculated as rate = gradient
3. The rate equation is re–arranged so that k= rate/concentration

Front 2419

Describe how to calculate the rate constant from the half life in a concentration time graph?

Back 2419

Use the exponential relationship for a constant half life

Front 2420

What is the exponential relationship between a constant half life and k?

Back 2420

k = ln2/t1/2

Front 2421

How do many drugs break down?

Back 2421

By exponential decay

Front 2422

Draw a zero order concentration–rate graph?

Back 2422

Front 2423

Draw a first order concentration–rate graph?

Back 2423

Front 2424

Draw a second order concentration–rate graph?

Back 2424

//fce-study.netdna-ssl.com/2/images/upload-flashcards/25/37/15/28253715_m.jpg

Front 2425

What order reaction is this rate–concentration graph?

Back 2425

Zero order

Front 2426

What order reaction is this rate–concentration graph?

Back 2426

first order

Front 2427

What order reaction is this rate–concentration graph?

Back 2427

second order

Front 2428

Describe the shape of a zero order rate–concentration graph?

Back 2428

A horizontal straight line with a zero gradient

Front 2429

Describe the shape of a first order rate–concentration graph?

Back 2429

A straight line graph through the origin

Front 2430

Describe the shape of a second order rate–concentration graph?

Back 2430

An upward curvewith increasing gradient

Front 2431

What info can you get from this graph about the reaction in terms of maths?

Back 2431

rate = k[A]^0 so rate=k

1. The intercept of the y axis gives the rate constant k

2. The reaction rate does not change with increasing concentration

Front 2432

What info can you get from this graph about the reaction in terms of maths?

Back 2432

rate = k[A]^1 so rate=k[A]

1. The rate is directly proportional to the concentration. This means the gradient gives the rate constant

2. The rate constant can be determined by measuring the gradient of the straight line of the graph

Front 2433

What info can you get from this graph about the reaction in terms of maths?

Back 2433

Second order so rate = k[A]^2

1. Because this is a curve the rate constant cannot be determined

2. If you plot the rate against the concentration squared you get a straight line, from this the rate constant can be calculated as the gradient

Front 2434

What is the initial rate?

Back 2434

It is the instantaneous rate at the start of a reaction when the time=0. This is found by measuring the gradient of a tangent drawn at t=0 on a concentration–time graph

Front 2435

What is a clock reaction?

Back 2435

A way of obtaining the inital rate of a reaction by taking a single measurement

Front 2436

Describe the method for a clock reaction?

Back 2436

1. The solution is colourless at the start
2. The time taken, once the reactants are mixed, for the cross under the flask to appear is measured
3. The rate is proportional to 1/t

Front 2437

In a clock reaction what is rate proportional too?

Back 2437

1/T

Front 2438

Why in a clock reaction is the inital rate proportional to 1/T

Back 2438

Because there will be no significant change in rate during this time so the average rate of reaction over this time will be the same as the initial rate

Front 2439

Describe the accurcay of a clock reaction?

Back 2439

It is approximatley accurate provoded that less than 15% of the reaction has taken place

Front 2440

What are you measuring in a clock reaction?

Back 2440

The average rate during the first part of the reaction

Front 2441

When can a reaction take place? (Movement of particles)

What is the problem with this? (Think of reaction mechanisms)

Back 2441

When particles collide
Sometimes more than two molecules/ions would have to collide simultaneously which is extremely unlikely

Front 2442

Sometimes for a reaction to occur more than two molecules/ions would have to collide simultaneously which is extremely unlikely... how is this overcome?

Back 2442

The reaction occurs in a series of steps so it is unlikely that more than two particles will collide together at the same time

Front 2443

What is the reaction mechanism? Physical chemistry

Back 2443

The series of steps that make up an overall reaction

Front 2444

What are the steps that make up an overall reaction called?

Back 2444

The reaction mechanism

Front 2445

What is the rate determining step?

Back 2445

The slowest step in a reaction mechanism

Front 2446

What is the slowest step in a reaction mechanism called>

Back 2446

The rate determining step

Front 2447

How do you know whether a reaction mechanism is likely to be correct?

Back 2447

1. The rate equation only includes reacting specieis involved in the rate–determining step
2. The orders in the rate equation match the number of species involved in the rate–determining step

Front 2448

Give the ionic equation of haloalkanes being hydrolused by alkaili?

Back 2448

RBr + OH^– ––> ROH + Br^–

Front 2449

What hydrolyses haloalkanes?

Back 2449

Hot aqueous alkali

Front 2450

Describe how temperature effects the rate of reaction?

Back 2450

1. Increasing the temperature increases the proportion of particles that exceed the activation energy
2. As the temperature increases, particles move faster and collide more frequently

Front 2451

With increase in temperature describe the ratio between the increased frequency of collision and the activation energy?

Back 2451

The increased frequency of collisions is small compared with the molecules that exceed the activation energy, therefore the change in rate is mainly determined by the activation energy

Front 2452

Give arrhenius equation?

Back 2452

k= A e^–Ea/RT

Front 2453

What is the name given to the equation that links temperature, activatuon and the rate constant?

Back 2453

The arrhenius equation

Front 2454

What does the 'A' represent in arrhenius equation?

Back 2454

The pre–expoinential factor, the y intercept. This takes into account the frequency of collisions with the correct orientation

Front 2455

What does the 'e^–Ea/RT' represent in the arrhenius equation?

Back 2455

The exponential factor linked to activation energy and temperature; therefore the proportion of molecules that exceed Ea and that have sufficient energy for a reaction to take place

Front 2456

What are the units of these in the arrhenius equation?
k
R
A
Ea
T

Back 2456

k = depends on the order of reaction
R = J mol^–1 K^–1
A = constant so no units
Ea = KJ mol^–1
T = K

Front 2457

Describe A in the arrhenius equation as temperature increases?

Back 2457

It does increase slightly with temperature as the frequency of collisions increases but is essentially constant over a small temperature range.

Front 2458

Give the logarithmic form of the arrhenius equation?

Back 2458

ln k = – Ea/RT + lnA

Front 2459

A plot of .... against .... gives a straight line graph of the type y = mx +c


Arrjenius equation

Back 2459

ln k against 1/T

Front 2460

Equate the log form of arrhenius equation with y = mx + c

Back 2460

ln k = – Ea/R times 1/T + lnA


y = m times x + c

Front 2461

In a graph of ln k against 1/T which goes on each axis?

Back 2461

1/T goes on the x axis


ln k goes on the y axis

Front 2462

How do you calculate the activation energy from a graph of ln k against 1/T?

Back 2462

Caulculate the gradient of the line, this is the activation energy over the gas constant divided by 1000 (because the gas constants has units of joules)

Front 2463

How do you work out A from a graph of ln k against 1/T?

Back 2463

Extrapolate back to the y axis, find the inverse of ln using e.


Or use the equation y=mx+c

Front 2464

Write Kc

Back 2464

Front 2465

Give the equation for Kc?

Back 2465

Front 2466

Give kc equation?

Back 2466

Front 2467

The larger the value of Kc....

Back 2467

... the further the position of the equilibrium towards the products

Front 2468

Caluclate the units of Kc for this equation?

Back 2468

Front 2469

What are the two types of equilibria?

Back 2469

1. Homogenous
2. Heterogenous

Front 2470

Define a homogenous equilibria?

Back 2470

Equilibrium that contains species that all have the same state or phase

Front 2471

Is this equilibria homogenous or heterogenous?

Back 2471

Homogenous

Front 2472

Is this equilibria homogenous or heterogenous?

Back 2472

Homogenous

Front 2473

Is this equilibria homogenous or heterogenous?

Back 2473

Homogenous

Front 2474

Is this equilibria homogenous or heterogenous?

Back 2474

Heterogenous

Front 2475

Is this equilibria homogenous or heterogenous?

Back 2475

Heterogenous

Front 2476

Is this equilibria homogenous or heterogenous?

Back 2476

Heterogenous

Front 2477

Define a heterogenous equilbrium?

Back 2477

It is a equilibrium that have different states or phases.

Front 2478

Answer me... remember units!

Back 2478

45 dm^3 mol^–1

Front 2479

How is equilbria involving gases expressed?

Back 2479

In terms of Kp

Front 2480

What is Kp? Give the formula

Back 2480

The equilibrium in terms of partial pressure Kp=(C)^c(D)^d/(A)^a(B)^b

Front 2481

Define Kc?

Back 2481

Kc is an equilibrium constant in terms of molar concentrations Kc=[C]^c[D]^d/[A]^a[B]^b

Front 2482

What is the mole fraction of a gas?

Back 2482

It is its proportion by volume to the total volume of gases in a gas mixture

Front 2483

Give the equation for mole fraction?

Back 2483

= number of moles/total number of moles in gas mixture

Front 2484

Define partial pressure?

Back 2484

It is the contribution that the gas makes towards the total pressure

Front 2485

What is the equation for partial pressure?

Back 2485

= mole fraction x total pressure

Front 2486

What are suitable units for Kp?

Back 2486

kPa, Pa or atm

Front 2487

What species does Kp include?


Why?

Back 2487

Only gases


Only gases have partial pressures so other species must be ignored

Front 2488

What are the three rules with the reagrds to concentration, pressure and temperature and equilibrium position shift?

Back 2488

1. If the concentration of a species is increased, the equilibrium position shifts in the direction that reduces the concentration
2. If the pressure is increased, the equilibrium position shifts towards the side with fewer gaseous moles
3. If the temperature is increased, the equilibrium position shifts in the endothermic direction

Front 2489

What does K=1 mean in terms of equilibrium?

Back 2489

It indicates an equilibrium halfway between the reactants and products

Front 2490

What does k =100 in terms of equilibrium?

Back 2490

It indicates an equilibrium in favour of the products

Front 2491

What does k= 1x 10^ –2 mean in terms of equilibrium?

Back 2491

An equilibrium in favour of the reactants

Front 2492

At a set temperature what is K like?

Back 2492

It is constant

Front 2493

What happens to the value of K in equilibria when the concentration is changed?

Back 2493

Nothing – only temperature effects K

Front 2494

What happens to the value of K in equilibria when the pressure is changed?

Back 2494

Nothing – only temperature effects K

Front 2495

What happens to the value of K in equilibria when a catalyst is added?

Back 2495

Nothing – only temperature effects K

Front 2496

What happens to the value of K in equilibria when the temperature is changed?

Back 2496

It causes the value of K to change value

Front 2497

What happens to the value of the equilibrium constant if the temperature is increased and the forward reaction is exothermic?

Back 2497

1. Raising the temperature decreases the equilibrium yield of products
2. Equilibrium constant decreases with increasing temperature

Front 2498

What happens to the value of the equilibrium constant if the temperature is increased and the forward reaction is endothermic?

Back 2498

1. Rasing the temperature increases the equilibrium yield of products
2. The equilibrium constant increases with increasing temperature

Front 2499

In Kp, if the forward reaction is exothermic, what happens to the partial pressure of the products/reacants if the temperature is increased?

Back 2499

The pp of the products must decrease and the partial pressures of the reactants must increase

Front 2500

In Kp, if the forward reaction is endothermic, what happens to the partial pressure of the products/reactants when temp is increased?

Back 2500

1. Partial pressure of the products must increase
2. Partial pressures of the reactants myst decrease

Front 2501

Describe why concentration does not change the Kc value at equilibrium but le Chateliers principle says that the equilibrium position can be shifted by changes in concentration?

Describe when concentration of reactants is increased

Back 2501

1. Concentration of reactants is increased
2. The system is no longer in equilibrium becaause the katio is now less than Kc
3. The concentrations must change to return the ratio back to the Kc value
4. The concentrations of the products must increase
5. Concentrations of the reactants must decrease
6. Shift of the position of equilibrium to the right

Front 2502

Describe why doubling the pressure does not change the K value at equilibrium but leChatelier's principle says that the equilibrium position can be shifted by doubling the pressure?

N2O4 ––> 2NO2

Back 2502

1. If the total pressure is doubled the partial pressure is doubled
2. The ratio is now greater than Kp (as two moles on the right)
3. The system is no longer in equilibrium
4. The partial pressure of the product must decrease
5. The partial pressure of the reactant must increase
6. Position of equilibrium shifts to the left

Front 2503

What happens to partial pressure and concentrations of the reacants/products in equilibrium when the pressure is doubled?

Back 2503

The partial pressure is doubled
The concentration is doubled

Front 2504

What part of a chemical reaction does a catalyst affect?

Back 2504

The rate of a chemical reaction as it speeds up both the forward and reverse reaction by the same factor

Front 2505

What is the arrhenius model of acids?

Back 2505

Acids dissociate and release H^+ ions in aqueous solution

Front 2506

What is the arrhenius model of bases?

Back 2506

Alkalis dissociate and release OH^– ions in aqueous solution

Front 2507

What was the earliest idea of acids and alkalis?

Back 2507

Acids are sour
Alkalis are from plant ashes

Front 2508

What is the model of acids/bases that replaced Arrhenius?

Back 2508

The Bronsted–Lowry model

Front 2509

What is the Bronsted–Lowry model of acids?

Back 2509

It is a proton donor

Front 2510

What is the Bronsted–Lowry model of bases?

Back 2510

A proton acceptor

Front 2511

What does a single arrow in an equation represent?

Back 2511

That the reaction goes to completion

Front 2512

What is a conjugate acid–base pair?

Back 2512

It is a pair that contains two species that can be interconverted by a transfer of a proton

Front 2513

What is the conjugate base of HCl?

Back 2513

Cl^–

Front 2514

What is the conjugate acid of Cl^–?

Back 2514

HCl

Front 2515

Label the conjugate acid/base pairs?

Back 2515

Front 2516

Label the conjugate acid/base pairs?

Back 2516

Front 2517

What is this ion called; H3O^+?

Back 2517

The Hydronium ion

Front 2518

What is the conjugate acid of water?

Back 2518

H3O^+

Front 2519

Why is the hydronium ion important?

Back 2519

It is the active acid ingrediant in any aqeuous acid

Front 2520

What is the more complex version of this equation?


H^+ + OH^– ––> H2O

Back 2520

H3O^+ + OH^– ––> 2H2O

Front 2521

What do the temrs monobasic, dibasic and tribasic acids refer to?

Back 2521

The total number of hydrogen ions in the acid that can be replaced per molecule in an acid–base reaction

Front 2522

Is HCl monobasic, dibasic or tribasic?

Back 2522

Monobasic

Front 2523

Is CH3COOH monobasic, dibasic or tribasic?

Back 2523

monobasic

Front 2524

Is H2CO3 monobasic, dibasic or tribasic?

Back 2524

dibasic

Front 2525

Is H3BO3 monobasic, dibasic or tribasic?

Back 2525

tribasic

Front 2526

What is the active species from acid?

Back 2526

H^+

Front 2527

What are spectator ions?

Back 2527

They are ions that do not change during the reaction

Front 2528

Who introduced pH on a simple numerical scale?

Back 2528

Soren Sorensen

Front 2529

Why is the pH scale that soren sorenson introduced more simple?

Back 2529

It dosent deal with numbers of power to the minus 10 and so the pH values are more manageable as they are whole numbers

Front 2530

For any solution at 25 degrees what does each of these show:
1. pH less than 7
2. pH greater than 7
3. pH 7

Back 2530

1. Decreasing acidity
2. Increasing alkalinity
3. Neutral

Front 2531

Before soren sorensens pH scale, how was the degree of alkalinity measured?

Back 2531

Using colour

Front 2532

Before soren sorensens pH scale the degree of alkalinity was measured using colour. How did Sorenson tie the two together?

Back 2532

He gave numbers to the colours

Front 2533

How is pH measured accurtaley these days?

Back 2533

Using a pH meter

Front 2534

A low value of [H^+(aq)] means....

Back 2534

a high value of pH

Front 2535

A high value of [H^+(aq)] means....

Back 2535

a low value of pH

Front 2536

What is the mathematical relationship between pH and [H^+(aq)] ?

Back 2536

Front 2537

How do you calculate [H^+] from the mathematical relationship between pH and [H^+(aq)] ?

Back 2537

Front 2538

How much of a differnece is there between a pH of 2 and 3?

Back 2538

A change of one pH number is equal to a 10 times difference so there is a large difference in hydrogen ion concentration

Front 2539

What factor difference is there between a solution of pH of 1 and a pH of 2?

Back 2539

10 times

Front 2540

How do you dilute a solution from pH 1 to pH 4? (what factor dilution)

Back 2540

Dilute it by 1000 times

Front 2541

What happens to a strong monobasic acid in solution (HA)?

Back 2541

It completely dissociates

Front 2542

As a strong monobasic acid completley dissociates in solution... what can be said about the concentration of the H^+ ions produced?


Therefore what can be calculated?

Back 2542

It is equal to the concentration of the acid so the pH of a strong acid can be calculated directly from the concentration of the acid

Front 2543

What are the terms strong and weak acids used to describe?

Back 2543

The extent of dissociation of an acid

Front 2544

Describe what happens to a weak acid in solution?

Back 2544

It partially dissociates

Front 2545

What constant is used to measure the extent of dissociation of a weak acid?

Back 2545

Ka; the acid dissociation constant

Front 2546

Give the expression for Ka?

Back 2546

Front 2547

What is the problem with Ka?


Therefore what happens?

Back 2547

It is difficult to compare numbers with negative indicies.


The Ka value has been converted into a negative logarithm called pKa

Front 2548

Give the expression of pKa? (Not Kp)

Back 2548

Front 2549

How do you calculate Ka from pka?

Back 2549

Ka = 10^ –pKa

Front 2550

The stronger the acid...
1. What happens to Ka
2. What happens to pKa?

Back 2550

1. The larger the value2. The smaller the value

Front 2551

The weaker the acid...
1. What happens to Ka
2. What happens to pKa?

Back 2551

1. The smaller the Ka value
2. The larger the pKa value

Front 2552

What two things does the concentration of [H^+(aq)] depend upon for a weak acid?

Back 2552

1. The concentration of the acid
2. The acid dissociation constant Ka

Front 2553

What are the approximations made in terms of Ka?

Back 2553

1. HA dissociates to produce equal concentrations of H^+ and A^– and the dissociation of water is so small it can be neglected [H^+(aq)] = [A^–(aq)]
2. The equilibrium concentration of HA is equal to the start concentration as the dissociation of weak acids is small [HA(aq)]eqm = [HA(aq)]start

Front 2554

Give the simplified Ka expression?

Back 2554

Ka = [H^+(aq)]eqm^2/[HA(aq)]start

Front 2555

How can Ka for a weak acid be determined experimentally?

Back 2555

1. Preparing a standard solution of the weak acid of known concentration
2. Measuring the pH of the standard solution using a pH meter

Front 2556

The first approximation of Ka is:
HA dissociates to produce equal concentrations of H^+ and A^– and the dissociation of water is so small it can be neglected [H^+(aq)] = [A^–(aq)]


What is the weakness in this?

Back 2556

If the pH>6 then [H^+(aq)] from the dissociation of water will be significant compared with dissociation of the weak acid so the approximation breaks down for very weak acids or dilute solutions

Front 2557

The second approximation of Ka is:
The equilibrium concentration of HA is equal to the start concentration as the dissociation of weak acids is small [HA(aq)]eqm = [HA(aq)]start



What is the weakness in this?

Back 2557

It breaks down when [H^+(aq)] is significant and there is a real difference between [HA(aq)]eqm and [HA(aq)]start. Therefore the approximation is not justified for stronger weak acids.

Front 2558

Give the acid base equilibrium of water?

Back 2558

H2O + H2O –> H3O^+ + OH^–

Front 2559

To what extent does water dissociate?

Back 2559

1 dm^3 of water is mainly undissociated H2O

Front 2560

What is Kw?

Back 2560

It is the ionic product of water – the ions in water multipled together

Front 2561

GIve the equation for Kw?

Back 2561

Front 2562

Describe when Kw changes?

Back 2562

It varies with temperature (as do all equlibrium constants)

Front 2563

What is the significance of Kw having a value of 1.00 x 10^14 at 25 degrees?

Back 2563

It sets up the neutral point in the pH scale. And therefore Kw controls the concentration of H^+ and OH^– ions

Front 2564

Why, on dissociation is water neutral?


Therefore what equation can be derived?

Back 2564

It produces the same number of H6+ and OH^– ions


[H^+ (aq)] = [OH^–(aq)]

Front 2565

Calucate the pH when Kw = 1.00 x 10^–14

Back 2565

[H^+ (aq)] = [OH^–(aq)]


Kw= [H^+ (aq)]^2


[H^+ (aq)] = root 1.00 x 10^–14

= 1.00 x 10^–7


pH = –log[H^+ (aq)] = 7

Front 2566

In an aqeuous solution what ions will definitely be present?

Back 2566

H^+ and OH^– ions

Front 2567

When is a solution acidic? (equation)

Back 2567

[H^+ (aq)] > [OH^–(aq)]

Front 2568

When is a solution neutral? (equation)

Back 2568

[H^+ (aq)] =[OH^–(aq)]

Front 2569

When is a solution alkaline? (equation)

Back 2569

[H^+ (aq)] < [OH^–(aq)]

Front 2570

What is a strong base?

Back 2570

An alkali that completley dissociates in solution

Front 2571

How can the pH of a strong base be calculated?

Back 2571

1. The concentration of the base
2. The ionic product of water

Front 2572

Give an example of a weak base?

Back 2572

Ammonia gas as it releases OH^– ions in water

Front 2573

Define a buffer solution?

Back 2573

It is a system that minimises pH changes when small amounts of an acid or a base is added

Front 2574

What are the two components of a buffer solution and what do they do?

Back 2574

1. A weak acid, HA which removes added alkali
2. Its conjugate base A^– which removes added acid

Front 2575

When does a buffer solution lose its buffering ability?

Back 2575

When one of the two components in the buffer solution has reacted and been used up it loses its buffering ability

Front 2576

Describe whether the pH remains completley constant in a buffer solution when acid or alkali are added?

Back 2576

The pH does change but only by a small amount. The pH does not stay completely constant

Front 2577

What are the two ways of preparing a weak acid buffer solution?

Back 2577

1. Preparation from a weak acid and its salt
2. Preparation by partial neutralisation of the weak acid

Front 2578

How is a weak acid buffer solution prepared from a weak acid and its salt (use specific chemical examples)?

Back 2578

By mixing a solution of ethanoic acid with one of its salts such as sodium ethanoate

Front 2579

What happens when ethanoic acid is added to water?

Back 2579

It partially dissociates and the amount of ethanoate ions in solution is very small

Front 2580

By mixing a solution of ethanoic acid with one of its salts such as sodium ethanoate a weak acid buffer system is generated.

Give the equations to show these two components?

Back 2580

Component 1: CH3COOH
CH3COOH <––> H^+ + CH3COO^–


Component 2: CH3COO^–

CH3COONa +aq ––> CH3COO^– + Na^+

Front 2581

Why in preparation of a weak acid buffer solution is it prepared from a weak acid and its salt?

Back 2581

Weak acids only partially dissociate in water. Therefore whilst there is lots of the acid component, there is not much of its conjgate base. The salt has to be added to increase the concentration of its conjugate base which reacts to neutralise acid in solution.

Front 2582

What do salts of weak acids provide in buffer solutions?

Back 2582

A source of the conjugate base

Front 2583

Describe the dissociation of salts in aq solution?

Back 2583

It is complete

Front 2584

How can a weak acid buffer solution be prepared by partial neutralisation?

Back 2584

1. Add an aqueous solution of an alkali to an excess of the weak acid
2. The weak acid is partially neutralised by the alkali forming the conjugate base
3. Some of the weak acid is left over unreacted
4. The resulting mixture of the salt of the weak acid and any unreacted weal acid

Front 2585

Describe how in the ethanoic acid equilibrium the CH3COOH and CH3COO^– are able to act independently to remove added acid and alkali?

Back 2585

By shifting the buffers equilibrium either to the left or to the right.
CH3COOH ––> H^+ + CH3COO^– (with added CH3COO^– ions)
When further CH3COO^– ions are added to the CH3COOH the equilibrium position shifts even further to the left, reducing the small concentration of H^+ ions

Front 2586

On addition of an acid to a buffer solution, what happens?

Back 2586

1. [H^+ (aq)] increases as acid concentration increases
2. H^+ ions react with the conjugate base A^–
3. The equilibrium position shifts to the left, removing most of the H^+ ions

Front 2587

On addition of an alkali to a buffer solution, what happens?

Back 2587

1. [OH^– (aq)] increases
2. The small concentration of H^+ ions reacts with the OH^– ions: H^+ + OH^– ––> H2O
3. Because H^+ ions have been removed HA dissociates, shifting the equilibrium position to the right to restore most of the H^+ ions

Front 2588

Why do you need to consider which acid to use in a buffer solution?

Back 2588

Different weak acids result in buffer solutions that operate over different pH ranges

Front 2589

When is a buffer most effective at removing either added acid or alkali?

Back 2589

When there are equal concentrations of the weak acid and its conjugate base

Front 2590

What are two properties of a buffer when [HA] = [A^–]?

Back 2590

1. The pH of the buffer solution is the same as the pKa value of HA
2. The operating pH is typically over about two pH units, centered at the pH of the pKa value

Front 2591

Why when [HA] = [A^–] is the pH of the buffer solution the same as the pKa value of HA?

Back 2591

Ka = [H^+]^2/[HA]
pKa = –log([H^+]^2/[HA])


Ka = [H^+][A^–]/[HA]
[H^+] = Ka[HA]/[A^–] but HA = A^– so
[H^+] = Ka

–log[H^+] = –log(Ka) so
pH = pKa

Front 2592

What assumption of the dissociation of weak acids no longer applies to buffer solutions and why?

Back 2592

[H^+] = [A^–]
For a buffer solution this is no longer true at A^– has been added as one of the components of the buffer

Front 2593

What is the equation for the pH of a buffer solution from Ka?

Back 2593

[H^+] = ka x [HA]/[A^–]

–log(ka x [HA]/[A^–])

Front 2594

Give an example of a buffer solution in a living system?

Back 2594

In the human body a buffer solution is used to maintain blood pH at 7.40

Front 2595

What pH does the blood plasma need to be maintained at?


Therefore what is the pH of normal healthy blood?

Back 2595

7.35 and 7.45


7.40

Front 2596

What is the buffer solution that controls pH of blood?

Back 2596

The carbonic acid–hydrogencarbonate (H2CO3/HCO3^–) buffer system

Front 2597

What happens to a person if the blood pH falls below 7.35?

Back 2597

People can develop a condition called acidosis which can cause fatigue, shortness of breath and in extreme cases, shock or death

Front 2598

What happens to a person if their blood pH rises above 7.45?

Back 2598

People develop a condition called alkalosis which can cause muscle spasms, light–headedness and nausea

Front 2599

What happens in the blood in the addition of an acid? (In regards to the buffer system)

Back 2599

1. [H^+] increases
2. H^+ ions react with the conjugate base HCO3^–
3. The equilibrium position shifts to the left, removing most of the H^+ ions

Front 2600

What happens in the blood on the addition of an alkali?

Back 2600

1. [OH^–] increases 2. H^+ ions react with the OH^– ions: H^+ + OH^– ––> H2O
3. H2CO3 dissociates, shifting the equilibrium position to the right to restore most of the H^+ ions

Front 2601

Does the body produce more acidic or alkaline materials?


What does this cause to build up in the blood?

Back 2601

Acidic


H2CO3 as lots of the HCO3^– has been converted by reaction which hydrogen ions

Front 2602

What happens to the H2CO3 which builds up in the blood?

Back 2602

The body converts it to carbon dioxide gas which is then exhaled by the lungs

Front 2603

What can be used to monitor neutralisation reactions?

Back 2603

Indicators

Front 2604

What is a pH meter?

Back 2604

It is an electrode that is dipped into a solution and connected to a meter that displays the pH reading. A pH reading typically records pH values to 2dp.

Front 2605

Why is a pH meter better than indicator paper?

Back 2605

Indicator paper is usually matched from colour charts to the nearest whole number so a pH meter is able to give more accurate measurements of pH during a titraction

Front 2606

Give the method of using a pH meter when an aqueous base is added to an acid solution in a titration?

Back 2606

1. Using a pipette add a measured volume of acid to a conical flak
2. Place the electrode of the pH meter in the flask
3. Add aqueous base to the burette and add to the acid in the conical flask 1 cm^3 at a time
4. After each addition, swirl the contents. Record the pH and the total volume of aqueous base added
5. Repeat steps 3 and 4 until the pH starts to change more rapidly. then add the aqueous base dropwise for each reading until the pH changes less rapidly

Front 2607

Draw and label the key features of a typical pH titration curve where the base is being added to the acid

Back 2607

Front 2608

Describe what is happening at each stage of this graph?

Back 2608

1. When the base is first added the acid is in great excess and the pH increases very slightly

2. As the vertical section is approached, the pH starts to increase more quickly as the acid is used up ore quickly

3. The pH increases rapidly during addition of a very small volume of base, producing the vertical section

4. After the vertical section, the pH will rise very slightly as the base is now in great excess

Front 2609

What is the equivalence point of a titration?

Back 2609

It is the volume of one solution that exactly reacts with the volume of the other solution

Front 2610

Where is the equivilence point on a pH titration curve?

Back 2610

It is the center of the vertical section of the pH curve

Front 2611

What is an acid–base indicator>

Back 2611

It is a weak acid HA that has a distinctively different colour from its conjugate base A^–

Front 2612

Give the colours of methyl orange?

Back 2612

1. The weak acid HA is red
2. The conjugate base A^– is yellow
3. At the end point it is orange

Front 2613

Define the end point of a titration?

Back 2613

the point in a titration at which a reaction is complete, often marked by a colour change.

Front 2614

Describe the state of the acid–base indicator at the end point of a pH titration?

Back 2614

The indicator contains equal concentrations of HA and A^– and the colour will be in between the two extremes

Front 2615

Give the colour of methyl orange at its end point and explain why?

Back 2615

The indicator contains equal concentrations of HA and A^– and the colour will be in between the two extremes of red and yellow; it is orange

Front 2616

In acidic conditions where is the position of equilibrium of the acid–base indicator?

Back 2616

It is shifted towards the weak acid

Front 2617

In basic conditions where is the position of equilibrium of the acid–base indicator?

Back 2617

It is shifted towards the conjugate base

Front 2618

On addition of a basic solution to an acid in a titration, what happens to the acid–base indicator methyl orange?

Back 2618

1. OH^– ions react with H^+ in the indicator; H^+ + OH^– ––> H2O
2. The weak acid, HA dissociates to replace the lost H^+ ions, shifting the equilibrium position to the right
3. The colour changes first to orange at the end point and finally to yellow as the equilibrium position is shifted to the right

Front 2619

On addition of an acid solution to a basic solution in a titration, what happens to the acid–base indicator methyl orange?

Back 2619

1. H^+ ions react with the conjugate base A^–
2. The equilibrium position shifts to the left
3. The colour changes, first to orange at the end point and finally to red when the equilibrium position has shifted to the left

Front 2620

Why do different indicators change colour over different pH ranges?

Back 2620

They have different Ka values

Front 2621

What two things about the indicator are true at the end point of a titration?

Back 2621

[HA] = [A^–]
so pKa = pH

Front 2622

What does the sensitivity of an indicator depend upon?

Back 2622

1. The indicator itself
2. Eyesight

Front 2623

What range do indicators usually change colour over?

Back 2623

About two pH units

Front 2624

How must you chose an indicator for a pH titration curve?

Back 2624

The indicators colour change must coincide with the vertical section of the curve

Front 2625

What ideally must be the same with an indicator in a pH titration curve?

Back 2625

The end point and the equivalence point would coincide

Front 2626

Which indicator is suitable for a weak acid–weak base titration?

Back 2626

None, as there is no vertical section and even at its steepest, the pH requires several cm^3 to pass through a typical pH indicator range

Front 2627

Draw a graph of a strong acid and strong base pH titration curve?

Back 2627

Front 2628

Draw a graph of a strong acid and weak base pH titration curve when adding the base to the acid?

Back 2628

Front 2629

Draw a graph of a weak acid and strong base pH titration curve?

Back 2629

Front 2630

Draw a graph of a weak acid and weak base pH titration curve?

Back 2630

Front 2631

Describe the stability of solid ionic compounds?

Back 2631

They are very stable because of the strength of the ionic bonds (electrostatic attractions between oppositely charged ions in the ionic lattice structure)

Front 2632

Why do ionic compounds have high melting points?

Back 2632

They are very stable due to the ionic bonds. This creates a substantial energy barrier that must be overcome to break down the lattice

Front 2633

Define lattice enthalpy?

Back 2633

Lattice enthalpy is a measure of the strength of ionic bonding in a giant ionic lattice. It is the enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

Front 2634

What enthalpy change is this?

Back 2634

Lattice enthalpy

Front 2635

What is the symbol for the lattice enthalpy

Back 2635

Front 2636

What sign is the lattice enthalpy? +ve or –ve why?

Back 2636

It an exothermic change and will always be negative because it involves bond formations from seperate gaseous ions

Front 2637

How do you calculate lattice enthalpy?

Back 2637

As it cannot be measured directly it must be calculated indirectly using known energy changes in an energy cycles called a Born–Haber cycle

Front 2638

Label this diagram starting with the yellow box in the top right and working clockwise

Back 2638

1. Gaseous ions

2. Lattice enthalpy

3. Ionic Lattice

4. Lattice formation from elements

5. Elements in standard states

6. Formation of gaseous atoms

7. Gaseous atoms

8. Formation of gaseous ions

Front 2639

Describe the stages of route 1 of the born–haber cycle?

Back 2639

1. Formation of gaseous atoms; changing the elements in their standard states into gaseous atoms, this change is endothermic as it involves bond breaking

2. Formation of gaseous ions; changing the gaseous atoms into positive and negative gaseous ions, overall this change is endothermic

3. Lattice formation; changing the gaseous ions into the solid ionic lattice, this is the lattice enthalpy and is exothermic

Front 2640

Describe the stages of route 2 of the born–haber cycle?

Back 2640

The elements in their standard states are converted directly to the ionic lattice. There is just one enthalpy change, the enthalpy change of formation which is exothermic

Front 2641

Define the standard enthalpy change of atomisation?

Back 2641

It is the enthalpy change that takes place for the formation of one mole of gaseous atoms from the element in its standard state under standard conditions

Front 2642

Give the symbol for the standard enthalpy change of atomisation?

Back 2642

Front 2643

Give the equation for the standard enthalpy change of atomisation for sodium?

Back 2643

Front 2644

Give the equation for the standard enthalpy change of atomisation for chlorine?

Back 2644

Front 2645

What sign (+ve/–Ve) is the standard enthalpy change of atomisation?

Back 2645

It is an endothermic process because bonds are being broek nto form gaseous atoms

Front 2646

When the element if a gas in its standard state, what is the enthalpy of atomisation related to?

Back 2646

The bond enthalpy of the bond being borken

Front 2647

For Cl2 (g) ––> 2Cl(g) +242 kJmol^–1


What is the enthalpy of atomisation?

Back 2647

121 kJmol^–1

Front 2648

What sign (+ve/–Ve) are ionisation energies?

Back 2648

They are endothermic because energy is required to overcome the attraction between a negative electron and the positive nucleus

Front 2649

What is electron affinity? Not enthalpy definition

Back 2649

It is the opposite of ionisation energy, it measures the energy to gain electrons

Front 2650

Why is electron affinity the opposite of ionisation energy?

Back 2650

Electron affinity measures the energy to gain electrons, ionisation energy measures the energy to lose electrons

Front 2651

Define the first electron affinity?

Back 2651

It is the enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form one mole of gaseous 1– ions

Front 2652

What is the symbol for the first ionisation energy?

Back 2652

Front 2653

What is the symbol for the first electron affinity?

Back 2653

Front 2654

What sign (+ve/–Ve) are first electron affinities?
Why?

Back 2654

Exothermic becauase the electron being added is attracted in towards the nucleus

Front 2655

Answer me!

Back 2655

= –790 kJmol^–1

Front 2656

Answer me!

Back 2656

= –2528 kJmol^–1

Front 2657

Give the equations for the first two electron affinities for oxygen?

Back 2657

Front 2658

What sign (+ve/–Ve) are second electron affinities?Why?

Back 2658

They are endothermic. A second electron is being gained by a negative ion which repels the electron away so energy must be put in to force the negativaly charged electron onto the negatively charged ion

Front 2659

Draw a diagram showing the energy changes for formation of O^2–?

Back 2659

Front 2660

Define the standard enthalpy change of solution?

Back 2660

It is the enthalpy change that takes place when one mole of a solute dissolves in a solvent

Front 2661

What is the symbol for the standard enthalpy change of solution?

Back 2661

Front 2662

What is the overall enthalpy change associated with the dissolving process?

Back 2662

The enthalpy change of solution

Front 2663

Give the equation for the enthalpy change of solution of sodium chloride?

Back 2663

Front 2664

What does the + aq represent in this?

Back 2664

An excess of water

Front 2665

If the solvent in water, what does the finish dissolved ionic lattice look like? (brief not detailed)


Describe the directions of attraction?

Back 2665

The ions from the ionic lattice finish up surrounded with water molecules as aqueous ions


It exists in three dimensions

Front 2666

Is the enthapy change of solution exothermic or endothermic?

Back 2666

It can be either

Front 2667

Describe the difference in attractions between NaCl (s) and NaCl (aq)?

Back 2667

NaCl (s); Na^+ and Cl^– ions attracted together in a giant ionic lattice
NaCl (aq); Na^+ and Cl^– ions are separated but now surrounded by water molecules

Front 2668

Describe the attractions (detailed) between NaCl ions and water when it dissolves?

Back 2668

1. The delta negative oxygen is attracted to the positive sodium ion
2. The delta positive hydrogen atom is attracted to the negative chloride ion

Front 2669

Draw the resulting solution when this ionic compound dissolves. Draw one molecule of each ion formed

Back 2669

Front 2670

Describe the method for the experimental determination of the enthalpy change of solution of KCl?

Back 2670

1. Weigh out sample of KCl
2. Pour 25cm^3 of distilled water into a plastic cup in a beaker. Measure the temperature of the water
3. Quickly tip of KCl into the water in the plastic cup. Stir the mixture with the thermometer until all of the KCl has dissolved and the temperature no longer changes, record this temperature

Front 2671

How do you calcuate the enthalpy change of solution from an experiment?

Back 2671

1. Calulate the energy change in the solution in KJ using Q=mcdeltaT where the mass of solutuon =the mass of water + sample being dissolved
2. Calculate the amount of the sample in moles that dissolved
3. Calculate the enthalpy change of solution by dividing Q by the number of moles

Front 2672

Why in an experimental determination of the enthalpy change of solution is the mass of the solid added to the mass of water?

Back 2672

Because the thermometer is in the solution that is changing temperature and so the mass should be the mass of the solution and not the mass of water

Front 2673

What are the two processes that take place when a solid ionic compound dissolves in water?

Back 2673

1. The ionic lattice breaks up
2. Water molecules are attracted to and surrond the ions

Front 2674

What are the two energy changes that occur during the dissolving process?

Back 2674

1. The ionic lattice is broken up to form seperate gaseous ions
2. The separate gaseous ions interact with polar water molecules to form hydrated aqueous ions. The energy change involved is called the enthalpy change of hydration

Front 2675

Define the enthalpy change of hydration?

Back 2675

The enthalpy change that accompanies the dissolving of gaseous ions in water to form one mole of aqueous ions.

Front 2676

What is the symbol for the enthalpy change of hydration?

Back 2676

Front 2677

Calcuate the enthalpy change of solution where c=4.18?

Back 2677

Front 2678

Give the enthalpy changes of hydration of the dissolving of Na^+ Cl^– (g)?

Back 2678

Front 2679

Draw the diagrams and the routes of the enthalpy change of solution?

Back 2679

Front 2680

Back 2680

Front 2681

Back 2681

Front 2682

Give the three general properties of ionic compounds?

Back 2682

1. High melting and boiling points
2. Soluble in polar solvents
3. Conduct electricity when molten or in aqeuous solution

Front 2683

Even though generall ionic compounds have high melting and boiling points give the actual range?

Back 2683

There is a wide range, some ionic compounds can be melted with the heat of a bunsen burner whilst others can be used to coat the inside of furnaces and some are liquids at room temperature

Front 2684

Ionic compounds that are liquids at room temperature are called?

Back 2684

Ionic liquids

Front 2685

Generally many ionic compounds are soluble in polar solvents... describe the actual range of solubilities?

Back 2685

Masny are soluble but others are insoluble

Front 2686

What two factors effect lattice enthalpy?

Back 2686

1. Ionic size
2. Ionic charge

Front 2687

Describe the data in this table? So describe the effect of ionic size?

Back 2687

Front 2688

When attraction decreases the lattice ethanlpy is...

Back 2688

More positive

Front 2689

When attraction increases the lattice enthalpy is...

Back 2689

More negative
ATTRACTION INCREASES SO ENTHALPY DECREASES

Front 2690

Describe the data in this table? So describe the effect of ionic charge?

Back 2690

Front 2691

Describe the difference in lattice enthalpy between NaCl and RbCl?

Back 2691

Na^+ has a smaller cation size than Rb^+ so ionic radius increases down the group, so attraction between ions decreases, so the lattice enthalpy is more positive and melting point decreases

Front 2692

Describe the difference in lattice enthalpy betwee Na2O and CaO?

Back 2692

Na^+ has a smaller ionic charge than Ca^2+ and so attraction between the ions increases so lattice energy becomes more negative and the melting point increases

Front 2693

Describe the effect of the ionic charge and size on attraction between ions?

Back 2693

Front 2694

Describe the opposing effects of the ionic charge and size on lattice enthalpy?

Back 2694

Front 2695

What does the magnitude of lattice energy give a good indication of?


However what else needs to be considered?

Back 2695

The melting point of an ionic compound


The packing of ions in an ionic lattice

Front 2696

What two things affect hydration ethalpies?

Back 2696

1. Ionic size
2. Ionic chrage

Front 2697

Describe the effect of ionic size on hydration enthalpy?

Back 2697

Front 2698

Describe the effect of ionic charge on hydration enthalpy?

Back 2698

Front 2699

When attraction decreases the hydration enthalpy is...

Back 2699

More positive

Front 2700

When attraction increases the hydration enthalpy is...

Back 2700

More negative

Front 2701

What is required for an ionic compound to dissolve?


What does this required?


What happens next?


What does this release?

Back 2701

Attraction between the ions in the ionic lattice must be overcome


Energy equal to the lattice enthalpy


Water molecules are attracted to the positive and negative ions


Hydration enthalpy

Front 2702

When will a compound dissolve in terms of enthalpy changes?

Back 2702

1. When the enthalpy change of solution is exothermic (the sum of the hydration enthalpies is larger than the magntitude of the lattice enthalpy) it should dissolve

2. Enthalpy changes of solution can be exothermic or endothermic and so endothermc enthalpy changes can be soluble

3. Solubility also depends on entropy

Front 2703

Are compounds with endothermic enthalpy changes of solution dissolve?


What does this mean?

Back 2703

Yes, some of them will.


The reasons for solubility also depends on temperature and entropy

Front 2704

What is the symbol for entropy?

Back 2704

S

Front 2705

What three things can entropy be used to explain that occur naturally?

Back 2705

1. Gas spreading through a room
2. Heat from a fire spreading through a room
3. Ice melting in a hot room

Front 2706

Describe the general tendancies of energy in terms of movement?

Back 2706

Energy becomes more spread out. There is a natural tendency for enery to spread out rather than to remain concentrated in one place

Front 2707

Define entropy?

Back 2707

The dispersal of energy and disorder within the chemicals making up a chemical system

Front 2708

The greater the entropy...

How does this translate into units?

Back 2708

...the greater the dispersal of energy and the greater the disorder
So the greater that energy is spread out per Kelvin per Mole

Front 2709

What are the units of entropy

Back 2709

J K^–1 mol^–1

Front 2710

Describe solids, liquids and gases and their entropies?

Back 2710

1. Solids have the smallest entropies
2. Liquids have the greater entropies
3. Gases have the greatest entropies

Front 2711

Describe the entropy at 0K?

Back 2711

There would be no energy and all substances would have an entropy value of zero

Front 2712

Describe the entropy above 0K?

Back 2712

Energy becomes dispersed amongst the particles and all substances have positive entropy

Front 2713

Which systems have a higher entropy value, more or less random?

Back 2713

Systems that are more chaotic have a higher entropy value

Front 2714

Describe what happens to entropy when a system changes to become more random?

Back 2714

Energy can be spread out more, so there will be an entropy change (delta S) which will be positive

Front 2715

Describe what happens to entropy when a system changes to become less random?

Back 2715

Energy becomes more concentrated so the entropy change (delta S) will be negative

Front 2716

How does entropy change with states?

Back 2716

1. Entropy increases during changes in states that give a more random arrangement of particles
2. Solid ––> liquid ––> Gas

Front 2717

Why when a substances changes from a solid to gas does its entropy increase?

Back 2717

Because the melting and boiling increase the randomness of particles so energy is spread out more

Front 2718

Describe how entropy changes here?

Back 2718

1. Production of a gas increases the disorder of particles

2. Energy is spread out more and delta S is positive

Front 2719

Describe how entropy changes here?

Back 2719

1. There is a decrease in the randomness of particles as there are four moles of gas on the left and 2 moles on the right

2. The energy is spread out less and delta S is negative

Front 2720

What does every substance have (Entropy)?

What is this?

Back 2720

A standard entropy

The entropy content of one mole of the substance under a standard state

Front 2721

Define the standard entropy?

Back 2721

The entropy of one mole of a substance under standard conditions 100 kPa and 298 K

Front 2722

Give the symbol for standard entropy?

Back 2722

Front 2723

What are the units of the standrd entropy?

Back 2723

J K^–1 mol^–1

Front 2724

Are standard entropies positive or negative enthalpy changes?

Back 2724

They are always positive

Front 2725

Give the formula to calcuate the entropy change of reaction?

Back 2725

Front 2726

Give the symbol for the entropy change of reaction?

Back 2726

Front 2727

Back 2727

Front 2728

When can a reaction occur in terms of energy?

Back 2728

Wgen the products have a lower overall energy than the reacatants

Front 2729

Define the term feasibility.

Back 2729

It is used to describe whether a reaction is able to happen and is energetically feasible

Front 2730

What other word can be used instead of energetically feasible?

Back 2730

Spontaneous

Front 2731

What is the overall change in energy in a chemical reaction called?

Back 2731

The free energy change

Front 2732

What is the symbol for the free energy change?

Back 2732

Front 2733

Define the free energy change?

Back 2733

The balance between enthalpy, entropy and temperature for a process given by delta G = delta H – T delta. The provess is feasible when delta G < 0

Front 2734

Define the first ionisation energy?

Back 2734

The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions

Front 2735

What two types of energy is the free energy change made up of?

Back 2735

1. The enthalpy change (delta H) this is the heat transfer between the chemical system and the surrondings
2. The entropy change at the temperature of the reaction (T delta S) this is the dispersal of energy within the chemical system itself

Front 2736

Give Gibbs equation?

Back 2736

Front 2737

What equation gives the relationship between delta H and T delta S?

Back 2737

Gibbs equation

Front 2738

What does the feasaility of a reaction depend on?

Back 2738

The balance between delta H and T delta S in the gibbs equation. For a reaction to be feasible there must be a decrease in free energy so delta G < 0

Front 2739

Which energy dominates the gibbs equation?

Back 2739

The delta H values

Front 2740

What are the units of delta H?

Back 2740

kJ mol^–1

Front 2741

What are the units of delta S?

Back 2741

J K^–1 mol^–1

Front 2742

Describe changing the units of delta S in the gibbs equation?

Back 2742

It is of the units J K^–1 mol^–1 so it must be divided by 1000 to get kJ K^–1 mol^–1 so the units match with delta H

Front 2743

Calculate the free energy change of this reaction at 25 degrees?

Back 2743

Front 2744

Back 2744

Front 2745

Back 2745

Delta S= + 581 J K^–1 mol^–1

Front 2746

Back 2746

Front 2747

When can an endothermic reaction occur? (Be feasible... entropy)

Back 2747

When delta H is positive, delta S can be positive also, as long as it is a large value of T delta G will still be negative so the reaction is still feasible

Front 2748

Many reactions have a negative delta G but still do not seem to take place.. why?

Back 2748

1. Very large activation energy
2. Slow rate of reaction
3. Although the sign of delta G indicates the thermodynamic feasibility it takes no account of the kinetics or rate of reaction
4. Rate increases with the addition of a catalyst

Front 2749

Describe reduction in terms of:
1. Electrons
2. Oxidation number

Back 2749

1. Gain of electrons
2. Decrease in oxidation number

Front 2750

Describe oxidation in terms of:
1. Electrons
2. Oxidation number

Back 2750

1. Loss of electrons
2. Increase in oxidation number

Front 2751

Describe the oxidising agent?

Back 2751

Takes electrons from the species being oxidised and so is the species that is reduced

Front 2752

Describe the reducing agent?

Back 2752

It adds electrons to the species being reduced. The reducing agent contains the species that is oxidised

Front 2753

In this equation what is the oxidising and what is the reducing agent?

Back 2753

Ag^+ is the oxidising agent and Cu is the reducing agent

Front 2754

What are the steps for writing redox equations from half equations?

Back 2754

1. Balance the electrons
2. Add and cancel electrons
3. Cancel any species that are on both sides of the equation

Front 2755

Back 2755

Front 2756

What does construction of redox equation using half equations ensure?

Back 2756

That the number of electrons that are transferred balance

Front 2757

What does the construction of redox equation using oxidation number ensure?

Back 2757

That the changes in oxidation number balance

Front 2758

Back 2758

Front 2759

Back 2759

Front 2760

What is a voltaic cell?

Back 2760

It is an electrochemical cell that converts chemical energy into electrical energy

Front 2761

Name the electrochemcial cell that converts chemical energy into electrical energy?

Back 2761

Voltaic cell

Front 2762

Where does the conversion of chemical into electrical energy take place irl?

Back 2762

In many cells and batteries that power devices such as mobile phones

Front 2763

What do cells and batteries convert to power devices such as mobile phones?

Back 2763

Conversion of chemical energy into electrical energy

Front 2764

What does electrical energy result from?

Back 2764

The movement of electrons

Front 2765

What do you need (in terms of the chemistry) for a voltic cell/

Back 2765

As voltaic cells convert chemical energy into electrical energy and electrical energy results from the movement of electrons you need chemical reactions that transfer electrons from one species to another. This is a redox reaction.

Front 2766

How do you make a voltaic cell?

Back 2766

By connecting together two different half cells which allow electrons to flow

Front 2767

Why must the chemicals in two half cells be kept seperate?

Back 2767

It allowed to mix the electrons would flow in an uncontrolled way and heat energy would be released rather than electrical energy

Front 2768

What does a half cell contain?

Back 2768

The chemical species present in a redox half equation

Front 2769

What are the two typesof half cell?

Back 2769

1. Metal/metal ion half cells
2. Ion/ion half cells

Front 2770

Describe a metal/metal ion half cell? ALL

Back 2770

1. Consists of a metal rod dipped into a solution of its aqueous metal ion
2. At the phase boundary where the metal is in contact with its ions an equilibrium is set up
3. In an isolated half cell there is not net transfer of electrons either into or out of the metak
4. When two half cells are connected the direction of electron flow depends on the relative tendency of each electrode to release electrons

Front 2771

Give the equilibrium set up at the phase boundary in a metal metal ion half cell where the solution is Zn^2+?

Back 2771

Zn^2+ (aq) + 2e^– –––><––– Zn(s)

Front 2772

How do you represent a metal/metal ion half cell phase boundary?


Do it for...
1. Zinc 2+ ions
2. Copper 2+ ions

Back 2772

Using a vertical linke for the phase boundary between the aqeuous solution and the metal


1. Zn^2+ (aq)|Zn(s)
2. Cu^2+ (aq)|Cu(s)

Front 2773

By convention, how is the equilibrium in a half cell written?

Back 2773

So that the forward reactions shows recution and the reverse shows oxidation

Front 2774

Draw a zinc metal/metal ion half cell?

Back 2774

Front 2775

Draw a copper metal/metal ion half cell?

Back 2775

Front 2776

Describe a ion/ion half cell? ALL

Back 2776

1. Contains ions of the same element in different oxidation states
2. There is not metal to transport electrons in or out of the half cell so an inert metal electrode made of platinum is used

Front 2777

Give an equation example of an ion/ion half cell containing iron ions?

Back 2777

Fe^3+(aq) + e^– ––><––– Fe^2+(aq)

Front 2778

Draw an ion ion half cell based upon iron?

Back 2778

Front 2779

In two metal/metal ion half cells connected, which electrode has a greater tendency to gain or lose electrons?

Back 2779

1. More reactive metal releases electrons more readily and is oxidised, this is the negatuve electrode as it forms a positive charge so attracts negative electrons
2. The electrode with the less reactive metal gains electrons and is reduced, this is the positive electrode

Front 2780

What is used to measure the tendancy to be reduced and gain electrons?

Back 2780

The standard electrode potential

Front 2781

What is the standard electrode potential?

Back 2781

It is the tendency to be reduced and gain electrons. It is the electromotive force of a half cell connected to a standard hydrogen half cell under standard conditions of 298K, solution concentrations of 1 mol dm^–3 and a pressure of 100kPa.

Front 2782

What is the symbol for the standard electrode potential?

Back 2782

Front 2783

What is the standard for the standard electrode poential?

Back 2783

It is a half cell containing hydrogen gas and a solution containing H^+ (aq) ions with an inert platinum electrode to allow electrons into and out of the half cell

Front 2784

What are the standard conditions for the standard electrode potential?

Back 2784

1. Solutions have a concentration of 1 mol dm^–3
2. Temperature is 298K
3. Pressure is 100kPa

Front 2785

Draw a half cell containing hydrogen gas?

Back 2785

Front 2786

What does e.m.f stand for?


What is it?

Back 2786

Electromotive force


The electrical intensity (potential difference) developed by a source of electrical energy such as a battery or generator

Front 2787

What is the standard electrode potential of a standard hydrogen electrode?

Back 2787

0V

Front 2788

What does the sign of a standard electrode potnential show?

Back 2788

The sign of the half cell connected to the standard hydrogen electrode and shows the relative tendency to gain electrons compared with the hydrogen half cell

Front 2789

Describe the set up of the half cells to measure a standard electrode potential? Brief version

Back 2789

1. The half cell is connected to a standard hydrogen electrode2. The two electrodes are connected by a wire to allow a controlled flow of electrons
3. The two solutions are connected with a salt bridge which allows ions to flow. It is typically a concentrated solution of an electrolyte that does not react with either solution

Front 2790

Give an example of a salt bridge?

Back 2790

A strip of filter paper soaked in aqueous potassium nitrate

Front 2791

Draw the experimental set up for measuring the standard electrode potential of a copper half cell?

Back 2791

Front 2792

In an equilibrium when doing standard electrode potentials, how are they conventially written?

Back 2792

The forward reactions is reduction so the reverse is oxidation

Front 2793

What does a more negative standard electrode potential mean?

Back 2793

1. Has a greater tendency to lose electrons and undergo oxidation
2. The less the tendency to gain electrons and undergo reduction

Front 2794

What does a more positive standard electrode potential mean?

Back 2794

1. Has a greater tendancy to gain electrons and undergo reduction
2. The less the tendency to lose electrons and undergo oxidation

Front 2795

What standard electrode potential value do metals tend to have?

Back 2795

They tend to have negative values and lose electrons

Front 2796

What standard electrode poential values do non metals tend to have?

Back 2796

Positive values and gain electrons

Front 2797

What does it mean, the more negative the standard electrode potential for a metal?

Back 2797

The greater the reactivity of a metal in losing electrons

Front 2798

What does it mean, the more positive the standard electrode potential for a non–metal?

Back 2798

The greater the reactivity of a non metal in gaining electrons

Front 2799

The electromotive force measured from half cells is called what?

Back 2799

A cell potential

Front 2800

What is a cell potential?

Back 2800

The cell potential is the way in which we can measure how much voltage exists between the two half cells of a battery.

Front 2801

What is the symbol for cell potential?

Back 2801

Front 2802

What is the symbol for the standard cell potential?

Back 2802

Front 2803

What is the standard condition for ion/ion half cells?

Back 2803

Both metal ions present in the solution must have the same concentration

Front 2804

Describe how to set up cells to measure standard cell potentials?

Back 2804

1. Prepare two standard half cells
2. Connect the metal electrodes of the half cells to a voltameter using wires
3. Prepare a salt bridge by soaking a strip of filter paper in a saturated aqueous solution of potassium nitrate
4. Connect the two solutions of half cells with a salt bridge
5. Record the standard cell potential from the voltmeter

Front 2805

Describe these results?

Back 2805

1. Copper half cell has the more positive standard electrode potential and so a greater tendancy to undergo reduction and so gain electrons

2. The zinc half cell has a more negative standard electrode potential and so a greater tendency to undergo oxidation and to lose electrons

3. Electrons flow along the wire from the more negative zinc half cell to the less negative copper half cell

4. The zinc electrode is negative and the copper electrode is positive

Front 2806

Write the overall cell equation for copper and zinc connected half cells, with 1.10V being the standard electrode potential and the copper being positive?

Back 2806

Copper gains electrons so: Cu 2^+ + 2e^– ––> Cu (s)Zinc loses electrons so: Zn (s) ––> Zn^2+ (aq) +2e^–

Front 2807

From what can standard cell potentials be calculated?

Back 2807

From standard electrode potentials

Front 2808

Give the equation to find the standard cell potential from standard electrode potentials?

Back 2808

Front 2809

What can you use standard electrode potentials to make predictions about reactions?

Back 2809

About their feasibility

Front 2810

What can you tell about the transfer of electrons from this data?

Back 2810

1. The most negative system has the greatest tendency to be oxidised and lose electrons

2. The most positive system has the greatest tendency to be reduced and gain electrons

Front 2811

Describe why the oxidising agents are on the left and reducing agents are on the right?

Back 2811

Oxidising agents take electrons away from a species being oxidised so are reduced

Reducing agents add electrons to the species being reduced so reducing agents are oxidised

Front 2812

When does a reaction take place between an oxidising agent and a reducing agent?

Back 2812

When the redox system of the oxidising agent has a more positive standard electrode potential value that the redox system of the reducing agent

Front 2813

In this table where is the strongest reducing agent?

Back 2813

The top right

Front 2814

In this table where is the strongest oxidising agent?

Back 2814

The bottom on the left

Front 2815

Draw the three equations that are formed when system C reacts with A, B and C and explain why?

Back 2815

System C has a more positive standard electrode potential value and so has a greater tendency to be reduced than A and B so causes them to be oxidised as it acts as an oxidising agent

Front 2816

Draw the three equations that are formed when system B reacts with A, B and C and explain why?

Back 2816

System B has a more positive standard electrode potential and a greater tendency to be reduced than redox system A.

Front 2817

Draw the three equations that are formed when system A reacts with A, B and C and explain why?

Back 2817

Im not gonna draw these because the oxidizing agent on the left of A will not react as there are no redox systems with a less positive standard electrode potential value

Front 2818

Give the equation for the reaction of A with C?

Back 2818

Front 2819

Give the equation for the reaction of B with C?

Back 2819

Front 2820

Give the equation for the reaction of A with B?

Back 2820

Front 2821

What are the principles about the reactions of redox systems?

Back 2821

1. Redox system with the more positive value will react from left to right and gain electrons
2. The redox system with the less positive value will react from right to left and lose electrons

Front 2822

What is the limitation of predictions for feasibility based on standard electrode potential values and reaction rate?

Back 2822

Reactions have a large activation energy resulting in a slow way. Electrode potentials therefore indicate the thermodynamic feasibilty of a reactions but give no indication of the rate of reaction

Front 2823

What are the four limitations of predictions using standard electrode potential values?

Back 2823

1. Reaction rate
2. Concentration
3. Might not be standard conditions
4. Applies to aqueous equilibria

Front 2824

Describe how concentration is a limitation in prediciting standard electrode potential values?

Back 2824

If the concentration of a solutuon is not 1 mold dm^–3 then the value of the electrode potential will be different from standard value. Any change to the electrode potential will affect the value of the overall cell potential

Front 2825

Describe how concentration may be a limitation of using standard electrode values if it is greater than one mol dm^–3?

Back 2825

The equilibrium will shift to the right to remove electrons from the system and make the electrode potential less negative as it is being more reduced (gaining electrons) as it is forming more solid

Front 2826

Describe how concentration may be a limitation of using standard electrode values if it is less than one mol dm^–3?

Back 2826

The equilibrium position will shift to the left, increasing electrons in the system and making the electrode potential more negative as it is being more oxidised (losing electrons) as it is forming more ions

Front 2827

Describe limitations of predicting standard electrode potential values and standard conditions?

Back 2827

The actual conditions used may be different from the standard conditions used to record standard electrode potential values

Front 2828

Describe limitations of predicting standard electrode potential values and aqueous equilibria?

Back 2828

Many reaction thats take place are not aqueous

Front 2829

What are the two redox titrations you need to know about?

Back 2829

1. Potassium manganate(VII) (KMnO4) under acidic conditions
2. Sodium thiosulfate (Na2S2O3) for determination of iodine

Front 2830

What happens to manganate ions during titrations?


Therefore what must the other chemical used in the titration be?

Back 2830

They are reduced to Mn^2+


A reducing agent that is oxidised

Front 2831

Give the method of a manganate titration?

Back 2831

1. Standard solution of potassium manganate is added to the burette
2. Using a pipette and measured volume of the solution being analysed is added to the conical flask
3. An excess of sulfuric acid is added to provide the H^+ ions required for the reduction of MnO4^–
4. The reaction is self indicating. During the titration the manganate solution reacts and is decolourised as it is being added. The end point of the titration is judged by the first permanent pink colour indicating an excess of MnO4^–
5. Repeat the titration until you obtain concordant titres

Front 2832

Within what values are concordant titres?

Back 2832

Ones that agrees within 0.10 cm ^3

Front 2833

Describe reading the meniscus in the manganate (VII) redox titration?

Back 2833

KMnO4 is a deep purpke colour and it is very difficult to see the bottom of the meniscus through the colour. This means burette readings are read from the top rather that from the bottom of the meniscus. The titre is the same as reading the bottom of the meniscus provided the top is used for both initial and final readings

Front 2834

Give examples of two reducing agents manganate titrations can be used for?

Back 2834

Iron ions (Fe^2+)
Ethanedioic acid

Front 2835

Page 378 (more info on the reverse)

Back 2835

Front 2836

What substances can Manganate titrations be used to analyse?

Back 2836

Any reducing agents that reduce MnO4^– to Mn^2+

Front 2837

What can KMnO4 be replaced with in manganate redox titrations?

Back 2837

Other oxidisng agents such as acidified dirchromate H^+/Cr2O7^2–

Front 2838

What is oxidised and what is reduced in iodine–thiosulfate titrations?

Back 2838

S2O3^2– ions are oxidised and I2 is reduced

Front 2839

Give the equations for oxidation, reduction and overall for the iodine/thiosulfate redox titration?

Back 2839

Front 2840

What four things can iodine/thiosulfate redox titrations be used to determine?

Back 2840

1. Concentration of aqueous iodine
2. ClO^– content in household bleach
3. CU^2+ content in copper(II) compounds
4. CU content in copper alloys


Essentially, analysis of oxidising agents

Front 2841

What is the procedure for the analysis of oxidising agents using iodine/thiosulfate redox titrations?

Back 2841

1. Add a standard solution of Na2S2O3 to the burette
2. Prepare a solution of the oxidising agent to be analysed. Using a pipette add this solution to a conical flask. Then add an excess of potassium iodide, this reacts with the oxidising agent to produce iodine which turns the solution a yellow brown colour
3. Titrate this solution with the Na2S2O3. During the titration the iodine is reduced back to I^– ions and the brown colour fades gradually to a straw yellow (making it difficult to determine an end point)
4. This problem is solved by using a starch indicator. A deep blue black colour forms when it is added and as more sodium thiosulfate is added the blue black colour fades
5. At the end point all the iodine will have just reacted and the blue black colour disappears

Front 2842

How are ions produced from copper salts for iodine/thiosulate redox titrations?

Back 2842

1. By dissolving the compound in water
2. Insoluble compounds can be reacted with acids to form Cu^2+ ions

Front 2843

How are ions produced from copper alloys for iodine/thiosulfate redox titrations? Give an equation

Back 2843

1. Alloy is reacted and dissolved in concentrated nitric acid
2. Neutralisation


Cu(s) ––> Cu^2+

Front 2844

Describe the titration of CU^2+ ions with thiosulfate and iodine?

Back 2844

Front 2845

Page 384

Back 2845

Front 2846

What are the three main types of cell?

Back 2846

1. Primary
2. Secondary
3. Fuel cells

Front 2847

Describe domestically primary cells?

Back 2847

They are nonrechargeable and are designed to only be used once. Used for low current, long storage devices such as wall clocks and smoke detectors

Front 2848

Describe chemically primary cells?

Back 2848

1. Electrical energy is produced by oxidation and reduction at electrodes
2. Reactions cannot be reversed so eventually the chemicals will be used up, the voltage will fall and the battery will go flat
3. Most are alkaline based upon zinc and manganese dioxide Zn|MnO2 with a potassium hydroxide electrolyte

Front 2849

Give the equation for oxidation, reduction and the cell reaction for this primary cell based on Zn/MnO2

Back 2849

Front 2850

Describe secondary cells domestically? (uses but not chemicals)

Back 2850

1. Rechargeable
2. Car batteries
3. Radios and torches
4. Laptops, tablets, cameras and phones

Front 2851

Why is a pimary cell non rechargeable?

Back 2851

Electrical energy is produced by oxidation and reduction at the electrodes. However the reactions cannot be reversed so all the chemicals will be used up

Front 2852

Why is a secondary cell rechargeable?

Back 2852

Cell reaction producing electrical energy can be reversed during recharging. The chemicals in the cell are regernated and the cell can be used again

Front 2853

Give uses of secondary cells?

Back 2853

1. Lead–acid batteries for car batteries
2. Nickel–cadmium NiCd and nickel metal hydride NiMH in radios and torches
3. Lithium ion and lithium ion polymer cells in laptops tablets cameras etc

Front 2854

Lithium is light what does this mean?

Back 2854

Lithium ion batteries have a high energy density

Front 2855

Why do lithium ion batteries have a high energy density?

Back 2855

Because lithium is light

Front 2856

Describe the two shapes lithium ion cells can be?

Back 2856

1. Regular shape like in camera cells
2. Various shapes and sizes

Front 2857

Why can lithium ion cells form various shapes and sizes?

Back 2857

1. Can be made as polymer pouch batteries
2. Have an internal salt bridge made of a microporous polymer covered in electrolytic gel
3. Because this solid polymer is flexible flexible batteries can be formed

Front 2858

What happens when a lithium ion cell charges and discharges?

Back 2858

Charges: Electrons move from the positive electrode to the negative electrode and lithium ions travel from the cathode to the anode


Discharges: Flow from the negative electrode to the positive electrode and lithium ions travel from the anode to the cathode

Front 2859

Generally, what happens when a lithium ion cell charges and discharges?

Back 2859

Electrons move through the connecting wires to power the appliance whilst lithium ions move between the electrode in the cell

Front 2860

In a lithium cell what are the electrodes made out of?

Back 2860

Negative electrode is made out of graphite coated with a lithium metal and the positive electrode is made out of a metal oxide such as CoO2 (cobalt oxide)

Front 2861

Give the simplified reactions at each electrode in a lithium ion cell?

Back 2861

Front 2862

What happens to lithium ions at the positive electrode during discharge?

Back 2862

It reacts to form a lithium ion compound such as LiCoO2

Front 2863

What is the voltage of a lithium ion battery?

Back 2863

4.2V but this drops when in use to around 3.7–3.8V

Front 2864

What are the limitations of lithium ion cells?

Back 2864

1. Unstable at high temperatures and have ignited laptops and mobile phones
2. Care must be taken in their recycling as lithium is very reactive

Front 2865

What does a fuel cell use the energy from?

Back 2865

The reaction of a fuel with oxygen to create a voltage

Front 2866

Describe the three basic principle of a general fuel cell?

Back 2866

1. Fuel and oxygen flow into the cell and the products flow out. The electrolyte remains in the cell
2. Fuel cells can operate continuously provided that the fuel and oxygen and supplied into the cell
3. They do not have to be recharged

Front 2867

What is the most common fuel cell?


Why?


What is being developed based off this?

Back 2867

Hydrogen


Produce no carbon dioxide during combustion


Those using hydrogen rich fuels such as methanol

Front 2868

What are the products of the combustion of hydrogen?

Back 2868

Water is the only product

Front 2869

What two electrolytes can a hydrogen fuel cell have?

Back 2869

1. Alkali
2. Acid

Front 2870

Draw an acid hydrogen fuel cell?

Back 2870

Front 2871

Draw an alkali hydrogen fuel cell?

Back 2871

Front 2872

In the ALKALI hydrogen fuel cell give the equation for the reaction that happens at the anode?

Back 2872

Front 2873

In the ALKALI hydrogen fuel cell give the equation for the reaction that happens at the cathode?

Back 2873

Front 2874

In the ACID hydrogen fuel cell give the equation for the reaction that happens at the anode?

Back 2874

Front 2875

In the ACID hydrogen fuel cell give the equation for the reaction that happens at the cathode?

Back 2875

Front 2876

Give the overall equation for the reaction in an ALKALI hydrogen fuel cell?

Back 2876

Front 2877

Give the overall equation for the reaction in an ACID hydrogen fuel cell?

Back 2877

Front 2878

Describe the properties of all d–block elements?

Back 2878

1. Metallic
2. High melting and boiling points
3. Shiny in appearance
4. Conduct both electricity and heat

Front 2879

What is iron used for?

Back 2879

1. Construction
2. Production of tools

Front 2880

What is copper used for?

Back 2880

1. Electrical cables
2. Water pipes

Front 2881

What is titanium used for?

Back 2881

1. Aerospace industry
2. Medical applications such as joint replacement and cosmetic dentistry

Front 2882

What are the two transititon elements that deviate from the standard pattern of electron filling in orbitals?

Back 2882

Chromium and copper

Front 2883

Why do chromium and copper deviate from the standard pattern of electron filling?

Back 2883

1. Stability
2. Half filled d^5 sub shell and a fully filled d^10 sub shell give additional stability to atoms of chromium and copper

Front 2884

DEscribe where electrons are lost from in transition metals when they form a positive ion?

Back 2884

They lose their 4s electron before losing any of the 3d electrons

Front 2885

Give the stages of emptying/filling of orbitals of transition elements?

Back 2885

1. When forming an atom the 4s oribtial fills before the 3d orbital
2. When forming an ion the 4s orbital empties before the 3d orbital

Front 2886

Give the electron configuration (1s2s etc) for an Fe atom, an Fe^2+ ion and an Fe^3+ ion?

Back 2886

Front 2887

Define a transition element?

Back 2887

A d block element which forms an ion with an incomplete d sub shell

Front 2888

Which two elements deviate from the definition: 'Transition elements are d block element which forms an ion with an incomplete d sub shell'


Therefore what are they not classed as?

Back 2888

Scandium and zinc


They are not classed as transition elements

Front 2889

Describe how scandium deviates from the definition: 'Transition elements are d block element which forms an ion with an incomplete d sub shell'

Back 2889

1. Scandium only forms the ion Sc^3+

2. It has the electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 3d^1 4s^2

3. Sc^3+ has an electron configuration of 1s^22s^22p^63s^23p^6

4. Therefore it has no electrons in a d sub shell

Front 2890

Describe how zinc deviates from the definition: 'Transition elements are d block element which forms an ion with an incomplete d subshell'

Back 2890

1. Zinc only forms the Zn^2+ ion

2. Electron configuration of zinc is 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2

3. Zn^3+ has an electron configuration of 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10

4. Therefore has a full d subshell

Front 2891

What are the three properties of the transition elements that makes them different from other metals?

Back 2891

1. Form compounds in which the transition element has different oxidation states
2. Form coloured compounds
3. The elements and their compounds can act as catalysts

Front 2892

Describe the pattern of number of oxidation states across the transition elements?

Back 2892

The number of oxidation states increases across the transition elements to manganese then decreases

Front 2893

What oxidation state do all transition elements have?

Back 2893

+2

Front 2894

The higher the oxidation state of a transition element...

Back 2894

...the stonger it acts as an oxidising agent

Front 2895

What colour is potassium dichromate?

Back 2895

It is bright orange

Front 2896

What colour is cobalt(II) chloride?

Back 2896

Pink–purple

Front 2897

What colour is nickel (II) sulfate?

Back 2897

Green

Front 2898

What colour is hydrates copper (II) sulfate?

Back 2898

Blue

Front 2899

What happens when solid transition elements are dissolved in water?

Back 2899

They produce coloured solutions

Front 2900

What is the colour of a solution of a transition metal linked to?

Back 2900

It is linked to the partially filled d–orbital of the transition metal ion so the colour of a solution varies with different oxidation states

Front 2901

What is the colour of Iron (II) in solution?

Back 2901

Pale green

Front 2902

Whar is the colour of Iron (III) in solution?

Back 2902

Yellow

Front 2903

What is the colour of Cr(III) in solution?

Back 2903

Green

Front 2904

What is the colour of Cr(VI) in solution?

Back 2904

Yellow or orange

Front 2905

Give four examples of processes that transition metals are used as catalysts in?

Back 2905

1. Haber process
2. The contact process
3. Hydrogenation of vegteable fats
4. Catalytic decomposition of hydrogen peroxide

Front 2906

What is the haber process?


What is the equation?


What is the catalyst?

Back 2906

Manufacture of ammonia from nitrogen and hydrogen


N2 +3H2––><–– 2NH3


Finely divided Iron catalyst

Front 2907

What is the contact process?


What is the equation?


What is the catalyst?

Back 2907

Production of sulfur trioxide from oxdiation of sulfur dioxide


2SO2 + O2 ––><–– 2SO3


V2O5

Front 2908

What is the catalyst for the hydrogenation of vegetable fats in the manufacture of margarine?

Back 2908

Nickel

Front 2909

Give the equation for the catalytic decomposition of hydrogen perioxide?


What is the catalyst?

Back 2909

2H2O2 ––> H2O + O2


MnO2 (manganese oxide)

Front 2910

Give an example of where a homogenous catalyst is a transition element?

Back 2910

The reaction between iodide ions and peroxodisulfate ions S2O8^– is catalysed by Fe^2+ ions

Front 2911

What is the overall reaction between iodide ions and peroxodisulfate ions? (symbol equation)

Back 2911

S2O8^2– + 2I^– ––> 2SO4^2– + I2

Front 2912

How can you show that the reaction between iodide ions and peroxodisulfate ions S2O8^– is catalysed by Fe^2+ ions?

Back 2912

1. When the reaction is carried out with a trace of starch a blue black colour forms showing the formation of iodine
2. If the experiment is repeated with Fe^2+ the blue black solution forms more quickly showing the catalytic action of the metal ion

Front 2913

Show how Fe^2+ catalyses the reaction between iodide ions and peroxodisulfate ions?

Back 2913

Front 2914

Which reactions does Cu^2+ catalyse?
Give an example?

Back 2914

Zinc metals with acid
Zn + H2SO4 ––> ZnSO4 + H2

Front 2915

What is one of the important properties of the d–block elements?

Back 2915

Their ability to form complex ions

Front 2916

Define a complex ion?

Back 2916

A transition metal ion bonded to ligands by dative covalent bonds

Front 2917

Define a ligand?

Back 2917

A molecule or ion that can donate a pair of electrons to a transition metal ion

Front 2918

What colour is hydrated copper(II) sulfate in water?

Back 2918

Blue

Front 2919

Give the formuola of solid hydrated copper(II) sulfate and the complex ion formed when it dissolves in water?

Back 2919

CuSO4.5H2O


[Cu(H2O)6]^2+

Front 2920

Are complx ions restricted to d–block elements?

Back 2920

No! Other elements such as aluminium can also form them

Front 2921

When is a complex ion formed?

Back 2921

When one or more molecules or negatively charged ions bond to a central metal ion known as a ligand

Front 2922

What is the coordination number?

Back 2922

It is the number that indicates the number of coordinate bonds attacthed to a central metal ion

Front 2923

Whart is the number of coordinate bonds attached to a central metal ion called?

Back 2923

The coordination number

Front 2924

Describe how a complex ion is written?

Back 2924

1. Ion is encolsed inside square brackets
2. The overall charge is shown on the outside of the brackets (this is the sum of the charges on the central metal ion and any ligands)

Front 2925

Describe, give and draw the complex ion formed from CrCl3.6H2O is dissolved in water?

Back 2925

1. [Cr(H2O)6]^3+
2. Cr^3+ is the central metal ion
3. Water acts as a ligand as each donates a lone pair of electrons from the oxygen atom to the central metal ion
4. The coordination number is 6 as there a 6 coordinate bonds to the metal

Front 2926

What is a monodentate ligand?

Back 2926

A ligand that is able to donate one pair of electrons to a central metal ion

Front 2927

What is a ligand that is able to donate one pair of electrons to a central metal ion called?

Back 2927

A monodentate ligand

Front 2928

Give examples of five monodentate ligands and their charges?

Back 2928

Front 2929

What are bidentate ligands?

Back 2929

Ligands that can donate two lone pairs of electrons to a metal ion and so form two coordinate bonds

Front 2930

What are ligands that can donate two lone pairs of electrons to a metal ion and so forming two coordinate bonds called?

Back 2930

Bidentate ligands

Front 2931

What are the two most common bidentate ligands? (words)

Back 2931

1,2–diaminoethane (en)
Ethanedioate ion (oxalate ion)

Front 2932

What are the two most common bidentate ligands? (drawing)

Back 2932

Front 2933

Name this compound?

Back 2933

1,2–diaminoethane

Front 2934

Name this compound?

Back 2934

ethanedioate ion (oxalate ion)

Front 2935

Describe how 1,2–diaminoethane acts as a bidentate ligand?

Back 2935

Each nitrogen atom donates a pair of electrons to the central metal ion, forming a covalent bond

Front 2936

Describe how the ethanedioate ion acts as a bidentate ligand?

Back 2936

Each negatively charged oxygen atom donates a lone pair of electrons to the central metal ion

Front 2937

Draw [Co(NH2CH2CH2NH2)3]^3+?

Back 2937

Front 2938

In this, what is the oxidation number of cobalt?


What is the coordination number?

Back 2938

+3

6 because there are three 1,2–diaminoethane ligands and each ligand forms two coordinate bonds

Front 2939

What does the shape of a complex ion depend upon?


What are the most common?

Back 2939

Its coordination number


6 and 4 so 6–coordinate and four coordinate complexes

Front 2940

What shape does a complex ion with a coordination number of six form?

Back 2940

Octahedral

Front 2941

What shape is this molecule, what are the bond angles?

Back 2941

It is octahedral with bond angles of 90 degrees as it has 6 coordinate bonds

Front 2942

What complex ion is formed when MnSO4 is dissolved in water? What shape does this have?

Back 2942

[Mn(H2O)6]^2+

Octahedral with bonds angles of 90 degrees

Front 2943

What are the two common shapes formed by complex ions with a coordination number of four?


Which is more common?

Back 2943

1. Tetrahedral
2. Square planar


Tetrahedral

Front 2944

What shape is [CoCl4]^2–?


Draw it?

Back 2944

Tetrahedral

Front 2945

What shape is [CuCl4]^2–?


Draw it?

Back 2945

Tetrahedral

Front 2946

What colour is [CuCl4]^2– in solution?

Back 2946

Yellow

Front 2947

Whatcolour is [CoCl4]^2– in solution?

Back 2947

Blue

Front 2948

When do square planar shapes occur in complex ions of transition metals?

Back 2948

When they have 8 d electrons in the highest energy d–sub shell

Front 2949

Give examples of three metals that form square planar complexes? (Complex ions)

Back 2949

1. Platinum (II)
2. Palladium (II)
3. Gold (III)

Front 2950

Draw the 3D shape of [Pt(NH3)4]^2+?

Back 2950

Front 2951

What are the two types of stereoisomerism that complex ions can display?

Back 2951

1. Cis trans
2. Optical

Front 2952

What does steroisomerism depend upon in complex ions?

Back 2952

The number and type of ligands that are attached to the central metal ion and the shape of the complex

Front 2953

Which complex ions show cis–trans isomerism?

Back 2953

Some four–coordinate and six–corrdinate complex ions containing two different monodentate ligands

Front 2954

Which complex ions show both cis trans and optical isomerism?

Back 2954

Six–coordinate complex ions containing monodentate and bidentate ligands

Front 2955

In organic chemistry, cis–trans stereoisomeism requires a C+C bond, how is this different to complex ions? General

Back 2955

No double bond is involved and the shape of the complex holds groups in different oreintations about the central metal ion

Front 2956

In which two SHAPES does cis trans isomerism occur?

Back 2956

1. Square planar
2. Octahedral

Front 2957

What are the simplest example of cis trans isomerism in complex ions?

Back 2957

In four coordinate square planar complexes that have no more than two identical ligands attatched to the central metal ion

Front 2958

DESCRIBE the cis isomer of [Pd(NH3)2Cl2]

Back 2958

In square planar complexes the ligands are arranged in the same plane at the courners of a square with 90 degree bond angles. The two identical groups are adjacent to each other with the coordinate bonds being 90 degrees apart.

Front 2959

DESCRIBE the trans isomer of [Pd(NH3)2Cl2]

Back 2959

In square planar complexes the ligands are arranged in the same plane at the corners of a square with 90 degree bond angles. The two identical groups are opposite each other, the coordinate bonds between identical ligands are 180 degrees apart

Front 2960

DRAW the cis isomer of [Pd(NH3)2Cl2]

Back 2960

Front 2961

DRAW the trans isomer of [Pd(NH3)2Cl2]

Back 2961

Front 2962

Which six coordinate complex ions can show cis–trans isomerism?

Back 2962

1. Ones that contain four of one type of ligands and two of another type
2. Ones that contain bidentate ligands

Front 2963

DESCRIBE the cis isomer of [Co(NH3)4Cl2]^+

Back 2963

The two chloride liands are adjacent to each other with their coordinate bonds separated by 90 degrees. It is violet.

Front 2964

DESCRIBE the trans isomer of [Co(NH3)4Cl2]^+

Back 2964

The two chloride ligands are at opposite courners of the octahedron with their coordinate bonds 180 degreees apart. It is green.

Front 2965

DRAW the cis isomer of [Co(NH3)4Cl2]^+

Back 2965

Front 2966

DRAW the transisomer of [Co(NH3)4Cl2]^+

Back 2966

Front 2967

Draw the cis isomer of [Co(NH2CH2CH2NH2)2Cl2]^+?

Back 2967

Front 2968

Draw the trans isomer of [Co(NH2CH2CH2NH2)2Cl2]^+?

Back 2968

Front 2969

DESCRIBE the cis isomer of [Co(NH2CH2CH2NH2)2Cl2]^+?

Back 2969

The two 1,2–diaminoethane ligands are adjacent to each other

Front 2970

DESCRIBE the trans isomer of [Co(NH2CH2CH2NH2)2Cl2]^+?

Back 2970

The two 1,2–diaminoethane ligands are at opposite courners of the octahedron

Front 2971

When does optical isomerism in complex ions occur?

Back 2971

It occurs only in octahedral complexes containing two or more bidentate ligands

Front 2972

Draw the two opitcal isomers of the cis isomer of [Co(NH2CH2CH2NH2)2Cl2]^+?

Back 2972

Front 2973

Draw the two optical isomers [Ru(NH2CH2CH2NH2)3]^2+?

Back 2973

Front 2974

What happens when a platinum electrode is used to apply an electrical current to a colony of E.coli?


What was initially thought?


What was formed at the electrode?

Back 2974

The E.coli failed to divide but continued to grow


Electric current was preventing cell division


Platinum compound called cis–platin

Front 2975

Draw cis–platin?

Back 2975

Front 2976

What does cis–platin do? DESCRIBE ALL POINTS

Back 2976

1. It attacks tumours and shrinks them in size.
2. Unpleasant side effects like kidney damage.
3. Used in treatment of cancer
4. Clinical trials continuing looking into platinum based drugs
5. Forms platinum complex inside of cell which binds to DNA and prevents the DNA from replicating
6. Activation of the cell repair mechanisms leads to apoptosis

Front 2977

What is a ligand substitution reaction?

Back 2977

A reaction in which one ligand in a complex ion is replaced by another ligand

Front 2978

What happens to the colour of the solution when aqueous ammonia is added to [Cu(H2o)6]^2+?

Back 2978

The pale blue solution changes colour to form a dark blue solution

Front 2979

Give the equation for whenaqueous ammonia is added to [Cu(H2o)6]^2+?

Back 2979

Front 2980

What are the two different reactions taking place in this equation?

Back 2980

1. A pale blue precipitate of Cu(OH)2 is formed in the first stage the reaction

2. The Cu(OH)2 precipitate then dissolves in excess ammonia to form a dark blue solution

Front 2981

What colour is Cu(OH)2?

Back 2981

Pale blue precipitate

Front 2982

How should ammonia be added to the solution in this reaction? Why?

Back 2982

Drop–wise so that all observation are recorded

Front 2983

Draw [Cu(NH3)4(H2O)2]^2+?

Back 2983

Front 2984

Give the equation for the formation of [Cu(NH3)4(H2O)2]^2+ from [CU(H2O)6]^2+?

Back 2984

Front 2985

What is the colour [Cu(H2O)6]^2+

Back 2985

Pale blue

Front 2986

What happens to the colour of [Cu(H2O)6]^2+ when HCl is added?

Back 2986

The pale blue changes colour to form a yellow solution passing through an intermediate green stage

Front 2987

What happens to the colour of [Cu(H2O)6]^2+ when HCl is added and then water is added?

Back 2987

It goes from pale blue to green to yellow back to pale blue

Front 2988

Describe what happens chemically in the reaction between [Cu(H2O)6]^2+ plus HCl?

Back 2988

Six water ligands have been replaced with four chloride ligands

Front 2989

Why is there a green intermediate solution in the reation between [Cu(H2O)6]^2+ and HCl?

Back 2989

It is not a new species but is the result of the yellow solution of [CuCl4]^2– mixing with the blue solution of [Cu(H2O)6]^2+

Front 2990

Give the equation that shows the reaction between [Cu(H2O)6]^2+ and chloride ions?

Back 2990

Front 2991

What three things change in the reactoionbetween [Cu(H2O)6]^2+ and chloride ions?

Back 2991

1. Coordination number (6 to 4)
2. Colour (pale blue to yellow)
3. Change in shape (octrahedral to tetrahedral)

Front 2992

Why does the shape change from octahedral to tetrahedral?

Back 2992

Chloride ligands are larger in size than the water ligands so fewer chloride ligands can fit around the central Cu^2+ ion

Front 2993

Things change in the reaction between [Cu(H2O)6]^2+ and chloride ions such as colour and coordination number, what remains the same?

Back 2993

The oxidation state of the copper remains as a +2

Front 2994

What complex ion is formed when KCr(So4)2.12H2O is dissolved in water?

Back 2994

[Cr(H2O)6]^3+

Front 2995

What is KCr(So4)2.12H2O called?

Back 2995

chromium(III) potassium sulfate/Chrome alum

Front 2996

What colour is [Cr(H2O)6]^3+ in solution?

Back 2996

Pale purple

Front 2997

What is formed when chromium (III) sulfate is dissolved in water, what colour is this?

Back 2997

Green solution of chromium (III) of the complex ion [Cr(H2O)5SO4]^+ is formed

Front 2998

What is the same between [Cr(H2O)5SO4]^+ and [Cr(H2O)6]^3+?

Back 2998

They both contain chromium ions in oxidation state +3

Front 2999

What is different between [Cr(H2O)5SO4]^+ and [Cr(H2O)6]^3+?

Back 2999

One of the water ligands has been replaced by a sulfate ion in [Cr(H2O)5SO4]^+.[Cr(H2O)5SO4]^+ is green whereas [Cr(H2O)6]^3+ is pale purple

Front 3000

What is compound formed from the reaction of [Cr(H2O)6]^3+ with ammonia?

Back 3000

[Cr(NH3)6]^3+ is formed

Front 3001

What colour is [Cr(NH3)6]^3+?

Back 3001

Purple

Front 3002

Describe the stages of colour change when ammonia is added to [Cr(H2O)6]^3+?

Back 3002

1. Initially a grey–green precipitate of Cr(OH)3 is formed
2. The Cr(OH)3 precipitate dissolves in excess ammonia to form the complex ion[Cr(NH3)6]^3+ which is purple

Front 3003

Give the equation for the reaction of [Cr(H2O)6]^3+ with ammonia?

Back 3003

Front 3004

What is the name of the complex formed when carbon monoxide binds to haemoglobin?

Back 3004

Carboxyhaemoglobin

Front 3005

What happens in terms of ligands if carbon monoxide is breathed in?

Back 3005

1. A ligand substitution reaction takes place
2. Oxygen in haemoglobin is replaced by carbon monoxide as carbon monoxide binds to haemoglobin more strongly than oxygen
3. The bond is so strong that the process is irreversible
4. This can lead to death

Front 3006

With which substances do transititon metal ions react with to form precipitates?

Back 3006

1. Sodium hydroxide
2. Aqueous ammonia

Front 3007

Transition metal ions react to form precipitates, however describe what these can go on to form?

Back 3007

Transition metals react with sodium hydroxide and ammonia to form precipitates. However some of these will dissolve in an excess of sodium hydroxide or ammonia to form complex ions in solution

Front 3008

What is the colour of Cu^2+ ions?

Back 3008

Blue

Front 3009

What is the colour of Fe^2+ ions?

Back 3009

Very pale green

Front 3010

What is the colour of Fe^3+ ions?

Back 3010

yellow (pale)

Front 3011

What is the colour of Mn^2+ ions?

Back 3011

Pale pink

Front 3012

What happens when Cu^2+ reacts with sodium hydroxide?


What happens when you add excess sodium hydroxide?

Back 3012

Blue solution reacts to form a blue precipitate of copper (II) hydroxide Cu(OH)2


The precipitate is insoluble in excess sodium hydroxide

Front 3013

Give the ionic equation for the reaction of Cu^2+ with NaOH?

Back 3013

Front 3014

What happens when Fe^2+ reacts with sodium hydroxide? Colour changes plz
What happens when you add excess sodium hydroxide?
Is there any other changes?

Back 3014

A pale green solution reacts to form a green precipitate of iron (II) hydroxide Fe(OH)2
Precipitate is insoluble in excess sodium hydroxide
Turns brown at its surface on standing in air as iron(II) is oxidised to iron (III)

Front 3015

Give the equation for Fe^2+ reacting with sodium hydroxide?

Back 3015

Front 3016

Give the equation for Iron (II) hydroxide in air?

Back 3016

Front 3017

What happens when Fe^3+ reacts with sodium hydroxide?


What happens when you add excess sodium hydroxide?

Back 3017

Pale yellow solution reacts to form an orange–brown precipitate of iron(III) hydroxide Fe(OH)3


The precipitate is insoluble in excess sodium hydroxide

Front 3018

Give the equation for the reaction of Fe^3+ with sodium hydroxide? Balanced and state symbols

Back 3018

Front 3019

What happens when Mn^2+ reacts with sodium hydroxide?

What happens when you add excess sodium hydroxide?


Is there any other changes?

Back 3019

Pale pink solution reacts to form a light brown precipitate of manganese (II) hydroxide Mn(OH)2


It is insoluble in excess sodium hydroxide


It darkens on standing in air

Front 3020

Give the equation for the reaction of Mn^2+ with sodium hydroxide?

Back 3020

Front 3021

What colour are Cr^3+ ions in solutiuon?

Back 3021

Green

Front 3022

What happens when Cr^3+ reacts with sodium hydroxide?

What happens when you add excess sodium hydroxide?

Back 3022

Forms a grey–green precipitate of chromium (III) hydroxide


The precipitate is soluble in excess sodium hydroxide, forming a dark green solution

Front 3023

Give the overall equation for the reaction of Cr^3+ ions with sodium hydroxide and then excess sodium hydroxide?

Back 3023

Front 3024

Give the equation for the reaction of Cr^3+ with sodium hydroxide?


Give the equation for the product of the above reaction with excess sodium hydroxide?

Back 3024

Front 3025

What happens to the colour when Cu(OH)2 is dissolved in excess ammonia?

Back 3025

It forms a deep blue solution

Front 3026

What happens when Cu(OH)2 is dissolved in excess ammonia?

Back 3026

Forms the complex ion [Cu(NH3)4(H2O)2]^2+

Front 3027

What happens to the colour when Cr(OH)3 dissolves in excess ammonia?

Back 3027

Turns from green to purple

Front 3028

What happens when Fe^2+, Fe^3+ and Mn^2+ react with excess ammonia? (Individually, not as one reaction)

Back 3028

They react in the same way they react with sodium hydroxide forming precipitates of Fe(OH)2, Fe(OH)3 and Mn(OH)2. There is no further reaction with aqueous ammonia and so these precipitates do not dissolve

Front 3029

What happens when Fe^2+ reacts with excess ammonia?

Back 3029

Reacts in the same way it reacts with sodium hydroxide forming a precipitate of Fe(OH)2. There is no further reaction with aqueous ammonia and so the precipitate does not dissolve

Front 3030

What happens when Fe^3+ reacts with excess ammonia?

Back 3030

Reacts in the same way it reacts with sodium hydroxide forming a precipitate of Fe(OH)3. There is no further reaction with aqueous ammonia and so the precipitate does not dissolve

Front 3031

What happens when Mn^2+ reacts with excess ammonia?

Back 3031

Reacts in the same way it reacts with sodium hydroxide forming a precipitate of Mn(OH)2. There is no further reaction with aqueous ammonia and so the precipitate does not dissolve

Front 3032

What colour is MnO4^–?

Back 3032

Purple

Front 3033

What colour is Mn^2+?

Back 3033

Pale pink

Front 3034

In a manganate tritration, what is MnO4^– reduced to?

Back 3034

Mn^2+

Front 3035

In a manganate titration what is Fe^2+ oxidised to?

Back 3035

Fe^3+

Front 3036

Give the overall equation for the reaction between manganate ions and Fe ^2+ ions in the manganate iron titration?

Back 3036

Front 3037

What can be used to oxidise Fe^2+ to Fe^3+?

Back 3037

MnO4^–


Manganate (VII) ions

Front 3038

What can be used to reduce Fe^3+ to Fe^2+?

Back 3038

Iodide ions

Front 3039

What happens when Fe^2+ reacts with MnO4^– in terms of redox?

Back 3039

Fe^2+ is oxidised to Fe^3+ and MnO4^– is redcued to Mn^2+

Front 3040

What happens when Fe^3+ reacts with I^– ions in terms of colour?

Back 3040

Orange brown Fe^3+ becomes pale green. However this colour change is obscured by that of iodide ions, I2 is formed which has a brown colour.

Front 3041

What happens when Fe^3+ reacts with I^– ions in terms of redox?

Back 3041

Fe^3+ is reduced to Fe^2+ and I^– are oxidised to I2

Front 3042

Give the equation for the reaction of Fe^3+ ions with I^– ions? Colour changes?

Back 3042

Front 3043

Use this data to explain what happens to Fe^2+ with MnO4^–?

Back 3043

1. Standard electrode potential of iron is less positive than for manganate

2. Therefore MnO4^– acts as a oxidising agent and Fe^2+ is oxidised to Fe^3+ and MnO4^– is reduced to Mn^2+

Front 3044

Use this data to explain what happens to Fe^3+ with I^–?

Back 3044

1. Standard electrode potential of iron is more positive than for iodine

2. Therefore Fe^3+ acts as a oxidizing agent and Fe^2+ is reduced to Fe^3+ and MnO4^– is oxidised to Mn^2+

Front 3045

How can acidified Cr2O7^2– ions be reduced to Cr^3+ ions?

Back 3045

By the additon of zinc

Front 3046

Give the equation for the reaction of Cr2O7^– with zinc?

Back 3046

Front 3047

What colour change occurs when Cr2O7^2– reacts with zinc?


What happens when the above product is reduced with excess zinc?

Back 3047

From orange to green


Green to pale blue

Front 3048

Give the equation for the reaction of Cr^3+ ions and excess zinc?

Back 3048

Front 3049

What is the most powerful reducing/oxidising agent?

Back 3049

Zinc is the most powerful reducing agent so Cr^3+ is the strongest oxidizing agent

Front 3050

What can hot alkaline hydrogen peroxide be used as?

Back 3050

A powerful oxidising agent

Front 3051

What can be used to oxidise chromium (III) in Cr^3+ to chromium (VI) in Cr2O7^–?

Back 3051

How alkaline hydrogen perioxide as it is a powerful ocidising agent

Front 3052

Give the overall equation for the oxidation of Cr^3+ to CrO4^–?

Back 3052

Front 3053

Give the reduction equantion for H2O2 to OH^-?
Give the oxidation equation for Cr^3+ to CrO4^–?
Give the overall equation?

Back 3053

H2O2 +2e^– ––> 2OH^–
Cr^3+ + 8OH^– ––> CrO4^2– + H2O + 3e^–

Front 3054

What happens in terms of redox when aqeous copper (II) ions react with iodide ions?


Give the equation for the reaction?

Back 3054

A redox reaction occurs:
1. I^– is oxidised to brown iodine
2. Cu^2+ is redcued to Cu^+
3. The Cu^+ forms a white precipitate of copper (I) iodide

Front 3055

What colour is copper (I) iodide?

Back 3055

White precipitate

Front 3056

What colour is I2?

Back 3056

Brown

Front 3057

What colour are copper (II) ions?


What colour are iodide ions?


What colour is iodine?


What colour is copper (I) iodide?

Back 3057

Pale blue


Colourless


Brown


White precipitate

Front 3058

What is formed when copper (I) oxide reacts with hot dilute sulfurci acid? Colours not equation

Back 3058

1. Brown precipitate of copper
2. Blue solution of copper (II) sulfate

Front 3059

What are the conditions for the reaction of copper (I) oxide with sulfuric acid?

Back 3059

The sulfuric acid must be hot and dilute

Front 3060

Why is the reaction of solid copper (I) oxide with hot dilute sulfuric acid an example of a disproportionation reaction?

Back 3060

Because Copper (I) has been simultaneously oxidised and reduced. It reduced to a brown precipitate of copper and oxidised so a blue solution of copper sulfate

Front 3061

Give the equation for the reaction between copper (I) oxide and hot dilute sulfuric acid?

Back 3061

Front 3062

What is oxidised and what is reduced in this equation?

Back 3062

Cu^+ in Cu2O is reduced to Cu as it gains 1 electron

Cu^+ in Cu2O is oxidised as it loses one electron to form Cu^2+ in CuSO4

Front 3063

What happens when ammonium ions are heated with hydroxide ions (not equation)

Back 3063

React to produce ammonium gas and water

Front 3064

Give the equation for the reaction of hydroxide ions and ammonium ions?

Back 3064

Front 3065

What is the test for the ammonium ions?

Back 3065

1. Aqeous sodium hydroxide is heated with solution being analysed
2. If ammonia is evolved, damp red pH indicator paper will turn blue

Front 3066

What is the test for the ammonium ions?

Back 3066

1. Aqeous sodium hydroxide is heated with solution being analysed
2. If ammonia is evolved, damp red pH indicator paper will turn blue

Front 3067

Back 3067

Front 3068

Back 3068