# A student adds a small piece of marble (calcium carbonate) to excess hydrochloric acid. The reaction produces carbon dioxide gas. Explain how increasing the surface area of the marble, by breaking it into smaller pieces, increases the rate of this reaction.

> Eduqas GCSE Chemistry — C6 Rate and extent of chemical change · Explain · 4 marks

## Mark scheme (4 marks)

1. Breaking the marble into smaller pieces increases the surface area exposed to the acid
2. More reactant particles are exposed / available at the surface for collisions
3. This leads to a greater frequency of successful collisions
4. Therefore the rate of reaction increases

## Key terms

- [surface area](https://www.gradenine.co.uk/glossary/surface-area)

## 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)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-adds-a-small-piece-10a884f6) · Published by Druglandscape Ltd.