# A food scientist is testing a new fruit squash drink to find out how many different colourings it contains. She uses paper chromatography to separate the mixture of colourings. Explain how paper chromatography separates the colourings in the drink and how the scientist could use the results to determine whether any of the colourings is a pure substance.

> Eduqas GCSE Chemistry — 1.1 The nature of substances and chemical reactions · Explain · 4 marks

## Mark scheme (4 marks)

1. The solvent (mobile phase) moves through/up the paper (stationary phase), carrying the colourings with it.
2. Colourings that are more soluble in the solvent travel further up the paper, separating the colourings from one another.
3. A pure colouring will produce only one spot on the chromatogram.
4. If a colouring produces more than one spot, it is a mixture / not a pure substance.

## Key terms

- [paper chromatography](https://www.gradenine.co.uk/glossary/paper-chromatography)
- [pure substance](https://www.gradenine.co.uk/glossary/pure-substance)
- [mixture](https://www.gradenine.co.uk/glossary/mixture)

## Related

- [Revision notes for Eduqas GCSE Chemistry](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-food-scientist-is-testing-a-54c3dd73) · Published by Druglandscape Ltd.