# A pharmaceutical company makes two products: pure aspirin tablets and a cold-relief formulation. Explain why only the pure aspirin tablets would show a sharp melting point, and describe how paper chromatography could be used to confirm that the aspirin used in the cold-relief formulation is mixed with other substances.

> WJEC A-Level Chemistry (Wales) — 1.3 Chemical bonding · Explain and Describe · 5 marks

## Mark scheme (5 marks)

1. A pure substance melts at one specific/sharp temperature (not over a range)
2. The cold-relief formulation is a mixture, so it melts/boils over a range of temperatures (not at a single sharp point)
3. A formulation is a mixture designed for a particular use, made up of exact quantities of pure substances (accept: the cold-relief product contains more than one substance mixed together)
4. In paper chromatography, the solvent (mobile phase) carries the substances up the paper (stationary phase) and different substances travel different distances / separate into different spots
5. If more than one spot is produced, this confirms the aspirin sample is mixed with other substances / is not pure (a pure compound produces only one spot)

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain and Describe" 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-pharmaceutical-company-makes-two-products-14f01c45) · Published by Druglandscape Ltd.