Esters
Cambridge A-Level Chemistry (9701) · Unit 18: Carboxylic acids and derivatives · 7 flashcards
Esters is topic 18.2 in the Cambridge A-Level Chemistry (9701) syllabus , positioned in Unit 18 — Carboxylic acids and derivatives , alongside Carboxylic acids. In one line: Esters are produced by reacting a carboxylic acid with an alcohol. This requires a strong acid catalyst (.
Marked as A2 Level: examined at A Level in Paper 4 (A Level Structured Questions) and Paper 5 (Planning, Analysis and Evaluation). It is not tested on the AS-only papers (Papers 1, 2 and 3).
The deck below contains 7 flashcards — 2 definitions, 3 key concepts and 2 calculations — covering the precise wording mark schemes reward. Use the 2 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
What reagents and conditions are required for esterification
Esters are produced by reacting a carboxylic acid with an alcohol. This requires a strong acid catalyst (
What the Cambridge 9701 syllabus says
2025-2027 syllabus, in our words · A2 LevelWhat the syllabus expects you to be able to do in this topic, in plain English. For the exact wording, see the official syllabus (PDF).
- Recall how esters are made, with reagents and conditions: (a) a condensation reaction of an alcohol with a carboxylic acid, using concentrated H₂SO₄ as catalyst.
- Describe how esters are hydrolysed by heating, both with dilute acid and with dilute alkali.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9701 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
What reagents and conditions are required for esterification?
Esters are produced by reacting a carboxylic acid with an alcohol. This requires a strong acid catalyst (
Write a balanced equation for the formation of ethyl ethanoate from ethanol and ethanoic acid.
CH₃COOH + CH₃CH₂OH ⇌ CH₃COOCH₂CH₃ + H₂O. This is a reversible reaction and typically proceeds slowly without a catalyst.
Describe the process of acid hydrolysis of an ester.
Acid hydrolysis involves heating the ester with a dilute acid (
Describe the process of alkaline hydrolysis of an ester.
Alkaline hydrolysis involves heating the ester with a dilute alkali (
What products are formed from the alkaline hydrolysis of methyl propanoate?
Methanol (CH₃OH) and the sodium salt of propanoic acid (CH₃CH₂COO⁻Na⁺) are formed when methyl propanoate is heated with sodium hydroxide.
Why is alkaline hydrolysis of an ester considered irreversible, unlike acid hydrolysis?
Alkaline hydrolysis is essentially irreversible because the carboxylate salt formed is stable and does not readily react with the alcohol to reform the ester. The acid-base reaction to form the carboxylate is favored.
Write the general equation for ester hydrolysis using an acid catalyst.
RCOOR' + H₂O ⇌ RCOOH + R'OH, where R and R' are alkyl groups. The equilibrium can be shifted to the right by using a large excess of water.
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All Chemistry FlashcardsMore topics in Unit 18 — Carboxylic acids and derivatives
Esters sits alongside these A-Level Chemistry decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Esters deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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