18.2 A2 Level

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.

Key definition

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 (

Example: concentrated sulfuric acid, H₂SO₄) and heating under reflux.

What the Cambridge 9701 syllabus says

Official 2025-2027 spec · A2 Level

These are the exact learning outcomes Cambridge sets for this topic. The candidate is expected to be able to do each of these on the relevant paper.

  1. recall the reaction (reagents and conditions) by which esters can be produced:
  2. describe the hydrolysis of esters by dilute acid and by dilute alkali and heat

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.

esters condensation reaction hydrolysis

Tips to avoid common mistakes in Esters

Definition Flip

What reagents and conditions are required for esterification?

Answer Flip

Esters are produced by reacting a carboxylic acid with an alcohol. This requires a strong acid catalyst (

Example: concentrated sulfuric acid, H₂SO₄) and heating under reflux.
Calculation Flip

Write a balanced equation for the formation of ethyl ethanoate from ethanol and ethanoic acid.

Answer Flip

CH₃COOH + CH₃CH₂OH ⇌ CH₃COOCH₂CH₃ + H₂O. This is a reversible reaction and typically proceeds slowly without a catalyst.

Key Concept Flip

Describe the process of acid hydrolysis of an ester.

Answer Flip

Acid hydrolysis involves heating the ester with a dilute acid (

Example: HCl or H₂SO₄). This breaks the ester bond, reforming the carboxylic acid and alcohol that it was originally made from. The reaction is the reverse of esterification.
Key Concept Flip

Describe the process of alkaline hydrolysis of an ester.

Answer Flip

Alkaline hydrolysis involves heating the ester with a dilute alkali (

Example: NaOH or KOH). This breaks the ester bond, forming the alcohol and the salt of the carboxylic acid. This is also known as saponification.
Definition Flip

What products are formed from the alkaline hydrolysis of methyl propanoate?

Answer Flip

Methanol (CH₃OH) and the sodium salt of propanoic acid (CH₃CH₂COO⁻Na⁺) are formed when methyl propanoate is heated with sodium hydroxide.

Key Concept Flip

Why is alkaline hydrolysis of an ester considered irreversible, unlike acid hydrolysis?

Answer Flip

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.

Calculation Flip

Write the general equation for ester hydrolysis using an acid catalyst.

Answer Flip

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.

More Chemistry flashcards

Browse every 9701 flashcard topic by syllabus area.

All Chemistry Flashcards
18.1 Carboxylic acids 19.1 Primary amines

More 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.

18.1 Carboxylic acids

7 flashcards

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.

What reagents and conditions are required for esterification
What products are formed from the alkaline hydrolysis of methyl propanoate

How to study this Esters deck

Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.