# A student wants to find out whether the mass of a catalyst affects the rate of decomposition of hydrogen peroxide solution. Describe how the student could carry out a fair and reliable investigation to test this.

> Cambridge International IGCSE Chemistry (0620) — 12.1 Experimental design · Describe · 4 marks

## Mark scheme (4 marks)

1. Measure the volume of oxygen gas produced as an indicator of the rate of reaction
2. Change only the mass of catalyst while keeping all other variables constant
3. Use at least three different masses of catalyst to identify a trend
4. Repeat each experiment and calculate a mean to improve reliability

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-wants-to-find-out-ff608c58) · Published by Druglandscape Ltd.