A-LevelChemistryEquilibria9701/12 · May/June 2010 · Q111 Mark

The percentage of ammonia obtainable, if equilibrium were established during the Haber process, is plotted against the operating pressure for two temperatures, 400°C and 500 °C. Which diagram correctly represents the two graphs?

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AGraph shows %NH3 at equilibrium increasing with pressure; 400°C curve is above 500°C curve.

BGraph shows %NH3 at equilibrium decreasing with pressure; 500°C curve is above 400°C curve.

CGraph shows %NH3 at equilibrium increasing with pressure; 500°C curve is above 400°C curve.

DGraph shows %NH3 at equilibrium decreasing with pressure; 400°C curve is above 500°C curve.

✓ Correct answer

A: Graph shows %NH3 at equilibrium increasing with pressure; 400°C curve is above 500°C curve.

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Topic: Equilibria, A-Level Chemistry (syllabus 9701). Multiple choice, 1 mark.
Source: A-Level Chemistry, May/June 2010 Paper 1 Variant 2, question 11.

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