ACID RAIN Even nitrogen and oxygen react at the high temperatures found in a car’s engine, making poisonous nitrogen oxides. These also cause acid rain as nitric acid. Fuel often contains sulfur. When we burn fuel, the sulfur is oxidised forming toxic sulfur dioxide gas. If released into the atmosphere this eventually forms sulfuric acid, causing acid rain. Acid Rain kills trees and makes lakes too acidic. Acid rain reacts with limestone (CaCO3) buildings and statues.

Incomplete combustion If there is not enough oxygen when we burn fuel we get incomplete combustion. Poisonous carbon monoxide (CO) gas is formed. This binds more strongly than oxygen with red blood cells. Diesel engines use bigger hydrocarbon molecules than petrol. These do not burn completely and produce tiny unburnt particulates. These cause cancer and global dimming.

Cleaning up Modern cars are fitted with a catalytic converter. This turns dangerous carbon monoxide and nitrogen oxides into harmless carbon dioxide and nitrogen. Catalytic converters are very effective as they contain: Precious metal catalysts Large surface area Burning fossil fuels produces the greenhouse gas carbon dioxide. It traps heat in the earth’s atmosphere causing global warming. Filters in diesel engines trap particulates Sulfur is now removed from petrol and diesel. Power stations ‘scrub’ waste gases with calcium hydroxide to remove sulfur dioxide.

YOUR TASK Take one sheet of A3 paper and create a mindmap or poster of the problems of burning fuels and what we have done to reduce them. Key themes to include: Acid Rain, Global Warming, Global Dimming. Key words: Sulfur dioxide, nitrogen oxides, fossil fuels, particulates, asthma, cancer, carbon monoxides, catalytic converter, incomplete combustion.