Atmospheric Oxides
Chemistry: Cambridge International A Level, topic 2.5.7
Harmful Effects of Combustion
Combustion can cause the production of some nasty chemicals.
The internal combustion engine
- The combustion of alkanes powers our cars via the internal combustion engine.
- Common impurities from the internal combustion engine are:
- Nitrous oxides (NOx).
- Unburned hydrocarbons.
- Carbon monoxide.
- Nitrous oxides react to form ozone at ground level.
- Ozone irritates eyes and can cause lung damage.
Flue gases
- Flue gases are the gases that come out of chimneys. They are also produced as industrial waste.
- Flue gases often contain sulfur dioxide.
- Sulfur dioxide dissolves in water to make sulfuric acid. This then falls as acid rain, which destroys trees and vegetation.
Nitrous oxides & sulphur oxides
- Sulphur dioxide (SO2 causes acid rain. SO2 is oxidized to SO3. SO3 then reacts with water to form H2SO4.
- SO3 + H2O → H2SO4
- Nitrous oxides catalyse the formation of SO3, so contribute to acid rain:
- SO2 + NO2 → SO3 + NO
- NO2 is then regenrated through treating with atmospheric oxygen:
- NO + 1/2O2 → NO2
Removing these chemicals
- We can remove sulfur dioxide by reacting with calcium oxide or calcium carbonate.
- This is because sulfur dioxide is acidic and calcium oxide is basic. The balanced equation for the process is:
- CaO +SO2 → CaSO3
- Catalytic converters can remove unburned hydrocarbons and nitrous oxides from fuel.
Test yourself on Atmospheric Oxides
What can we use to remove unburned hydrocarbons and nitrous oxides?