# A reversible reaction takes place in a closed container. After some time, the system reaches equilibrium. A student adds more reactant to the closed container. Describe and explain what happens to the position of equilibrium.

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

## Mark scheme (4 marks)

1. The position of equilibrium shifts towards the products (forward reaction is favoured)
2. This is because the system acts to counteract the change / oppose the increase in concentration of reactant
3. The concentration of products increases / more products are formed until a new equilibrium is reached
4. The concentration of reactants decreases (compared to immediately after addition) as equilibrium is re-established

## Key terms

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

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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-reversible-reaction-takes-place-in-d074a7c0) · Published by Druglandscape Ltd.