Crude oil is separated into fractions by fractional distillation. Each fraction is a mixture of hydrocarbons with similar boiling points, and each has its own uses.
- Gases are used in domestic heating and cooking.
- Petrol is used as fuel for cars.
- Kerosene is used as fuel for aircraft.
- Diesel oil is used as fuel for some cars and trains.
- Fuel oil is used as fuel for large ships and in some power stations.
- Bitumen is used to surface roads and roofs.
Most of these fractions are burned as fuels, which is why crude oil is such an important source of energy. Bitumen is not burned. It is the thick, sticky substance left at the bottom of the fractionating column.