# A student performs paper chromatography on two paint samples, Paint X and Paint Y, using the same solvent. Paint X produces one spot and Paint Y produces three spots. Explain what these results tell the student about the composition of each paint sample, and explain how the Rf value of a spot could be used to help identify one of the components.

> AQA GCSE Chemistry (8462) — 4.8.1 Purity, formulations and chromatography · Explain · 4 marks

## Mark scheme (4 marks)

1. Paint X is a pure substance / contains only one compound / is not a mixture
2. Paint Y is a mixture / contains three different compounds / components
3. The Rf value is the distance moved by the substance divided by the distance moved by the solvent
4. The Rf value can be compared to known / reference Rf values (in the same solvent) to identify the compound

## Key terms

- [Rf value](https://www.gradenine.co.uk/glossary/rf-value)
- [chromatography](https://www.gradenine.co.uk/glossary/chromatography)

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](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-performs-paper-chromatography-on-a19c298a) · Published by Druglandscape Ltd.