Specification Point 4.8:
Describe how the industrial process of fractional distillation separates crude oil into fractions
Specification Point 4.9:
Know the names and uses of the main fractions obtained from crude oil: refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

Fractional Distillation

Fractional distillation: To separate two or more liquids that are miscible with one another

Industrial process of fractional distillation:

fractional distillation crude oil

The process of fractional distillation to separate crude oil in a fractionating column

Explanation:

Fractional distillation is carried out in a fractionating column.

  • In the fractionating column, it is hot at the bottom and cool at the top.
  • Crude oil will enter the fractionating column and will be heated so vapours will rise and evaporate.
  • Vapours of hydrocarbons with very high boiling points will immediately turn into liquid and are tapped off at the bottom of the column.
  • Vapours of hydrocarbons with low boiling points will rise up the column and condense at the top to be tapped off.
  • The different fractions will condense at different heights according to their boiling points and will be tapped off as liquids. All the fraction are mixtures of different kinds of hydrocarbon.

To conclude the smaller hydrocarbons are collected at the top of the fractionating column as gases. The bigger hydrocarbons are collected at the lower sections of the fractionating column.

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.