# A medicine manufacturer produces paracetamol tablets. A quality control chemist uses paper chromatography to check a batch of tablets for purity. The chemist spots a sample of the tablet contents onto chromatography paper alongside a sample of pure paracetamol and allows the solvent to travel up the paper. Explain how the chemist can use the results of this chromatography to determine whether the tablet sample contains only paracetamol or whether other substances are present.

> Eduqas A-Level Chemistry — 1.6 Kinetics · Explain · 5 marks

> Paper chromatography separates substances in a mixture based on how soluble each substance is in the mobile phase. A pure compound will produce a single spot in all solvents, whereas a mixture will separate into different spots.

## Mark scheme (5 marks)

1. The solvent (mobile phase) carries the substances up the paper (stationary phase)
2. Substances that are more soluble in the solvent travel further up the paper, so different substances separate into different spots
3. If the tablet sample is pure paracetamol, it will produce only one spot
4. The single spot from the tablet sample must be at the same height / same Rf value as the spot from the pure paracetamol reference sample
5. If the tablet sample produces more than one spot, it contains other substances / is not pure paracetamol

## Related

- [Revision notes for Eduqas A-Level Chemistry](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-medicine-manufacturer-produces-paracetamol-tablets-24fd5795) · Published by Druglandscape Ltd.