What topic does this question test?

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

Which exam paper is this question from?

This question appeared in the Cambridge A-Level Chemistry May/June 2019 examination, Paper 1 Variant 2 (9701_s19_qp_12.pdf).

A-LevelChemistryReaction kineticsMay/June 2019Paper 1 Q11 Mark

The Boltzmann distribution of molecular energies in a sample of aqueous hydrogen peroxide at room temperature is shown. [Figure 1.1] Which diagram shows the Boltzmann distribution of molecular energies of aqueous hydrogen peroxide maintained at room temperature when a catalyst, manganese(IV) oxide, is added?

ABoltzmann distribution curve with peak at the original energy and original height, but with the activation energy line shifted to a lower energy, resulting in a larger shaded area of molecules with sufficient energy.

BBoltzmann distribution curve with peak shifted to a lower energy and a higher peak height, and with the activation energy line shifted to a lower energy than in the original diagram, resulting in a larger shaded area of molecules with sufficient energy.

CBoltzmann distribution curve with peak shifted to a higher energy and a lower peak height, and with the activation energy line shifted to a higher energy than in the original diagram, resulting in a larger shaded area of molecules with sufficient energy.

DBoltzmann distribution curve with peak at the original energy and original height, and with the activation energy line at its original position, but with a larger shaded area of molecules with sufficient energy.

✓ Correct Answer

The correct answer is B: Boltzmann distribution curve with peak shifted to a lower energy and a higher peak height, and with the activation energy line shifted to a lower energy than in the original diagram, resulting in a larger shaded area of molecules with sufficient energy.

📋 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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