A-LevelChemistryEquilibriaMay/June 2010Paper 1 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?

Q: What topic does this question test?

This question tests Equilibria in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

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

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

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Chemistry Question

Topic

This multiple-choice question tests Equilibria in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry May/June 2010 examination, Paper 1 Variant 2.

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