5.10 Understand that incomplete combustion of fuels may produce carbon monoxide and explain that carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen

Usually hydrogens combust with oxygen to give carbon dioxide and and water, like so:

• Hydrocarbons + oxygen > carbon dioxide + water

However, if there is not enough oxygen, resulting in an incomplete combustion, the following reaction will be produced:

• Hydrocarbons + oxygen > carbon monoxide + carbon + water

Carbon monoxide is poisonous because it bonds with haemoglobin in the blood instead of oxygen, meaning that the oxygen isn't carried around the body