Fractional distillation is the process of heating up a mixture containing different substances with different boiling points, and drawing the different fractions off as they each boil and liquify at its own level. Crude oil contains a lot of useful substances that can be used for different purposes.
Each fraction is not a pure compound but is a mixture of different alkanes with similar boiling points. Fractional distillation is used because the substances in crude oil are miscible (which means that they mix) therefore they do not separate out into layers. The following table shows the products of fractional distillation:
| Name of Fraction | Boiling Point | Uses of Fraction |
| Petroleum gases | 25oc | Bottled gas and chemicals |
| Gasoline | 40oc – 75oc | Petrol |
| Naphtha | 75oc – 150oc | Chemicals |
| Kerosene | 150oc – 240oc | Jet Fuel |
| Diesel Oil | 220oc – 250oc | Diesel Fuel |
| Lubricating Oil | 250oc – 350oc | Lubricants and chemicals |
| Fuel Oil | 350oc | Fuels for ships |
| Bitumen | stays solid/liquid | Roads and Roofing Felt |