# Methanol is manufactured industrially using the following reversible reaction carried out at high pressure and a temperature of around 250 °C in the presence of a copper-based catalyst:

CO(g) + 2H₂(g) ⇌ CH₃OH(g)     ΔH = −90 kJ/mol

Explain the effect on the position of equilibrium, and on the yield of methanol, of (i) increasing the pressure and (ii) increasing the temperature. In your answer, refer to Le Chatelier's principle.

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

## Mark scheme (5 marks)

1. States Le Chatelier's principle: when a system at equilibrium is subjected to a change, the equilibrium shifts to oppose that change.
2. Increasing pressure shifts the equilibrium to the right / towards the side with fewer moles of gas.
3. Therefore increasing pressure increases the yield of methanol.
4. Increasing temperature shifts the equilibrium to the left because the forward reaction is exothermic, so the system opposes the increase in temperature by favouring the endothermic (reverse) reaction.
5. Therefore increasing temperature decreases the yield of methanol.

## Key terms

- [Le Chatelier's principle](https://www.gradenine.co.uk/glossary/le-chatelier-s-principle)
- [position of equilibrium](https://www.gradenine.co.uk/glossary/position-of-equilibrium)
- [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/methanol-is-manufactured-industrially-using-the-86a2d756) · Published by Druglandscape Ltd.