# A paint manufacturer produces a decorative wall paint by mixing several pure substances together in carefully measured quantities. Explain why this wall paint is described as a formulation and not a pure substance, and describe how paper chromatography could be used to show that the coloured pigment in the paint is a mixture rather than a pure substance.

> Eduqas A-Level Chemistry — 1.1 Atoms, molecules and stoichiometry · Explain · 5 marks

> A paint manufacturer produces a decorative wall paint by mixing several pure substances together in carefully measured quantities to give the product specific properties.

## Mark scheme (5 marks)

1. A formulation is a mixture designed for a particular use, made from exact/carefully measured quantities of pure substances
2. The paint is not a pure substance because it contains more than one compound/element that are not chemically bonded/combined together
3. A spot of the pigment is placed on paper (the stationary phase) above a solvent (the mobile phase)
4. The solvent (mobile phase) travels up the paper, carrying the components of the pigment at different speeds/distances because they have different solubilities in the solvent
5. A mixture will produce more than one spot on the paper, whereas a pure substance produces only a single spot, so multiple spots confirm the pigment is a mixture

## Key terms

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

## 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-paint-manufacturer-produces-a-decorative-678e2a7a) · Published by Druglandscape Ltd.