A-LevelChemistryEquilibriaMay/June 2022Paper 1 Q141 Mark
Hydrogen and iodine can react reversibly to produce hydrogen iodide. The equation is shown. H₂(g) + I₂(g) ⇌ 2HI(g) 4.00 mol of hydrogen gas and X mol of iodine vapour are mixed in a sealed container of volume 1.00 dm³ at a temperature of 460 K. The system is allowed to reach equilibrium. The equilibrium mixture contains 2.00 mol of hydrogen iodide. The equilibrium constant, K_c, for the reaction at 460 K is 4.0. What is the value of X?
A0.50 mol
B1.17 mol
C1.33 mol
D2.50 mol
✓ Correct Answer
The correct answer is C: 1.33 mol
📋 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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