# The production of hydrogen iodide from hydrogen and iodine reaches a dynamic equilibrium in a sealed container according to the equation: H₂(g) + I₂(g) ⇌ 2HI(g). Explain what is meant by a dynamic equilibrium, and predict and explain what would happen to the yield of hydrogen iodide if the temperature is increased, given that the forward reaction is exothermic.

> Edexcel A-Level Chemistry (9CH0) — 10.1 Dynamic equilibria and Le Chatelier · Explain · 5 marks

> The production of hydrogen iodide from hydrogen and iodine reaches a dynamic equilibrium in a sealed container according to the equation: H₂(g) + I₂(g) ⇌ 2HI(g). The forward reaction is exothermic.

## Mark scheme (5 marks)

1. At dynamic equilibrium, the forward reaction and reverse reaction are both still occurring
2. The rate of the forward reaction equals the rate of the reverse reaction
3. Increasing temperature causes the equilibrium to shift in the direction of the endothermic reaction
4. The equilibrium shifts towards the reverse / left-hand side reaction
5. The yield of hydrogen iodide decreases

## Key terms

- [dynamic equilibrium](https://www.gradenine.co.uk/glossary/dynamic-equilibrium)
- [exothermic](https://www.gradenine.co.uk/glossary/exothermic)
- [yield](https://www.gradenine.co.uk/glossary/yield)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/the-production-of-hydrogen-iodide-from-5245bcd7) · Published by Druglandscape Ltd.