 In this video you are going to learn what combustion is, the difference between complete and incomplete combustion, the products of the two types of combustion and the effects of the products of combustion. Combustion is burning, usually in air which is all around us or oxygen. It's an exothermic reaction which means it gives out heat. A fuel stores potential energy that can be released as heat when we burn the fuel. An example of a fuel is natural gas or methane. This is the fuel we burn to heat up our food. Methane, like other hydrocarbon fuels such as petrol, can undergo either complete or incomplete combustion. When methane undergoes complete combustion, that is in a plentiful supply of air, it produces carbon dioxide and water, as shown by the equation, CH4 gas plus 202 gas gives CO2 gas plus 2H2O gas. When methane undergoes incomplete combustion, that's in a limited supply of air, it produces either carbon monoxide and water or carbon and water, as shown by the equations. 2CH4 gas plus 302 gas gives 2CO gas plus 4H2O gas. CH4 gas plus O2 gas gives C solid plus 2H2O gas. Now the effects of the products of combustion. Water vapour, as we all know, is harmless. Carbon dioxide is a greenhouse gas and contributes to global warming. Carbon monoxide, however, is toxic. It's colourless, odourless, tasteless, and so is called the silent killer. Carbon monoxide is often produced by faulty gas appliances. That's why it's important to have your gas fires and boilers regularly serviced. Unbaked carbon is a particulate and is a pollutant in the air. So to recap, combustion is burning, usually in air or oxygen. Complete combustion of hydrocarbons produces carbon dioxide and water. Complete combustion produces either carbon monoxide and water or carbon and water. And the products of combustion have various effects.