A-LevelChemistryReaction kineticsFeb/Mar 2017Paper 1 Q101 Mark
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?
A[Graph showing concentration of MnO₄⁻ decreasing slowly at first, then more rapidly, then levelling off.]
B[Graph showing concentration of MnO₄⁻ decreasing rapidly from the start, then levelling off.]
C[Graph showing concentration of MnO₄⁻ decreasing very slowly at first, then rapidly, then levelling off.]
D[Graph showing concentration of MnO₄⁻ increasing.]
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The correct answer is B. This question tests the candidate's understanding of reaction kinetics within the Chemistrysyllabus. The examiner's mark scheme requires...
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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...
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