# Explain what is meant by a reversible reaction reaching equilibrium, and describe what happens to the rate of the forward and reverse reactions at equilibrium.

> AQA GCSE Chemistry (8462) — 4.6.2 Reversible reactions and dynamic equilibrium · Explain · 4 marks

## Mark scheme (4 marks)

1. A reversible reaction is one where the products can react to re-form the original reactants / the reaction can go in both directions.
2. Equilibrium is only reached when the reaction occurs in a closed system / apparatus that prevents reactants or products from escaping.
3. At equilibrium the forward reaction and the reverse reaction occur at exactly the same rate.
4. The concentrations of reactants and products remain constant / do not change at equilibrium.

## Key terms

- [reversible reaction](https://www.gradenine.co.uk/glossary/reversible-reaction)
- [equilibrium](https://www.gradenine.co.uk/glossary/equilibrium)
- [reverse reaction](https://www.gradenine.co.uk/glossary/reverse-reaction)

## 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/explain-what-is-meant-by-a-c2eeef0b) · Published by Druglandscape Ltd.