# A student investigates the rate of reaction between marble chips (calcium carbonate) and hydrochloric acid. The student repeats the experiment using the same mass of marble chips but crushes them into a powder before adding the acid. Explain why crushing the marble chips into a powder increases the rate of reaction.

> Edexcel GCSE Chemistry (1CH0) — 7.1 Rates of reaction · Explain · 4 marks

## Mark scheme (4 marks)

1. Crushing the marble chips increases the surface area of the reactant
2. There are more exposed reacting particles (on the surface)
3. Collisions between reactant particles occur more frequently / there are more frequent collisions
4. There are more frequent successful collisions, so the rate of reaction increases

## Key terms

- [rate of reaction](https://www.gradenine.co.uk/glossary/rate-of-reaction)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](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-student-investigates-the-rate-of-90c4b91e) · Published by Druglandscape Ltd.