A-LevelChemistryChemical energeticsOct/Nov 2014Paper 1 Q31 Mark
Ethanol is increasingly being used as a fuel for cars. The standard enthalpy change of formation of carbon dioxide is –393 kJ mol⁻¹. The standard enthalpy change of formation of water is –286 kJ mol⁻¹. The standard enthalpy change of formation of ethanol is –277 kJ mol⁻¹. What is the standard enthalpy change of combustion of ethanol?
A-1921 kJ mol⁻¹
B-1367 kJ mol⁻¹
C-956 kJ mol⁻¹
D-402 kJ mol⁻¹
✓ Correct Answer
The correct answer is B: -1367 kJ mol⁻¹
📋 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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