# Crude oil is separated by fractional distillation. Describe how fractional distillation works and explain why the different hydrocarbons in crude oil can be separated by this process.

> Edexcel GCSE Chemistry (1CH0) — 8.1 Fuels · Describe · 4 marks

> Crude oil is a finite resource formed from the remains of ancient marine organisms. It is a mixture of many different hydrocarbon molecules that must be separated before they can be used as fuels.

## Mark scheme (4 marks)

1. The crude oil mixture is heated / vaporised
2. The vapours rise up a fractionating column where there is a temperature gradient (hotter at the bottom, cooler at the top)
3. Different hydrocarbons have different boiling points
4. Each hydrocarbon condenses and is collected at the part of the column that matches its boiling point / where it cools enough to condense

## Key terms

- [fractional distillation](https://www.gradenine.co.uk/glossary/fractional-distillation)
- [hydrocarbons](https://www.gradenine.co.uk/glossary/hydrocarbons)
- [crude oil](https://www.gradenine.co.uk/glossary/crude-oil)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/crude-oil-is-separated-by-fractional-8efc4c86) · Published by Druglandscape Ltd.