A-LevelChemistryChemical energeticsOct/Nov 2016Paper 1 Q21 Mark
The diagram shows the pathways of a reaction, with and without a catalyst. [Figure showing energy profile diagram] Which letter represents the overall energy change for the reaction?
AActivation energy of the first step of the uncatalysed reaction.
BActivation energy of the uncatalysed reaction (from reactants to highest transition state).
COverall enthalpy change of the reaction (from reactants to products).
DActivation energy of the catalysed reaction (from reactants to catalysed transition state).
✓ Correct Answer
The correct answer is C. This question tests the candidate's understanding of chemical energetics within the Chemistrysyllabus. The examiner's mark scheme requires...
📋 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...
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