A-LevelChemistryReaction kineticsOct/Nov 2013Paper 1 Q51 Mark

An autocatalytic reaction is a reaction in which one of the products catalyses the reaction. Which curve was obtained if the rate of reaction was plotted against time for an autocatalytic reaction?

Q: What topic does this question test?

This question tests Reaction kinetics in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

AGraph showing rate starting at zero, increasing, then levelling off.

BGraph showing rate starting at zero, increasing, then decreasing to a non-zero constant rate.

CGraph showing rate starting at zero, increasing to a maximum, then decreasing towards zero.

DGraph showing rate starting at a high value, decreasing, then levelling off at a non-zero constant rate.

✓ Correct Answer

The correct answer is C: Graph showing rate starting at zero, increasing to a maximum, then decreasing towards zero.

📋 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 Reaction kinetics in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2013 examination, Paper 1 Variant 2.

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