Crude oil, which is thought to be the fossilised remains of forms of life which existed on earth many millions of years ago, is the major source of organic chemicals.
Crude oil is a mixture of hydrocarbons which belong to the alkane series.
The components of crude oil are separated by fractional distillation into fractions, which are used as different fuels. Alkanes with increasing numbers of carbon atoms have names are based on the Greek word for the number of carbon atoms in the chain of each molecule. From pentane onwards, approximately the next thirty alkanes in the series are liquids. Alkanes with even longer chains are waxy solids. Alkanes burn in oxygen to produce carbon dioxide and steam.