Revision Notes

Fractional Distillation

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 FractionBoiling PointUses of Fraction
Petroleum gases25ocBottled gas and chemicals
Gasoline40oc – 75ocPetrol
Naphtha75oc – 150ocChemicals
Kerosene150oc – 240ocJet Fuel
Diesel Oil220oc – 250ocDiesel Fuel
Lubricating Oil250oc – 350ocLubricants and chemicals
Fuel Oil350ocFuels for ships
Bitumenstays solid/liquidRoads and Roofing Felt
The products of fractional distillation