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Carboxylic acids and their derivatives: WJEC A‑Level Chemistry questions

Every WJEC A-Level Chemistry exam question on 4.5 Carboxylic acids and their derivatives, 2016–2025, with its mark scheme and examiner’s report.

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1,204 questions

  1. Q5(b)(i)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 5(b)(i): Draw the structure of the compound produced when compound E reacts with an excess of aqueous sodium hydroxide. [1]

  2. Q6(c)(ii)

    Summer 2025 · Unit 4

    2 marks4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 6(c)(ii): Carbonyl dichloride reacts as an acid chloride and produces esters of carbonic acid when reacted with alcohols. O R O C O R An ester of carbonic acid has a rela

  3. Q7(c)

    Summer 2025 · Unit 4

    3 marks4.5 Carboxylic acids and their derivatives4.4 Aldehydes and ketones
    The whole paper ↗
    Summer 2025 Unit 4, question 7(c): Each of the four compounds whose formulae are shown below are isomers. Compound Formula O R C OCH3 O H3C C S OH O CH3O C T H O HO C U CH3 Select the compound th

  4. Q8(c)(iv)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 8(c)(iv): In the body an enzyme converts L-dopa into dopamine by a decarboxylation reaction. HO NH2 HO dopamine Use this information to help you complete the equation for

  5. Q9(a)(i)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 9(a)(i): State reagent(s) that can be used for stage 1 [1]

  6. Q9(a)(ii)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 9(a)(ii): State the type of reaction occurring in stage 1 [1]

  7. Q9(a)(iii)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 9(a)(iii): One way of carrying out stage 2 is to react benzoic acid with phosphorus(V) chloride. Explain why the yield of benzoyl chloride, C6H5COCl, will be lower if mois

  8. Q9(a)(iv)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 9(a)(iv): In stage 3 benzamide is produced from benzoyl chloride by its reaction with ammonia. Suggest the structure of the compound produced if benzoyl chloride reacts w

  9. Q9(a)(v)

    Summer 2025 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2025 Unit 4, question 9(a)(v): In the reaction sequence opposite, benzamide is made from benzoic acid via the acid chloride, benzoyl chloride. It can be made from benzoic acid by a different

  10. Q7(d)(ii)

    Summer 2024 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2024 Unit 4, question 7(d)(ii): State what is seen when compound J reacts with sodium hydrogencarbonate solution. [1]

  11. Q9(a)(i)

    Summer 2024 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2024 Unit 4, question 9(a)(i): Balance the equation for the first stage of this process. [1] COOC4H9 C4H9OH + CO + O2 + H2O COOC4H9

  12. Q9(e)

    Summer 2024 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2024 Unit 4, question 9(e): Decarboxylation occurs when carboxylic acids are heated with sodalime. State the name of the organic compound produced when 4-ethylbenzenecarboxylic acid is hea

  13. Q11(a)(i)

    Summer 2024 · Unit 4

    2 marks4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2024 Unit 4, question 11(a)(i): In the first stage adipamide is hydrolysed using aqueous sodium hydroxide, giving disodium hexanedioate as one of the products. Complete and balance the equatio

  14. Q7(a)

    Summer 2023 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 7(a): Reagent F is . [1]

  15. Q7(b)

    Summer 2023 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 7(b): Give the structure of Compound G. [1]

  16. Q8(a)(ii)

    Summer 2023 · Unit 4

    4 marks4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 8(a)(ii): Sorbic acid and its salts, for example sodium sorbate, have important uses as antimicrobial agents in food preservation. Some moulds are, however, able to detox

  17. Q9(a)(i)

    Summer 2023 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 9(a)(i): State the type of reaction occurring. [1]

  18. Q9(b)(i)

    Summer 2023 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 9(b)(i): The acid chloride, benzene-1,4-dicarbonyl dichloride, ClOC C6H4 COCI is made by reacting benzene-1,4-dicarboxylic acid with phosphorus(V) chloride. The other pr

  19. Q9(c)(i)

    Summer 2023 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 9(c)(i): State the name of reagent(s) A. [1]

  20. Q9(c)(ii)

    Summer 2023 · Unit 4

    1 mark4.5 Carboxylic acids and their derivatives
    The whole paper ↗
    Summer 2023 Unit 4, question 9(c)(ii): State the name of reagent(s) B. [1]
All 49 questions on Carboxylic acids and their derivatives, as a list
  1. Summer 2025, Unit 4, Q5(b)(i) (1 mark): Draw the structure of the compound produced when compound E reacts with an excess of aqueous sodium hydroxide. [1]
  2. Summer 2025, Unit 4, Q6(c)(ii) (2 marks): Carbonyl dichloride reacts as an acid chloride and produces esters of carbonic acid when reacted with alcohols. O R O C O R An ester of carbonic acid has a rela
  3. Summer 2025, Unit 4, Q7(c) (3 marks): Each of the four compounds whose formulae are shown below are isomers. Compound Formula O R C OCH3 O H3C C S OH O CH3O C T H O HO C U CH3 Select the compound th
  4. Summer 2025, Unit 4, Q8(c)(iv) (1 mark): In the body an enzyme converts L-dopa into dopamine by a decarboxylation reaction. HO NH2 HO dopamine Use this information to help you complete the equation for
  5. Summer 2025, Unit 4, Q9(a)(i) (1 mark): State reagent(s) that can be used for stage 1 [1]
  6. Summer 2025, Unit 4, Q9(a)(ii) (1 mark): State the type of reaction occurring in stage 1 [1]
  7. Summer 2025, Unit 4, Q9(a)(iii) (1 mark): One way of carrying out stage 2 is to react benzoic acid with phosphorus(V) chloride. Explain why the yield of benzoyl chloride, C6H5COCl, will be lower if mois
  8. Summer 2025, Unit 4, Q9(a)(iv) (1 mark): In stage 3 benzamide is produced from benzoyl chloride by its reaction with ammonia. Suggest the structure of the compound produced if benzoyl chloride reacts w
  9. Summer 2025, Unit 4, Q9(a)(v) (1 mark): In the reaction sequence opposite, benzamide is made from benzoic acid via the acid chloride, benzoyl chloride. It can be made from benzoic acid by a different
  10. Summer 2024, Unit 4, Q7(d)(ii) (1 mark): State what is seen when compound J reacts with sodium hydrogencarbonate solution. [1]
  11. Summer 2024, Unit 4, Q9(a)(i) (1 mark): Balance the equation for the first stage of this process. [1] COOC4H9 C4H9OH + CO + O2 + H2O COOC4H9
  12. Summer 2024, Unit 4, Q9(e) (1 mark): Decarboxylation occurs when carboxylic acids are heated with sodalime. State the name of the organic compound produced when 4-ethylbenzenecarboxylic acid is hea
  13. Summer 2024, Unit 4, Q11(a)(i) (2 marks): In the first stage adipamide is hydrolysed using aqueous sodium hydroxide, giving disodium hexanedioate as one of the products. Complete and balance the equatio
  14. Summer 2023, Unit 4, Q7(a) (1 mark): Reagent F is . [1]
  15. Summer 2023, Unit 4, Q7(b) (1 mark): Give the structure of Compound G. [1]
  16. Summer 2023, Unit 4, Q8(a)(ii) (4 marks): Sorbic acid and its salts, for example sodium sorbate, have important uses as antimicrobial agents in food preservation. Some moulds are, however, able to detox
  17. Summer 2023, Unit 4, Q9(a)(i) (1 mark): State the type of reaction occurring. [1]
  18. Summer 2023, Unit 4, Q9(b)(i) (1 mark): The acid chloride, benzene-1,4-dicarbonyl dichloride, ClOC C6H4 COCI is made by reacting benzene-1,4-dicarboxylic acid with phosphorus(V) chloride. The other pr
  19. Summer 2023, Unit 4, Q9(c)(i) (1 mark): State the name of reagent(s) A. [1]
  20. Summer 2023, Unit 4, Q9(c)(ii) (1 mark): State the name of reagent(s) B. [1]
  21. Summer 2023, Unit 4, Q9(c)(iii) (1 mark): State the type of mechanism occurring in Stage 2 [1]
  22. Summer 2022, Unit 4, Q3 (1 mark): Complete the equation for the reaction shown below. [1] O Cl C + H2O + Cl
  23. Summer 2022, Unit 4, Q7(a)(i) (1 mark): Give the structure of an isomer that gives bubbles of carbon dioxide when tested with aqueous sodium hydrogencarbonate. [1]
  24. Summer 2022, Unit 4, Q9(f)(ii) (1 mark): The reaction in part (i) is carried out in the presence of aqueous sodium hydroxide, which removes HCl as it is formed. Explain why this method would not be sui
  25. Summer 2022, Unit 4, Q10(c)(i) (3 marks): When this compound is warmed with excess aqueous sodium hydroxide, only the amide group reacts. I. Give the structure of the organic product. [1] II. State the
  26. Summer 2022, Unit 4, Q12(a)(ii) (1 mark): Compound A is an ester that is made by reacting together 2-ethylhexanol and the appropriate acid, in the presence of a catalyst. Give the molecular formula of t
  27. Summer 2022, Unit 4, Q12(b)(iii) (2 marks): Oils such as palm oil can be refined and used to make soaps such as sodium oleate. Complete the equation below, which represents the alkaline hydrolysis of the
  28. Summer 2019, Unit 4, Q2 (1 mark): Alkanes are produced when carboxylic acids are strongly heated with sodalime. State the name of a carboxylic acid that will produce propane, when heated in this
  29. Summer 2019, Unit 4, Q4 (1 mark): Using the letters provided, place these three compounds in order of increasing acidity. [1] COOH (CH3)3N OH OH A B C least most acidic acidic
  30. Summer 2019, Unit 4, Q8(e) (1 mark): Hydroxyethanoic acid, CH2(OH)COOH, can also be prepared by reacting chloroethanoic acid with aqueous sodium hydroxide. Explain why the reaction mixture needs to
  31. Summer 2019, Unit 4, Q10(c)(i) (1 mark): When ethanoic acid is heated with urea, NH2CONH2, the products are ethanamide, carbon dioxide and ammonia. Give the equation for this reaction. [1]
  32. Summer 2019, Unit 4, Q10(c)(ii) (1 mark): Suggest why an amide can act as a base. [1]
  33. Summer 2019, Unit 4, Q11(b) (1 mark): 2,3-Dihydroxybenzaldehyde has the same molecular formula as 2-hydroxybenzenecarboxylic acid. O H C OH OH Suggest a simple reaction that will give a positive res
  34. Summer 2019, Unit 4, Q12(b)(i) (1 mark): A laboratory experiment to demonstrate the formation of a polyamide uses decanedioyl dichloride. Cl Cl C (CH2)8 C O O State the name of a reagent used to produc
  35. Summer 2019, Unit 4, Q12(b)(iii) (1 mark): Suggest how the decanedioyl dichloride had become contaminated with decanedioic acid. [1]
  36. Summer 2018, Unit 4, Q2 (1 mark): Decarboxylation occurs when a carboxylic acid is heated with sodalime. State the name of the carboxylic acid that will produce propane when strongly heated with
  37. Summer 2018, Unit 4, Q3 (2 marks): Ammonia is produced when an amide is heated with aqueous sodium hydroxide. O O O O C R C C R C + 2NaOH + 2NH3 +Na−O O−Na+ NH2 H2N amide T In an experiment 3.90
  38. Summer 2018, Unit 4, Q6(e)(ii) (1 mark): State the name of the reducing agent used in the second stage of the reduction. [1]
  39. Summer 2018, Unit 4, Q9(b)(i) (1 mark): Give the equation for the hydrolysis of methyl ethanoate. [1]
  40. Summer 2018, Unit 4, Q9(b)(ii) (3 marks): The hydrolysis reaction can be used in a quantitative way to find the relative molecular mass of an ester. A known mass of an ester is refluxed with a known vol
  41. Summer 2018, Unit 4, Q9(b)(iii) (2 marks): Esters of ethanoic acid with the formula CH3COOC5H11 are used to give fruity flavours to confectionery. I. The material used for this flavouring is often a mixt
  42. Summer 2018, Unit 4, Q10(c) (1 mark): Hippuric acid, so called because it is found in the urine of horses, can be made by reacting aminoethanoic acid and benzoyl chloride. C6H5 H C O NH2 N O H H C C
  43. Summer 2017, Unit 4, Q3 (1 mark): Complete the equation for the reaction of sodium 2-hydroxybenzoate with soda lime (NaOH), which, on strong heating, can give phenol as one of the products. [1]
  44. Summer 2017, Unit 4, Q6 (1 mark): Give the systematic name of a compound of formula C5H10O2 that gives propan-1-ol as one of the products when it is warmed with aqueous sodium hydroxide. [1]
  45. Summer 2017, Unit 4, Q9(a)(i) (1 mark): One method of preparing DEET is by the following reaction sequence. O O COOH C C (C2H5)2NH reagent C Cl N(C2H5)2 Identify reagent C that can be used to convert
  46. Summer 2017, Unit 4, Q9(b)(i) (1 mark): State the oxidising agent used. [1]
  47. Summer 2017, Unit 4, Q9(b)(ii) (1 mark): Explain why it is necessary to acidify the product of this oxidation. [1]
  48. Summer 2017, Unit 4, Q10(b)(iii) (1 mark): Give the displayed formula of the organic compound formed when 5-amino-2-hydroxybenzoic acid reacts with aqueous sodium hydroxide in a 1:1 molar ratio. [1]
  49. Summer 2017, Unit 4, Q13(c)(iii) (1 mark): State the name of reagent G. [1]

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