• Crude oil is separated by fractional distillation.
  • Crude oil is heated and the oil evaporates.
  • It then goes into the tower. As the vapours rise up the tower the temperature falls.
  • Different sized fractions condense at different heights because they have different boiling points.
  • Smaller molecules condense high up the tower. Larger molecules condense low down in the tower.
  • The fractions are collected.