Skip to main content
A-LevelChemistryChemical energeticsMay/June 2025Paper 1 Q131 Mark

Under certain conditions, CCl4 and H2O react as shown. The activation energy for the reaction is +62 kJ mol⁻¹. CCl4 + 2H2O → CO2 + 4HCl ΔH = −61.5 kJ mol⁻¹ Which enthalpy profile diagram best fits this reaction?

ADiagram showing an exothermic reaction profile with the activation energy barrier above the reactants.
BDiagram showing an endothermic reaction profile with the activation energy barrier above the reactants.
CDiagram showing an exothermic reaction profile with a larger activation energy barrier above the reactants than option A.
DDiagram showing an endothermic reaction profile with the activation energy barrier above the reactants.

✓ Correct Answer

The correct answer is D: Diagram showing an endothermic reaction profile with the activation energy barrier above the reactants.

📋 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.

🔒

Unlock the Examiner's Analysis

Sign up for free to reveal the full examiner report, trap analysis, and mark scheme breakdown for this question.

Sign Up Free to Unlock →

Join thousands of Cambridge students already using Oracle Prep

About This A-Level Chemistry Question

Topic

This multiple-choice question tests Chemical energetics in A-Level Chemistry (syllabus code 9701). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Chemistry May/June 2025 examination, Paper 1 Variant 2.

Practice on Oracle Prep

Oracle Prep provides AI-powered practice for all Cambridge O-Level and A-Level subjects. Our platform includes topic predictions with 87.7% accuracy, AI essay grading, and a comprehensive question bank spanning 25 years of past papers across 29 subjects.

Related Chemistry Questions

© 2026 Oracle Prep — The AI-Powered Cambridge Exam Engine