# A sports drink manufacturer produces a new energy drink. A food scientist wants to find out whether the orange colouring used in the drink is a pure substance or a mixture of dyes. She uses paper chromatography to investigate the colouring, using water as the solvent. After the experiment, the colouring produces three separate spots on the paper. Explain what this result tells the food scientist about the orange colouring, and describe the role of the mobile phase and stationary phase in causing the spots to separate.

> Eduqas GCSE Chemistry — 1.2 Atomic structure and the periodic table · Explain · 4 marks

## Mark scheme (4 marks)

1. The orange colouring is a mixture (not a pure substance) because it produces more than one spot
2. A pure substance would produce only one spot (in all solvents)
3. The mobile phase (water/solvent) moves through the paper carrying the dyes with it
4. The dyes separate because they have different solubilities in the mobile phase / interact differently with the stationary phase (paper), so they travel different distances up the paper

## Key terms

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

## 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-sports-drink-manufacturer-produces-a-a02bb44b) · Published by Druglandscape Ltd.