Fractional Distillation-

• Fractional distillation is used to separate crude oil into simpler, more useful mixtures
• This method is possible because different hydrocarbons have different boiling points
• During the fractional distillation of crude oil:

  • Heated crude oil enters near the bottom of a tall fractionating column, which is hot at the bottom and gets cooler towards the top
  • Vapours from the oil rise through the column
  • Vapours condense when the temperature of the column is cool enough
  • Liquids are led out of the column at different heights
• Some hydrocarbons with low boiling points leave the column as gases

  • Some hydrocarbons with high boiling points leave the column as hot liquid bitumen
• The different, useful mixtures separated from crude oil are called fractions because they are only part of the original crude oil