AS Level Chemistry chapter 18: Carboxylic acids and derivatives MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

44 exam-style questions on Carboxylic acids and derivatives, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

44 questions · 2 topics · 10 per test

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What chapter 18 covers

Ten Carboxylic acids and derivatives questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. 0.30 g of magnesium is added to excess aqueous ethanoic acid. What volume of hydrogen is produced at room conditions?

  1. A
    148 cm3
  2. B
    277 cm3
  3. C
    296 cm3
  4. D
    593 cm3
Show answer

Answer: C. Mg + 2CH3COOH → (CH3COO)2Mg + H2, so 0.30 / 24.3 = 0.0123 mol Mg gives 0.0123 mol H2, i.e. 296 cm3 at 24.0 dm3 mol−1. 277 cm3 uses 22.4 dm3; 148 and 593 use the wrong mole ratio.

2. 8.80 g of ethyl ethanoate (Mr 88.0) is completely hydrolysed. What mass of ethanol is formed?

  1. A
    2.30 g
  2. B
    6.00 g
  3. C
    8.80 g
  4. D
    4.60 g
Show answer

Answer: D. 8.80 ÷ 88.0 = 0.100 mol of ester, which gives 0.100 mol of ethanol (Mr 46.0) = 4.60 g. 6.00 g is the mass of ethanoic acid formed.

3. Which equation correctly represents the reaction of sodium with propanoic acid?

  1. A
    2CH3CH2COOH + 2Na → 2CH3CH2COONa + H2
  2. B
    CH3CH2COOH + Na → CH3CH2COONa + H2
  3. C
    2CH3CH2COOH + Na → (CH3CH2COO)2Na + H2
  4. D
    CH3CH2COOH + Na → CH3CH2COONa + H2O
Show answer

Answer: A. Sodium forms Na+, so the salt is CH3CH2COONa, and each acid molecule gives one H atom, so two acid molecules are needed per H2. The second equation is not balanced for hydrogen.

4. Each compound is heated under reflux with excess acidified potassium manganate(VII). Which one does not give a carboxylic acid?

  1. A
    propanal
  2. B
    propan-2-ol
  3. C
    butan-1-ol
  4. D
    ethanal
Show answer

Answer: B. Propan-2-ol is a secondary alcohol, so it is oxidised only as far as the ketone propanone. Aldehydes and primary alcohols are both oxidised to carboxylic acids under reflux.

5. Why does the hydrolysis of an ester by dilute acid not go to completion, while hydrolysis by dilute sodium hydroxide does?

  1. A
    acid hydrolysis is reversible, but in alkali the acid formed becomes a carboxylate ion that cannot react with the alcohol
  2. B
    the acid is used up during the hydrolysis
  3. C
    sodium hydroxide is a better catalyst than acid
  4. D
    esters are insoluble in dilute acid
Show answer

Answer: A. With acid, ester + water ⇌ acid + alcohol reaches equilibrium. In alkali the carboxylic acid is immediately converted to RCOO−, which cannot re-form the ester, so the reaction goes to completion.

6. Propyl ethanoate is heated under reflux with dilute sodium hydroxide. Excess dilute hydrochloric acid is then added to the cooled mixture. Why is the hydrochloric acid added?

  1. A
    to neutralise the propan-1-ol formed
  2. B
    to catalyse the hydrolysis of the ester
  3. C
    to reverse the hydrolysis and re-form the ester
  4. D
    to convert the ethanoate ions into ethanoic acid
Show answer

Answer: D. Alkaline hydrolysis gives sodium ethanoate and propan-1-ol; the strong acid protonates CH3COO− to give the free carboxylic acid. Propan-1-ol is neutral and does not need neutralising.

7. An ester has the structural formula CH3CH2CH2COOCH3. What is its name?

  1. A
    butyl methanoate
  2. B
    methyl propanoate
  3. C
    propyl ethanoate
  4. D
    methyl butanoate
Show answer

Answer: D. CH3CH2CH2CO– (four carbons, including the C=O carbon) comes from butanoic acid and –OCH3 from methanol, so it is methyl butanoate. Butyl methanoate, HCOOCH2CH2CH2CH3, reverses the two parts.

8. Which alcohol and carboxylic acid react to form ethyl methanoate, HCOOCH2CH3?

  1. A
    methanol and ethanoic acid
  2. B
    ethanol and methanoic acid
  3. C
    ethanol and ethanoic acid
  4. D
    methanol and methanoic acid
Show answer

Answer: B. In an ester name the alkyl group (ethyl) comes from the alcohol and the -oate part (methanoate) comes from the acid, so the reactants are ethanol and methanoic acid.

9. 6.00 g of ethanoic acid is heated with excess ethanol and a little concentrated sulfuric acid. 5.28 g of ethyl ethanoate (Mr 88.0) is obtained. What is the percentage yield?

  1. A
    46.0%
  2. B
    60.0%
  3. C
    71.4%
  4. D
    88.0%
Show answer

Answer: B. 0.100 mol of ethanoic acid (Mr 60.0) could give 0.100 mol (8.80 g) of ester; 5.28 / 8.80 × 100 = 60.0%. 88.0% divides the two masses directly and 46.0% uses the Mr of ethanol for the acid.

10. 0.0200 mol of ethanoic acid reacts completely with excess sodium carbonate. What volume of carbon dioxide is produced at room conditions?

  1. A
    0.120 dm3
  2. B
    0.240 dm3
  3. C
    0.480 dm3
  4. D
    0.0240 dm3
Show answer

Answer: B. 2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2. Two moles of acid give one mole of CO2: 0.0100 mol × 24.0 = 0.240 dm3.

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How many Carboxylic acids and derivatives MCQs are there?

44, each with the answer and a short explanation, across 2 topics: Carboxylic acids, Esters. Every chapter test draws ten of them, so you can take it many times.

Is the AS Level Chemistry chapter 18 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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