sulphur
dioxide.S(s) + O2(g)
SO2(g)gcsescience.com 79 gcsescience.com
Environmental Issues.
2) Fossil fuels are burnt on a huge scale - Acid Rain.
Coal
(and to a lesser degree Oil and
Natural Gas) contain sulphur.
When they are burnt the sulfur
oxidises
(reacts with oxygen)
to form sulfur dioxide
gas.
sulfur
+ oxygen
sulphur
dioxide.
S(s) +
O2(g)
SO2(g)
Sulfur
dioxide gas is acidic,
poisonous, and smells of bad
eggs.
It is removed from the burnt waste
gases and used in the contact process.
If it gets into the atmosphere it
reacts with water and oxygen in
the air
to form a dilute solution of
sulfuric acid.
This sulfuric acid is the
main pollutant in acid rain.
Natural rain is slightly acidic due
to dissolved carbon
dioxide.
Natural rain has a pH of 5·5, acid rain has a
pH of 4.
The second most important pollutant in acid
rain is nitric
acid - see next
page.
Acid
rain kills trees.
It runs into rivers and gathers in lakes.
Eventually, lakes become too acidic, and plants and fish begin
to die.
Acid rain
reacts with limestone
and damages limestone buildings.
Powdered limestone or slaked lime can be
added to soils or lakes
to make them less acidic. It would be better if we could avoid or reduce
pollutant gas
emissions in the first
place.
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