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Organic synthesis and analysis: WJEC A‑Level Chemistry questions

Every WJEC A-Level Chemistry exam question on 4.8 Organic synthesis and analysis, 2016–2025, with its mark scheme and examiner’s report.

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1,204 questions

  1. Q1(b)

    Summer 2025 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2025 Unit 4, question 1(b): The final stage in the production of TNT is its purification. Pure TNT has a melting temperature of 80 °C. State how this melting temperature will be affected i

  2. Q5(b)(iv)

    Summer 2025 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2025 Unit 4, question 5(b)(iv): The structure of compound E suggests that it can be polymerised. I. Give the structure of the repeating section obtained when compound E produces an addition po

  3. Q7(a)

    Summer 2025 · Unit 4

    6 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2025 Unit 4, question 7(a): You are provided with a 5 g sample of sodium benzoate contaminated with a small quantity of sand. Use the information below to devise a method that others could

  4. Q7(b)(ii)

    Summer 2025 · Unit 4

    3 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2025 Unit 4, question 7(b)(ii): 9 2 2 2 δ / ppm 8 7 6 5 4 3 2 1 0 Use the molar mass from part (i) and this spectrum to deduce the structure of the alkyl group R. Give your reasoning. [3] R ha

  5. Q8(b)(i)

    Summer 2024 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 8(b)(i): Describe how you would separate these two layers. [1]

  6. Q8(b)(iii)

    Summer 2024 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 8(b)(iii): O (CH3)3C C CH3 pinacolone Complete the table below that describes these two signals. [2] Protons Splitting pattern Relative peak area CH3CO (CH3)3C

  7. Q8(b)(iv)

    Summer 2024 · Unit 4

    4 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 8(b)(iv): Under suitable conditions pinacolone was reduced, giving a mixture of 2,2-dimethylbutane and 3,3-dimethylbutan-2-ol together with some unreacted pinacolone. The

  8. Q11(a)(iv)

    Summer 2024 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 11(a)(iv): An alternative method for producing hexanedioic acid is to treat adipamide with nitric(III) acid. H2NOC(CH2)4CONH2 + 2HNO2 HOOC(CH2)4COOH + 2N2 + 2H2O I. Give o

  9. Q11(b)(iii)

    Summer 2024 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 11(b)(iii): The tripeptide is hydrolysed to give its amino acid fragments. A solution containing these three amino acids is separated using thin layer chromatography. Use t

  10. Q9(a)(iii)

    Summer 2023 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 9(a)(iii): the peak area ratio of 6:1. Use this information and the relative molecular mass of the RCOCl, obtained in part (ii), to find the structure of the acid chloride

  11. Q9(b)(ii)

    Summer 2023 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 9(b)(ii): Benzene-1,4-dicarbonyl dichloride reacts with benzene-1,4-diamine to give a polyamide. Show the repeating unit for this polyamide. [1]

  12. Q9(c)(iv)

    Summer 2023 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 9(c)(iv): Draw the skeletal formula of the 5-carbon containing dicarboxylic acid used to produce Nylon 4,5. [1]

  13. Q9(d)

    Summer 2023 · Unit 4

    3 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 9(d): The depolymerisation of polyamides and polyesters present a number of difficult problems as these polymers are very stable and only slowly decompose in the envi

  14. Q11(c)(i)

    Summer 2023 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 11(c)(i): These amino acids are colourless and the chromatogram is sprayed with a solution of ninhydrin, so that the amino acids appear as purple dots. The colour is due

  15. Q12(b)(v)

    Summer 2023 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 12(b)(v): Addition polymerisation of methyl 2-methylpropenoate gives ‘Perspex’. Give the repeating unit of this polymer. [1]

  16. Q12(b)(vi)

    Summer 2023 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 12(b)(vi): Explain why the polymerisation in part (v) is described as addition polymerisation and not condensation polymerisation. [1]

  17. Q12(c)(ii)

    Summer 2023 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 12(c)(ii): of this compound. [2] Hydrogen proton Splitting pattern a b c d

  18. Q7(b)

    Summer 2022 · Unit 4

    1 mark4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 7(b): The position of the signal(s) is not required. [1] O O 1,4-dioxane

  19. Q8(b)

    Summer 2022 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 8(b): The formula of the polyamide ‘Kevlar’ is shown below. O O H H O O H C C N N C C N Give the structures of two starting materials that can react together to produ

  20. Q8(c)(i)

    Summer 2022 · Unit 4

    2 marks4.8 Organic synthesis and analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 8(c)(i): Explain why this polymer is described as an addition polymer and not as a polyester. [2]
All 44 questions on Organic synthesis and analysis, as a list
  1. Summer 2025, Unit 4, Q1(b) (1 mark): The final stage in the production of TNT is its purification. Pure TNT has a melting temperature of 80 °C. State how this melting temperature will be affected i
  2. Summer 2025, Unit 4, Q5(b)(iv) (2 marks): The structure of compound E suggests that it can be polymerised. I. Give the structure of the repeating section obtained when compound E produces an addition po
  3. Summer 2025, Unit 4, Q7(a) (6 marks): You are provided with a 5 g sample of sodium benzoate contaminated with a small quantity of sand. Use the information below to devise a method that others could
  4. Summer 2025, Unit 4, Q7(b)(ii) (3 marks): 9 2 2 2 δ / ppm 8 7 6 5 4 3 2 1 0 Use the molar mass from part (i) and this spectrum to deduce the structure of the alkyl group R. Give your reasoning. [3] R ha
  5. Summer 2024, Unit 4, Q8(b)(i) (1 mark): Describe how you would separate these two layers. [1]
  6. Summer 2024, Unit 4, Q8(b)(iii) (2 marks): O (CH3)3C C CH3 pinacolone Complete the table below that describes these two signals. [2] Protons Splitting pattern Relative peak area CH3CO (CH3)3C
  7. Summer 2024, Unit 4, Q8(b)(iv) (4 marks): Under suitable conditions pinacolone was reduced, giving a mixture of 2,2-dimethylbutane and 3,3-dimethylbutan-2-ol together with some unreacted pinacolone. The
  8. Summer 2024, Unit 4, Q11(a)(iv) (2 marks): An alternative method for producing hexanedioic acid is to treat adipamide with nitric(III) acid. H2NOC(CH2)4CONH2 + 2HNO2 HOOC(CH2)4COOH + 2N2 + 2H2O I. Give o
  9. Summer 2024, Unit 4, Q11(b)(iii) (2 marks): The tripeptide is hydrolysed to give its amino acid fragments. A solution containing these three amino acids is separated using thin layer chromatography. Use t
  10. Summer 2023, Unit 4, Q9(a)(iii) (2 marks): the peak area ratio of 6:1. Use this information and the relative molecular mass of the RCOCl, obtained in part (ii), to find the structure of the acid chloride
  11. Summer 2023, Unit 4, Q9(b)(ii) (1 mark): Benzene-1,4-dicarbonyl dichloride reacts with benzene-1,4-diamine to give a polyamide. Show the repeating unit for this polyamide. [1]
  12. Summer 2023, Unit 4, Q9(c)(iv) (1 mark): Draw the skeletal formula of the 5-carbon containing dicarboxylic acid used to produce Nylon 4,5. [1]
  13. Summer 2023, Unit 4, Q9(d) (3 marks): The depolymerisation of polyamides and polyesters present a number of difficult problems as these polymers are very stable and only slowly decompose in the envi
  14. Summer 2023, Unit 4, Q11(c)(i) (1 mark): These amino acids are colourless and the chromatogram is sprayed with a solution of ninhydrin, so that the amino acids appear as purple dots. The colour is due
  15. Summer 2023, Unit 4, Q12(b)(v) (1 mark): Addition polymerisation of methyl 2-methylpropenoate gives ‘Perspex’. Give the repeating unit of this polymer. [1]
  16. Summer 2023, Unit 4, Q12(b)(vi) (1 mark): Explain why the polymerisation in part (v) is described as addition polymerisation and not condensation polymerisation. [1]
  17. Summer 2023, Unit 4, Q12(c)(ii) (2 marks): of this compound. [2] Hydrogen proton Splitting pattern a b c d
  18. Summer 2022, Unit 4, Q7(b) (1 mark): The position of the signal(s) is not required. [1] O O 1,4-dioxane
  19. Summer 2022, Unit 4, Q8(b) (2 marks): The formula of the polyamide ‘Kevlar’ is shown below. O O H H O O H C C N N C C N Give the structures of two starting materials that can react together to produ
  20. Summer 2022, Unit 4, Q8(c)(i) (2 marks): Explain why this polymer is described as an addition polymer and not as a polyester. [2]
  21. Summer 2022, Unit 4, Q9(a)(iii) (1 mark): Suggest and explain a practical problem that might occur at the end of stage 1, before proceeding to stage 2 [1]
  22. Summer 2022, Unit 4, Q10(a) (6 marks): Compound G contains only carbon, hydrogen and oxygen. It has a molar mass of 72 g mol–1 of which 50.0% is carbon. The compound reacts positively with Tollens’ r
  23. Summer 2022, Unit 4, Q11(a)(i) (1 mark): Using a particular solvent tyrosine has an Rf value of 0.67. On the chromatogram below show the spot given by tyrosine. [1] 10 9 solvent front 8 7 6 5 4 3 2 sta
  24. Summer 2019, Unit 4, Q3 (2 marks): Complete the table below, which describes the 1H NMR spectrum of 3 1,1,2,2,3-pentachloropropane. [2] a b Cl H H Cl C C C H Cl Cl Cl Proton(s) Splitting pattern
  25. Summer 2019, Unit 4, Q5 (1 mark): A student produced the following chromatogram of a mixture of four amino acids. The student forgot to mark the position of the solvent front. D C B A start line
  26. Summer 2019, Unit 4, Q9(b)(iii) (2 marks): The densities of biodiesel and propane-1,2,3-triol are shown in the table. These two liquids are immiscible (insoluble in each other). Density / g cm–3 Liquid b
  27. Summer 2019, Unit 4, Q12(a)(i) (1 mark): Draw a circle around an ester linkage in the repeating unit. [1]
  28. Summer 2019, Unit 4, Q12(a)(ii) (2 marks): Polyesters such as compound P can be hydrolysed by heating with aqueous sodium hydroxide. Complete the balanced equation for this hydrolysis. [2] O O C C CH2 CH
  29. Summer 2019, Unit 4, Q12(a)(iii) (1 mark): The formation of polyester P is an example of condensation polymerisation. State how this type of polymerisation differs from addition polymerisation. Refer to
  30. Summer 2019, Unit 4, Q12(a)(iv) (3 marks): One of the raw materials used to make polyester P is methylbenzene. Under suitable conditions methylbenzene can be converted to a mixture of dimethylbenzene iso
  31. Summer 2019, Unit 4, Q12(a)(v) (5 marks): The isomer of dimethylbenzene used to produce polyester P is 1,4-dimethylbenzene. In industry this isomer is oxidised by air to produce benzene-1,4-dicarboxylic
  32. Summer 2018, Unit 4, Q7(d) (5 marks): Alternative reagents can be used for this identification. One of them is hydroxylamine, NH2OH, which produces a white crystalline solid when it reacts with an a
  33. Summer 2018, Unit 4, Q8(c)(iii) (2 marks): The boiling temperatures of the organic products formed after each stage are shown below. Compound Boiling temperature / °C 1,1,1-trifluoro-2-chloroethane 7 1,1
  34. Summer 2018, Unit 4, Q9(a) (6 marks): A solid compound is believed to be the herbicide 2,4-dichlorophenoxyethanoic acid (2,4-D). Cl O O CH2 C OH Cl The following results were obtained when this comp
  35. Summer 2018, Unit 4, Q10(e)(i) (1 mark): State the name of the dicarboxylic acid that reacts with ethane-1,2-diol to give polyester E. [1]
  36. Summer 2018, Unit 4, Q10(e)(ii) (3 marks): polyester E. [3] Protons Splitting pattern Relative peak area —CH2—CH2— —CH— —CH3
  37. Summer 2017, Unit 4, Q9(c)(iii) (2 marks): The ester BA is obtained from compound T by reacting it with sodium carbonate solution. It is then removed from the mixture by extracting it with the solvent et
  38. Summer 2017, Unit 4, Q10(b)(ii) (3 marks): resolution NMR spectrum. Explain your reasoning. Reference to the position of the signals is not required. [3]
  39. Summer 2017, Unit 4, Q11(a)(ii) (2 marks): The following procedure was suggested to obtain 2-hydroxy-2-methylpropanenitrile. mix the reactants, extract the dry the keep below 15 °C reaction product ethox
  40. Summer 2017, Unit 4, Q11(a)(iv) (1 mark): The dehydration of 2-hydroxy-2-methylpropanenitrile produces 2-methylpropenenitrile, H2C=C(CH3)CN. This compound can undergo addition polymerisation giving poly
  41. Summer 2017, Unit 4, Q11(b) (2 marks): There is considerable interest in biodegradable polymers. One of these is the polyester ‘polyhydroxyvalerate’ (PHV), which is produced from starch or glucose by
  42. Summer 2017, Unit 4, Q11(c) (1 mark): State one difference between condensation polymerisation and addition polymerisation. [1]
  43. Summer 2017, Unit 4, Q12(a) (6 marks): Queen bees secrete a pheromone, compound W, which is used for a number of purposes, both inside and outside the hive. Compound W • is a straight chain aliphatic
  44. Summer 2017, Unit 4, Q13(a)(i) (4 marks): A student suggested that the compound might be one of the following. compound L BrCH2 CH CH CH2 2 compound M CH3 CH C CH2 2 Br compound N H3C CH3 C C H Br Discu

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