# A student is given two ink samples, ink A and ink B. The student uses paper chromatography to investigate whether the inks are pure substances or mixtures. Ink A produces a single spot and ink B produces three spots. Explain what these results show about the composition of each ink, and explain how the mobile phase and stationary phase are involved in separating the components of ink B.

> AQA GCSE Chemistry (8462) — 4.8.3 Identification of ions by chemical and spectroscopic means (Chem only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Ink A is a pure substance because it produces only one spot (in this solvent)
2. Ink B is a mixture because it produces more than one spot / three spots
3. The mobile phase (solvent) carries the components of ink B up the paper
4. The components separate because they have different solubilities in the mobile phase / interact differently with the stationary phase, so they travel different distances

## Key terms

- [pure substance](https://www.gradenine.co.uk/glossary/pure-substance)
- [mixture](https://www.gradenine.co.uk/glossary/mixture)
- [mobile phase](https://www.gradenine.co.uk/glossary/mobile-phase)
- [stationary phase](https://www.gradenine.co.uk/glossary/stationary-phase)
- [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-is-given-two-ink-6e1e7024) · Published by Druglandscape Ltd.