Can you guess what is common in rusting or iron, burning coal and the flame of candle? They all undergo a chemical reaction known as combustion. Combustion is a chemical reaction that occurs in the presence of a fuel and an oxidizing agent that produces energy, usually in the form of heat and light.
What we call as ‘burning’ is really a combustion reaction. In fact combustion is one of the first chemical reactions intentionally harnessed by humans. Any reaction that involves reaction with oxygen is called oxidation reaction. In the combustion of hydrocarbon with oxygen, typically carbon dioxide and water are produced.
CH4+2O2 → CO2+2H2O+Heat energy
(Hydrocarbon) + (Oxygen) → (Carbon dioxide) (Water)
All combustion reactions are exothermic; that is they release heat.
The minimum temperature at which a substance catches fire and burns is called its ignition temperature.
A substance will not catch fire and burn if its temperature is lower than its ignition temperature. Different substances have different ignition temperatures.
Substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances. E.g. Petrol. Alcohol, LPG (Liquefied Petroleum Gas), CNG (Compressed Natural Gas), etc.