# A food manufacturer produces a fruit drink by mixing water, sugar, and several different food colourings together. A student carries out paper chromatography on the fruit drink to investigate the food colourings it contains. The student finds that one of the spots produced matches the Rf value of a known pure food colouring, whilst another spot separates into three separate spots. Explain what the chromatography results tell the student about the food colourings in the fruit drink.

> Eduqas GCSE Chemistry — 1.3 Water · Explain · 4 marks

## Mark scheme (4 marks)

1. The spot that matches the known Rf value indicates that colouring is a pure substance / single compound
2. The Rf value can be used to identify the substance / substances with the same Rf value are the same compound
3. The spot that separates into three spots shows that colouring is a mixture / not a pure substance
4. The three components of the mixture separate because they have different Rf values / because they are differently distributed between the mobile phase and stationary phase / because they have different solubilities in the solvent

## Key terms

- [Rf value](https://www.gradenine.co.uk/glossary/rf-value)
- [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-food-manufacturer-produces-a-fruit-d2137f57) · Published by Druglandscape Ltd.