Combustion is defined as a process in which a compound is burned in the presence of oxygen to form subsequent products. The combustion of a hydrocarbon is one of the most important chemical reactions, and the energy given out is used to drive chemical engines in automobiles, gas stations etc. There are two types of combustion: Complete Combustion: All the bonds in a hydrocarbon molecule are broken down in excess of oxygen to form carbon dioxide and water. Incomplete Combustion: Incomplete combustion occurs when there is insufficient oxygen, so hydrocarbon is partially oxidised and lesser energy released. Carbon Monoxide and Water are the end-products formed.