# A student wants to separate crude oil into its different fractions. Explain how fractional distillation can be used to do this.

> WJEC A-Level Chemistry (Wales) — 1.5 Energetics · Explain · 5 marks

> Crude oil is a mixture of many hydrocarbons with different boiling points. Fractional distillation is used in industry to separate crude oil into useful fractions.

## Mark scheme (5 marks)

1. Crude oil is heated / the mixture is heated so that it evaporates / vaporises
2. The hydrocarbons / fractions have different boiling points
3. The vapour rises up the fractionating column and condenses at different levels / temperatures
4. Each fraction is tapped off / collected at a different level of the fractionating column
5. Each fraction contains molecules with a similar number of carbon atoms / similar boiling points

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" 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/a-student-wants-to-separate-crude-abcdd6d3) · Published by Druglandscape Ltd.