• Crude oil is a mixture of compounds called hydrocarbons. Many useful materials can be produced from crude oil.
•  It can be separated into different fractions using fractional distillation, and some of these can be used as fuels.

Alkanes

Crude oil forms naturally over millions of years from the remains of living things. Most of the compounds in crude oil are hydrocarbons. These are compounds that contain hydrogen and carbon atoms only, joined together by chemical bonds called covalent bonds. There are different types of hydrocarbon, but most of the ones in crude oil are alkanes.

The alkanes are a family of hydrocarbons that share the same general formula. This is:

C_nH_2n+2

The general formula means that the number of hydrogen atoms in an alkane is double the number of carbon atoms, plus two. For example, methane is CH₄ and ethane is C₂H₆.