Air
| Gas | Percentage in Air | Percentage in Inhaled Air | Percentage in Exhaled Air |
| Nitrogen | 79 | 79 | 79 |
| Oxygen | 20 | 20 | 17 |
| Argon | 0.9 | 1 (with other Inert Gases) | 1 (with other Inert Gases) |
| Carbon Dioxide | 0.03 | Trace | 4 |
| Others | 0.07 | – | – |
| Water | – | Variable | Saturated |
Fractional Distillation of Air – the main industrial method of preparation of pure oxygen and nitrogen
- Air is liquefied by compression and cooling to below the boiling point of both oxygen and nitrogen, so that most of the “air” becomes a
- The liquid “air” is allowed to warm slowly and the nitrogen (b.p. -195°C) boils off first and thus can be
- The oxygen (b.p. -183°C) boils off after the nitrogen and can then also be
| Pollutants | Cause | Effect | Solution |
| Sulphur Dioxide | Combustion of Sulphur (found in fossil fuels) | Forms acid rain when reacted with water in clouds | Scrubbing – converts SO2 to H2SO4 |
|
S(s) + O2(g) -> SO2(g) SO2(g) + H2O(l) -> H2SO3(aq) |
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| Nitrogen Oxides | Reaction between nitrogen and oxygen at high temp and pressure in motor vehicle engines | Contributes to Acid Rain and are a major component of photochemical smog | Catalytic Converters |
|
2N2(g) + 3O2(g) -> 2NO(g) + 2NO2(g) |
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| Carbon Monoxide | Incomplete combustion in motor vehicle engines | Strong bonds with haemoglobin, decreasing the amount of oxygen distributed around the body | Catalytic Converters |
| Lead | Combustion of petrol containing lead | Brain damage, nervous system problems | Catalytic Converters, using unleaded fuel |
Catalytic Converter –catalysts that convert poisonous exhaust fumes into harmless gasses in cars.
- The reduction catalyst uses platinum and rhodium to help reduce the NOx emissions by ripping the nitrogen atom out of the molecule, freeing the
2NO -> N2 + O2 / 2NO2 -> N2 + 2O2
- The oxidation catalyst removes the unburned hydrocarbons and carbon monoxide by burning them over a platinum and palladium
2CO + O2 -> 2CO2
- 2NO2 + 4CO -> 4CO2 + N2