A-LevelChemistryEquilibriaFeb/Mar 2021Paper 1 Q311 Mark
A sample of 17.15 mol HI(g) is in dynamic equilibrium with 2.27 mol H₂(g) and 2.84 mol I₂(g) in a volume of 1 m³ at 764 K and 141 kPa. H₂(g) + I₂(g) ⇌ 2HI(g) Two equilibrium constants, Kc and Kp, can be calculated for this mixture. Which statements about the equilibrium constants for this mixture are correct? 1 neither Kc nor Kp has any units 2 Kc = 45.6 3 Kc > Kp
A1, 2 and 3 are correct
B1 and 2 only are correct
C2 and 3 only are correct
D1 only is correct
✓ Correct Answer
The correct answer is B: 1 and 2 only are correct
📋 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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