Changing Pressure

Part of the Energy, Rates and Equilibrium section of Coddy's Chemistry journey. Lesson 29 of 35.

Higher pressure: the equilibrium shifts to the side with fewer gas molecules.

A piston pushed down on the Haber mixture: the equilibrium moves to the side with fewer gas molecules

Higher pressure favours the side with fewer gas molecules

Haber: 4 on the left, 2 on the right, so higher pressure gives more ammonia.

Equal gas molecules on both sides (H₂ + I₂ ⇌ 2HI): pressure has no effect.

Challenge

An engineer raises the pressure in a Haber reactor:

$\mathrm{N_2(g)} + 3\mathrm{H_2(g)} \rightleftharpoons 2\mathrm{NH_3(g)} \qquad \Delta H = -92\ \mathrm{kJ}$

Which way does the equilibrium shift?

Try it yourself

EquilibriumWhich way does it shift?

N₂(g)3 H₂(g)2 NH₃(g)

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Energy, Rates and Equilibrium

1Energy in Reactions

4Rates of Reaction

7Practice Problems

2Bond Energies

5Equilibrium

3Changes of State

6Changing an Equilibrium