# The following reversible reaction reaches dynamic equilibrium in a closed container: N₂O₄(g) ⇌ 2NO₂(g). The forward reaction is endothermic. Explain what happens to the equilibrium position and the concentration of NO₂ when the temperature is increased.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 3.3 Reversible reactions and equilibria · Explain · 4 marks

> Dinitrogen tetroxide, N₂O₄, is a colourless gas that decomposes into brown nitrogen dioxide, NO₂, in a reversible reaction. When the system reaches dynamic equilibrium in a closed container, both gases are present at constant concentrations.

## Mark scheme (4 marks)

1. An increase in temperature shifts the equilibrium position in the direction of the endothermic reaction
2. The equilibrium shifts to the right / towards the products because the forward reaction is endothermic and absorbs the extra heat energy
3. The concentration of NO₂ increases
4. At the new equilibrium the concentrations of reactants and products remain constant again (but at different values)

## Key terms

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

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- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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