Case study·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
Three acids A, B and C are ethanoic acid, chloroethanoic acid and benzoic acid. Their acidity is compared using conjugate-base stability and substituent effects.
Total: 3 marks
(a) Which acid is strongest? (1 mark)
(b) Why is ethanoic acid weaker than chloroethanoic acid? (1 mark)
(c) Which test can distinguish these acids from neutral aldehydes and ketones by gas evolution? (1 mark)
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