# A student investigates the rate of reaction between marble chips (calcium carbonate) and hydrochloric acid. She carries out two experiments using the same mass of marble chips and the same volume and concentration of acid, but in one experiment she uses large marble chips and in the other she uses small marble chips. Explain why the experiment using small marble chips produces a faster rate of reaction.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 3.2 Rates of reaction · Explain · 4 marks

## Mark scheme (4 marks)

1. Small marble chips have a greater (total) surface area (than large chips)
2. There are more exposed reacting particles (at the surface)
3. Collisions between reactant particles occur more frequently / there are more frequent collisions
4. There is a higher rate of 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 Pearson Edexcel International GCSE Chemistry (4CH1)](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-97011a70) · Published by Druglandscape Ltd.