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A-LevelChemistryEquilibriaFeb/Mar 2024Paper 1 Q141 Mark

A mixture of hydrogen gas and iodine gas is placed in a reaction vessel of volume V at temperature T. The reaction H₂ + I₂ ⇌ 2HI is allowed to come to equilibrium. All substances remain in the gaseous state. Argon gas is then pumped into the reaction vessel. The temperature in the vessel is maintained at T. How are the rate of the forward reaction and the partial pressure of HI at equilibrium affected?

Arate of forward reaction: increased, partial pressure of HI at equilibrium: increased
Brate of forward reaction: increased, partial pressure of HI at equilibrium: unaffected
Crate of forward reaction: unaffected, partial pressure of HI at equilibrium: increased
Drate of forward reaction: unaffected, partial pressure of HI at equilibrium: unaffected

✓ Correct Answer

The correct answer is D: rate of forward reaction: unaffected, partial pressure of HI at equilibrium: unaffected

📋 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 Feb/Mar 2024 examination, Paper 1 Variant 2.

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