# A student investigates how four metals react with dilute hydrochloric acid. Potassium reacts violently, magnesium reacts quickly, iron reacts slowly, and copper shows no visible reaction. Explain what these observations tell us about the reactivity of these metals and how their reactivity is related to the formation of positive ions.

> AQA GCSE Chemistry (8462) — 4.4.1 Reactivity of metals · Explain · 4 marks

> A student investigates how four metals react with dilute hydrochloric acid. Potassium reacts violently, magnesium reacts quickly, iron reacts slowly, and copper shows no visible reaction.

## Mark scheme (4 marks)

1. Metals can be arranged in order of reactivity in a reactivity series, with potassium most reactive and copper least reactive (from the observations given).
2. The reactivity of a metal is related to its tendency to form positive ions.
3. Potassium (and magnesium / iron) reacts because it is more reactive than hydrogen, so it displaces hydrogen from the acid.
4. Copper does not react because it is less reactive than hydrogen and cannot displace hydrogen from the acid.

## Key terms

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

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](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-how-four-metals-66c299fc) · Published by Druglandscape Ltd.