# Nitrogen monoxide and oxygen react together to form nitrogen dioxide. The reaction reaches a dynamic equilibrium in a closed container. Explain what is meant by the term 'dynamic equilibrium' and describe the effect on the position of equilibrium when the concentration of oxygen is increased.

> Edexcel GCSE Chemistry (1CH0) — 9.3 Dynamic equilibria, calculations involving volumes of gases (Chem only) · Explain · 4 marks

> The reaction between nitrogen monoxide and oxygen is shown below:
> 
> 2NO(g) + O₂(g) ⇌ 2NO₂(g)

## Mark scheme (4 marks)

1. At dynamic equilibrium, the forward reaction and the reverse reaction are both still occurring
2. The rate of the forward reaction equals the rate of the reverse reaction
3. Increasing the concentration of oxygen increases the rate of the forward reaction
4. The position of equilibrium shifts to the right, producing more nitrogen dioxide

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](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/nitrogen-monoxide-and-oxygen-react-together-49fb1e17) · Published by Druglandscape Ltd.