A-LevelChemistryEquilibriaMay/June 2019Paper 1 Q101 Mark
Ethyl ethanoate undergoes the following reaction. CH3CO2C2H5 + H2O ⇌ C2H5OH + CH3CO2H Kс = 0.27 Equal amounts of ethanoic acid and ethanol were mixed together and allowed to reach equilibrium. At equilibrium, the concentrations of both ethanoic acid and ethanol were 0.42 mol dm⁻³. What is the concentration of ethyl ethanoate at equilibrium?
A0.22 mol dm⁻³
B0.65 mol dm⁻³
C0.81 mol dm⁻³
D1.54 mol dm⁻³
✓ Correct Answer
The correct answer is C: 0.81 mol dm⁻³
📋 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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