Process of Fractional Distillation
Chemistry: AQA GCSE Higher, topic 7.1.6
The Process of Fractional Distillation
Different-sized hydrocarbons have different boiling points. Fractional distillation separates hydrocarbons using their different boiling points. The steps of the process are:
Evaporation
- We evaporate the crude oil by heating it.
- Crude oil vapour is put into a fractionating column at the bottom and rises upwards.
Condensation
- The temperature is highest at the bottom of the column. Long-chain hydrocarbons condense at the bottom and are collected as liquids.
- Short-chain hydrocarbons have lower boiling points. They pass up the column and condense at lower temperatures nearer the top.
Collection
- The fractions are collected. They are then processed to create end products:
- Fuels (e.g. petrol, diesel) are a common end product.
- The petrochemical industry can use some fractions as feedstock (material used in an industrial process) to make products such as solvents, detergents, lubricants etc.
Test yourself on Process of Fractional Distillation
What is not an end product created from crude oil fractions?
What are the 3 steps in fractional distillation?
Fractional Distillation
Why do long-chain hydrocarbons condense at the bottom of the fractionating column?
A fraction is collected very close to the top of the fractionating column. What does this suggest about its hydrocarbon chain length compared with a fraction collected at the bottom?