# Ethanol vapour can be produced by the reaction of ethene with steam in a closed container. The equation for the reaction is: C₂H₄(g) + H₂O(g) ⇌ C₂H₅OH(g). The reaction reaches equilibrium at a constant temperature. Explain how the equilibrium constant Kp for this reaction would change, if at all, if (i) the total pressure is increased at constant temperature, and (ii) the temperature is increased. In each case justify your answer.

> AQA A-Level Chemistry (7405) — 3.1.10 Equilibrium constant Kp (A-Level only) · Explain · 5 marks

## Mark scheme (5 marks)

1. Kp does not change when pressure is increased (at constant temperature)
2. Kp only changes when temperature changes / Kp is only affected by temperature
3. The forward reaction is exothermic (so increasing temperature favours the reverse reaction)
4. Increasing temperature shifts the equilibrium position to the left / towards reactants
5. Kp decreases when temperature is increased (because the equilibrium shifts to the left, giving a lower proportion of products)

## Key terms

- [equilibrium constant Kp](https://www.gradenine.co.uk/glossary/equilibrium-constant-kp)
- [closed container](https://www.gradenine.co.uk/glossary/closed-container)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/ethanol-vapour-can-be-produced-by-0b914513) · Published by Druglandscape Ltd.