Chemistry C3 Ocr Gateway B

Front 1

What is an exothermic reaction?

Back 1

One which gives out energy usually in heat

Front 2

How is an exothermic reaction shown?

Back 2

A rise in temperature

Front 3

What is an example of an exothermic reaction?

Back 3

Combustion

Front 4

What is an endothermic reaction?

Back 4

One that takes in energy, usually in heat

Front 5

How is an endothermic reaction shown?

Back 5

A fall in temperature

Front 6

What is an example of an endothermic reaction?

Back 6

Thermal decomposition

Front 7

How do you decide whether a reaction is endo or exo?

Back 7

You can measure the amount of energy produced by taking the temperature of the reactants and mix in a polystyrene cup and measure the temperature of the solution at the end

Front 8

What happens during a chemical reaction?

Back 8

Old bonds are broken and new bonds are formed

Front 9

Is bond breaking an exothermic or an endothermic reaction?

Back 9

Endothermic because energy is supplied

Front 10

Is bond making an exothermic or an endothermic reaction?

Back 10

Exothermic because it releases energy when formed

Front 11

Explain the calorimetric method ued to measure the energy content of fuels

Back 11

1. Reduce draughts so as much heat as possible goes into heating the water eg. use a screen
2. Put fuel in spirit burner and weigh
3. Measure water into a copper calorimeter
4. Take initial temperature of water and light wick
5. When water temperature has raised by 20-30 degrees, note the highest temperature of water
6. Reweigh the burner
7. Repeat if comparing fuels

Front 12

What is the equation for energy given out per gram?

Back 12

Energy per g = energy released / mass of fuel burnt

Front 13

Name 4 ways to keep the calorimetric test fair

Back 13

Same equipment
Same amount of water
Water initial and final temperatures = same
Repeat

Front 14

Give an example of a slow chemical reaction?

Back 14

Rusting

Front 15

Give an example of a fast chemical reaction?

Back 15

Burning

Front 16

The rate of reaction that produces a gas can be observed by measuring how quickly the gas is produced. Name two ways of doing this.

Back 16

- Measure the change in mass = mass falls as gas produced
- Measure cm(cubed) of gas given off = gas syringe

Must do these at regular intervals

Front 17

What two things does the rate of reaction depend on?
Explain why

Back 17

Collision frequency = more collisions = faster

Energy transferred in collision = enough energy to be successful

Front 18

What effect does an increase in temperature have on collisions?

Back 18

They move quicker = more collisions
Increases energy of collisions = more successful collisions

Front 19

What effect does an increase in concentration or pressure have on collisions?

Back 19

More particles in the same space = closer together = more collisions

Front 20

What effect does an increase in surface area have on collisions?

Back 20

More surface area exposed = more area to work on = collisions will increase

Front 21

What effect does a catalyst have on collisions?

Back 21

Provides surface where reactions can take place.
Lowers the activation energy (reduces the energy needed by particles to react)

Front 22

What is the equation for atom economoy?

Back 22

Atom economoy = Total Mr of desired products / Total Mr of all products (x100)

Front 23

Why does a high atom economy benefit the environment?

Back 23

Reactions with low atom economy use up resources very fast
Make lots of waste = has to be disposed of = unsustainable

Front 24

How does atom economy effect profits?

Back 24

The lower the atom economy = aren't profitable because expensive to buy materials and waste products can be expensive to dispose responsibly of

Front 25

What is the equation for percentage yield?

Back 25

Percentage yield = actual yield (g) / predicted yield (g)
(x100)

Front 26

Give four reasons for why yields are always less than 100%?

Back 26

- Evaporation
- Filtration (solid/liquid some left behind)
- Transferring liquids (some remain on inside of old container)
- Not all reactants make a product

Front 27

Give 2 advantages of batch production

Back 27

Flexible = several different products made using the same equipment
Low start up costs

Front 28

Give 2 disadvantages of batch production

Back 28

Labour intensive
Difficult to obtain the same quality in each batch

Front 29

Give 3 advantages of continuous production

Back 29

Never stops = no time is wasted emptying reactors and setting up again
Runs automatically
Quality is always consistent

Front 30

Give a disadvantage of continous production

Back 30

Start up costs are very high

Front 31

Give an example of a product made by batch production

Back 31

Pharmaceutical drugs

Front 32

Give an example of a product made by continous production

Back 32

Ammonia (haber process)

Front 33

What is the pharmaceutical drug making process?

Back 33

- Research and development
- Testing/trialling to ensure it works and is safe
- Manufacture

Front 34

What two things make drugs expensive to make?

Back 34

- Raw materials (extracted from plants)
- Energy

Front 35

How do you extract a substance from a plant?

Back 35

It has to be crushed, boiled and dissolved in a suitable solvent
Then use chromatography to extract the substance you want

Front 36

How can you tell if a substance is pure with chromotography?

Back 36

It won't be seperated by chromotography (one blob)

Front 37

How can you tell if a substance is pure by the boiling/melting points of thesubstance?

Back 37

They have specific melting points
If a substance is impure, the melting point will be too low and the boiling point too high

Front 38

Give four properties of diamond

Back 38

Lustrous
Colourless
Strong covalent bonds = high melting point
Doesn't conduct electricity

Front 39

What makes diamond very hard?

Back 39

Each carbon atom forms four covalent bonds in a very rigid giant covalent structure = very hard

Front 40

Why is diamond useful as a cutting tool?

Back 40

-Really hard because of giant covalent structure
-Has a high melting point

Front 41

Give five properties of graphite

Back 41

Black
Opaque
Shiny
High melting point
Conducts electricity

Front 42

Explain the structure of graphite

Back 42

Each carbon atom only forms three covalent bonds, creating sheets of carbon atoms which are free to slide over each other

Front 43

Why can graphite conduct electricity?

Back 43

Since only 3 out of each carbons 4 outer electrons are used in bonds, there are lots of delocalised electrons which move

Front 44

What three properties do all giant molecular structures share?

Back 44

Strong, high melting points and don't dissolve in water

Front 45

What are fullerenes?

Back 45

Molecules of carbon shaped like closed tubes/hollow balls

Front 46

What is a use of a fullerene?

Back 46

To "cage" other moleculs = eg. new way of delivering a drug to the body for slow release?

Front 47

What can fulluerenes be joined together to make?

Back 47

Nanotubes which are tiny hollow carbon tubes

Front 48

What is a use of a nanotube?

Back 48

Have a large surface area = industrial catalysts