Oxidation of ethanedioate ions by acidified manganate(VII) ions is very slow at room temperature. 2MnO₄⁻ + 5C₂O₄²⁻ + 16H⁺ → 2Mn²⁺ + 10CO₂ + 8H₂O Mn²⁺ ions catalyse this reaction. Which graph shows how the concentration of acidified manganate(VII) ions varies after ethanedioate ions are added?
✓ Correct Answer
The correct answer is B: [Graph showing concentration of MnO₄⁻ decreasing rapidly from the start, then levelling off.]
📋 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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