# A student adds a small piece of magnesium ribbon to dilute sulfuric acid at room temperature. The magnesium dissolves and bubbles of gas are produced. Explain why increasing the concentration of the sulfuric acid would increase the rate of this reaction.

> Edexcel A-Level Chemistry (9CH0) — Topic 4 Physical chemistry and transition elements · Explain · 5 marks

## Mark scheme (5 marks)

1. Increasing concentration means there are more acid particles (hydrogen ions / H⁺ ions) in the same volume
2. This leads to a greater frequency of collisions between acid particles and magnesium atoms
3. More collisions per unit time means more successful/effective collisions per unit time
4. Therefore the rate of reaction increases
5. Reference to activation energy: only collisions that have energy equal to or greater than the activation energy result in a reaction

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](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-adds-a-small-piece-740627ef) · Published by Druglandscape Ltd.