Acid rain Flashcards
acid rain
acid rain is rain that is more acidic than normal (<5 pH)
rainwater is naturally slightly acidic, 6-7 pH
sulfur dioxide in fuels
hydrocarbon fuels may contain impurities such as sulfur compounds
fuels are burnt in power stations and vehicles
when the fuels burn, the sulfur is oxidised to form sulfur dioxide
sulfur + oxygen -> sulfur dioxide
S(s) + O2(g) -> SO2
sulfur dioxide and forming acid rain
non-metal oxide
dissolves in rainwater to form an acidic solution
-SO2 + H2O -> H2SO3
forms sulfurous acid
-H2SO3 + O2 -> 2H2SO4
sulfurous acid reacts with oxygen in the atmosphere and becomes sulfuric acid
acid rain is a mixture of diluted sulfurous and sulfuric acid
effects of acid rain on plants/animals
soil becomes more/too acidic
- crops don’t grow because of the pH
- plants can’t absorb nutrients in the soil
- organisms in soil are harmed
rivers and lakes become too acidic
- kills fish and insects (because of pH)
- prevents fish eggs from hatching
trees are damaged
-directly from the rain and also from the soil being acidic
effects of acid rain on buildings
acid breaks the structure of limestone/marble
-causes weathering/erosion of buildings
-calcium carbonate + sulfuric acid -> calcium sulfate + water + carbon dioxide
reacts with metals
-increasing rate of corrosion (weakens them)
-iron + sulfuric acid -> iron (III) sulfate + hydrogen
reducing environmental damage
- removing sulfur from petrol, diesel, fuel oil at refinery before selling
- flue gas defulfurisation to prevent sulfur dioxide leaving power station chimneys
- adding calcium carbonate or calcium hydroxide to fields and lakes to neutralise excess acid from acid rain
- catalytic converters in internal combustion engines remove most NOx gases
formation of nitrogen oxides
internal combustion engines:
- (diesel) car engines
- fuel mixes with air and ignites (mini explosions)
- temperature reaches high enough levels to allow nitrogen and oxygen in the air to react together
- forms oxides of nitrogen
nitrogen oxides, acid rain and other environmental problems
- NOx forms nitric acid when it reacts with moisture in the air
- forms acid rain
- oxides of nitrogen also cause respiratory disease/bronchitis
- reacts with pollutants when in sunlight to create photochemical smog
photochemical smog
mixture of fog, oxides of nitrogen, and sunlight
Oxides of nitrogen, NOx, are atmospheric pollutants. They may contribute to acid rain.
a) Explain why oxides of nitrogen are produced when hydrocarbon fuels are used in vehicle and aircraft engines
b) Balance the equation to represent the production of nitrogen dioxide:
N2(g) + O2(g) -> NO2(g)
a) air goes into the engine so the fuel can burn
N2 and O2 from the air react together at the high temperatures in the engines to produce oxides of nitrogen
b) N2 + 2O2 -> 2NO2
State two environmental problems caused by acid rain
- weathering of buildings/statues
- damage to trees
- harm to living things in river/lakes/soil
Explain why, when hydrocarbon fuels are used:
a) sulfur dioxide is produced
b) oxides of nitrogen are produced
a) hydrocarbon fuels contain impurities of sulfur compounds
sulfur is oxidised to sulfur dioxide when the fuel is used
b) nitrogen and oxygen from the air react together in the high temperatures inside an engine