# A student wants to find out whether increasing the temperature of a reaction between marble chips and dilute hydrochloric acid increases the rate of reaction. Describe how the student could carry out a fair test to investigate this, including how the rate of reaction would be measured.

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

## Mark scheme (4 marks)

1. Keep one variable constant / identify a control variable (e.g. same mass/size of marble chips OR same concentration/volume of acid)
2. State that temperature is the independent variable / repeat the experiment at different temperatures
3. State a valid method to measure the rate of reaction (e.g. measure the volume of carbon dioxide gas collected in a set time OR measure the time taken to collect a fixed volume of gas)
4. State that the experiment should be repeated at each temperature (to improve reliability) OR that results at each temperature should be compared to draw a valid conclusion

## Key terms

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

## 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)
- [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-wants-to-find-out-209b3c7e) · Published by Druglandscape Ltd.