# A paint manufacturer produces a green paint by mixing together two pigments, one blue and one yellow. A student carries out paper chromatography on the green paint using a single solvent. After the experiment, only one spot is visible on the chromatography paper. Explain what this result tells the student about the green paint, and describe what the student would expect to see if the green paint were a mixture of the two pigments.

> Eduqas GCSE Chemistry — 1.4 The ever-changing Earth · Explain · 4 marks

> A paint manufacturer produces a green paint by mixing together two pigments, one blue and one yellow. A student carries out paper chromatography on the green paint using a single solvent. After the experiment, only one spot is visible on the chromatography paper.

## Mark scheme (4 marks)

1. A single spot indicates the green paint behaves as a pure substance / contains only one compound
2. This suggests the two pigments are not present as separate substances / the paint is not a mixture of two pigments
3. If it were a mixture of two pigments, two separate spots would be visible on the paper
4. The spots would appear at different heights / positions because the pigments have different solubilities in the mobile phase / solvent

## Key terms

- [paper chromatography](https://www.gradenine.co.uk/glossary/paper-chromatography)
- [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-paint-manufacturer-produces-a-green-316e59ad) · Published by Druglandscape Ltd.