# A student is investigating how the temperature of water changes when it is heated. They record the temperature every 30 seconds. Explain how the student should ensure their results are reliable and how they should identify and deal with any anomalous results.

> OCR A-Level Chemistry A (H432) — 1.1 Practical skills assessed · Explain · 5 marks

> A student heats 100 cm³ of water and records the temperature at 30-second intervals. They want to make sure their investigation produces reliable results.

## Mark scheme (5 marks)

1. The student should repeat the experiment (at least three times) to obtain repeat readings
2. Calculate a mean (average) from the repeat readings to improve reliability
3. An anomalous result is one that does not fit the pattern/trend of the other results
4. Anomalous results should be identified by comparing each result to the others / to the overall trend
5. Anomalous results should be excluded from the calculation of the mean / the experiment should be repeated to replace the anomalous result

## Key terms

- [reliable](https://www.gradenine.co.uk/glossary/reliable)
- [anomalous result](https://www.gradenine.co.uk/glossary/anomalous-result)

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](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-is-investigating-how-the-cbdb6003) · Published by Druglandscape Ltd.