Acids & Bases

Front 1

what is an acid?

Back 1

a substance that dissociates to produce hydrogen ions when dissolved in water

Front 2

what are the properties of an acid?

Back 2

- sour

- ph < 7

- turns blue litmus red

- strong acids are strong electrical conductors due to their high concentration of mobile ions

Front 3

what is a base?

Back 3

a substance that reacts with acids to produce salts and water only

Front 4

what is an alkali?

Back 4

a substance that produces hydroxide ions when dissolved in water

Front 5

what are the properties of a base/alkali?

Back 5

- bitter & soapy

- turns red litmus blue

- pH > 7

- strong alkalis are strong electrical conductors due to the high concentration of mobile ions

Front 6

what are the reactions that can take place?

Back 6

1. acid + metal -> salt + hydrogen

2. acid + carbonate -> salt + carbon dioxide + water

3. acid + alkali -> salt + water

4. alkali + ammonium salt -> salt + ammonia + water

5. acid + sodium sulfite -> sodium salt + sulfur dioxide + water

Front 7

what is the strength of an acid/alkali?

Back 7

- extent of dissociation

- strong acids & alkalis dissociate fully in water to produce hydrogen/hydroxide ions

- weak acids & alkalis dissociate partially in water to produce hydrogen/hydroxide ions

Front 8

what is the concentration of an acid/alkali?

Back 8

the amount of solute dissolved in a fixed volume of solvent

Front 9

what is the pH scale?

Back 9

- pH level shows the concentration of hydrogen ions in a solution

- determines whether it is an acid or a base

- 1 is very acidic and 14 is most alkaline, 7 is neutral

Front 10

what are indicators?

Back 10

change colour to show the pH level in solution

Front 11

what are oxides?

Back 11

compounds that consist of oxygen and another element

Front 12

what are basic oxides?

Back 12

- react with acids to form salt and water

- do not react with bases

- metal solids

- mostly insoluble but group 1, CaO & BaO are soluble

Front 13

what are amphoteric oxides?

Back 13

- reacts with acids and bases to form salt and water

- insoluble in water

- all metal oxides are basic except ZnO, Al2O3, PbO

Front 14

what are acidic oxides?

Back 14

- non-metal oxides

- reacts with bases to form salt and water

- do not react with acids

- most are gases

- soluble in water: NO2, P2O5, CO2, SO2, SO3

- insoluble in water: SiO2

Front 15

what are neutral oxides?

Back 15

- do not react with acids or bases

- insoluble in water

- all non-metal oxides are acidic except NO, CO, H2O

Front 16

what are sources of air pollution?

Back 16

- carbon monoxide

- sulfur dioxide

- oxides of nitrogen

- unburnt hydrocarbons

- methane

- ozone

Front 17

what are ways to reduce air pollution?

Back 17

- prohibition of burning open waste

- unleaded petrol

- reduction of permissible level of sulfur in diesel

- catalytic converter

Front 18

what is acid rain?

Back 18

- pH < 4

- SO2(g) + H2O(l) -> H2SO3(aq)

- 4NO2(g) + 2H2O(l) + O2(g) -> 4HNO3(aq)

- reacts with metals & carbonates in buildings

- leeches nutrients from soil

- reduces pH in water bodies

Front 19

what are ways to reduce acid rain?

Back 19

liming: use of calcium carbonate to temporarily restore water bodies

Front 20

what is flue gas desulfurization?

Back 20

- process of removing sulfur dioxide from waste gases

- CaO(s) + SO2(g) -> CaSO3(s)

- CaCO3(s) + SO2(g) ->CaSO3(g) + CO2(g)

2CaSO3(g) + O2(g) -> CaSO4(s)

Front 21

what are catalytic converters?

Back 21

- devices in vehicles that carry out reactions to make pollutants harmless

- 2C8H18(l) + 25O2(G) ->16O2(g) + 18H2O(l)

- 2NO(g) + 2CO(g) -> N2(g) + 2CO2(g)

- 2CO(g) + O2(g) -> 2CO2(g)