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Organic reactions: OCR A‑Level Chemistry B questions

Every OCR A-Level Chemistry B exam question on DF Organic reactions (specification points DF(n)–(o)), 2016–2025, with its mark scheme and examiner’s report.

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2,049 questions

  1. Q31(c)(i)

    June 2025 · Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    June 2025 Paper 1, question 31(c)(i): Give the skeletal formula of the product of this hydrogenation. [1]

  2. Q23(b)

    June 2025 · AS Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    June 2025 AS Paper 1, question 23(b): Write the equation for the complete combustion of C6H12. [1]

  3. Q2(a)

    June 2025 · AS Paper 2

    2 marksDF Organic reactions
    The whole paper ↗
    June 2025 AS Paper 2, question 2(a): Give the conditions required for this industrial process. [2]

  4. Q2(b)

    June 2025 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2025 AS Paper 2, question 2(b): Ethanol can also be made in the laboratory by a two-step process as shown: CH2=CH2 + H2SO4 CH3CH2OSO3H Step 1 CH3CH2OSO3H + H2O CH3CH2OH + H2SO4 Step 2 Write th

  5. Q2(c)(ii)

    June 2025 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2025 AS Paper 2, question 2(c)(ii): When the student has carried out both steps, a mixture is left. This mixture contains an alcohol. The student finds that drops of this mixture turn bromine wate

  6. Q2(e)

    June 2025 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2025 AS Paper 2, question 2(e): Cyclopentene reacts with hydrogen in the presence of a catalyst. Name a catalyst that allows this hydrogenation to occur at room temperature and pressure. [1]

  7. Q1(e)(ii)

    June 2024 · Paper 2

    2 marksDF Organic reactions
    The whole paper ↗
    June 2024 Paper 2, question 1(e)(ii): A student suggests treating oleic acid with steam and H3PO4, using high temperature and pressure. The student says that the product will be CH3(CH2)7CH(OH)CH(OH

  8. Q3(a)

    June 2024 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2024 AS Paper 2, question 3(a): Diesel fuel made from crude oil often undergoes incomplete combustion in vehicle engines. The pollutants carbon monoxide and carbon particulates are formed. C12

  9. Q32(a)

    June 2023 · Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    June 2023 Paper 1, question 32(a): Octane, C8H18, is one of the alkane hydrocarbons present in petrol. For maximum fuel efficiency, petrol should burn completely. However, some incomplete combust

  10. Q1(e)

    June 2023 · Paper 2

    4 marksEL Formulae, equations and amount of substanceDF Organic reactions
    The whole paper ↗
    June 2023 Paper 2, question 1(e): The students have another solution containing 20 g dm–3 bromine. They find that 160 cm3 of this solution reacts exactly with 0.80 g of a hydrocarbon with a mole

  11. Q5(d)(i)

    June 2023 · Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2023 Paper 2, question 5(d)(i): Acetylene (ethyne) burns in a carbide lamp to form carbon dioxide and water. Some unreacted carbon is also formed that glows and gives light. Write a possible c

  12. Q24(c)

    June 2023 · AS Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    June 2023 AS Paper 1, question 24(c): A student carries out a simple test to show that the liquid vinyl acetate is unsaturated. Give details of the test and its result. [1]

  13. Q2(g)

    June 2022 · Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2022 Paper 2, question 2(g): But-2-ene reacts with hydrogen to form butane. Name a catalyst and the corresponding conditions for this reaction. catalyst: conditions: [1]

  14. Q12

    June 2022 · AS Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    June 2022 AS Paper 1, question 12: Ethene is reacted with the reagents shown below. Which row correctly describes the products? Steam/phosphoric Hydrogen and Hydrogen acid with heat and platinum

  15. Q21(a)(iii)

    June 2022 · AS Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    June 2022 AS Paper 1, question 21(a)(iii): Give the reagent for Reaction 1. [1]

  16. Q2(a)(iv)

    June 2022 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2022 AS Paper 2, question 2(a)(iv): The gas collected is found to turn bromine water from orange/brown to colourless. What can the student deduce from this? [1]

  17. Q4(a)(i)

    June 2022 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    June 2022 AS Paper 2, question 4(a)(i): One of the hydrocarbons in petrol is octane, C8H18. Write an equation for the complete combustion of octane. [1]

  18. Q1(f)

    November 2021 · Paper 2

    5 marksDF Organic reactions
    The whole paper ↗
    November 2021 Paper 2, question 1(f): Some reactions of but-2-ene are shown in the diagram below. Complete the diagram by filling in the incomplete boxes. CH3CHBrCHBrCH3 Observation when reaction wi

  19. Q1(b)(ii)

    November 2021 · AS Paper 2

    1 markDF Organic reactions
    The whole paper ↗
    November 2021 AS Paper 2, question 1(b)(ii): A chemist dissolves a sample of poly(propene) in a suitable solvent. The chemist wants a quick and simple way to check whether the polymer contains any unreacte

  20. Q31(a)

    November 2020 · Paper 1

    1 markDF Organic reactions
    The whole paper ↗
    November 2020 Paper 1, question 31(a): Write the equation for the complete combustion of cetane. [1]
All 35 questions on Organic reactions, as a list
  1. June 2025, Paper 1, Q31(c)(i) (1 mark): Give the skeletal formula of the product of this hydrogenation. [1]
  2. June 2025, AS Paper 1, Q23(b) (1 mark): Write the equation for the complete combustion of C6H12. [1]
  3. June 2025, AS Paper 2, Q2(a) (2 marks): Give the conditions required for this industrial process. [2]
  4. June 2025, AS Paper 2, Q2(b) (1 mark): Ethanol can also be made in the laboratory by a two-step process as shown: CH2=CH2 + H2SO4 CH3CH2OSO3H Step 1 CH3CH2OSO3H + H2O CH3CH2OH + H2SO4 Step 2 Write th
  5. June 2025, AS Paper 2, Q2(c)(ii) (1 mark): When the student has carried out both steps, a mixture is left. This mixture contains an alcohol. The student finds that drops of this mixture turn bromine wate
  6. June 2025, AS Paper 2, Q2(e) (1 mark): Cyclopentene reacts with hydrogen in the presence of a catalyst. Name a catalyst that allows this hydrogenation to occur at room temperature and pressure. [1]
  7. June 2024, Paper 2, Q1(e)(ii) (2 marks): A student suggests treating oleic acid with steam and H3PO4, using high temperature and pressure. The student says that the product will be CH3(CH2)7CH(OH)CH(OH
  8. June 2024, AS Paper 2, Q3(a) (1 mark): Diesel fuel made from crude oil often undergoes incomplete combustion in vehicle engines. The pollutants carbon monoxide and carbon particulates are formed. C12
  9. June 2023, Paper 1, Q32(a) (1 mark): Octane, C8H18, is one of the alkane hydrocarbons present in petrol. For maximum fuel efficiency, petrol should burn completely. However, some incomplete combust
  10. June 2023, Paper 2, Q1(e) (4 marks): The students have another solution containing 20 g dm–3 bromine. They find that 160 cm3 of this solution reacts exactly with 0.80 g of a hydrocarbon with a mole
  11. June 2023, Paper 2, Q5(d)(i) (1 mark): Acetylene (ethyne) burns in a carbide lamp to form carbon dioxide and water. Some unreacted carbon is also formed that glows and gives light. Write a possible c
  12. June 2023, AS Paper 1, Q24(c) (1 mark): A student carries out a simple test to show that the liquid vinyl acetate is unsaturated. Give details of the test and its result. [1]
  13. June 2022, Paper 2, Q2(g) (1 mark): But-2-ene reacts with hydrogen to form butane. Name a catalyst and the corresponding conditions for this reaction. catalyst: conditions: [1]
  14. June 2022, AS Paper 1, Q12 (1 mark): Ethene is reacted with the reagents shown below. Which row correctly describes the products? Steam/phosphoric Hydrogen and Hydrogen acid with heat and platinum
  15. June 2022, AS Paper 1, Q21(a)(iii) (1 mark): Give the reagent for Reaction 1. [1]
  16. June 2022, AS Paper 2, Q2(a)(iv) (1 mark): The gas collected is found to turn bromine water from orange/brown to colourless. What can the student deduce from this? [1]
  17. June 2022, AS Paper 2, Q4(a)(i) (1 mark): One of the hydrocarbons in petrol is octane, C8H18. Write an equation for the complete combustion of octane. [1]
  18. November 2021, Paper 2, Q1(f) (5 marks): Some reactions of but-2-ene are shown in the diagram below. Complete the diagram by filling in the incomplete boxes. CH3CHBrCHBrCH3 Observation when reaction wi
  19. November 2021, AS Paper 2, Q1(b)(ii) (1 mark): A chemist dissolves a sample of poly(propene) in a suitable solvent. The chemist wants a quick and simple way to check whether the polymer contains any unreacte
  20. November 2020, Paper 1, Q31(a) (1 mark): Write the equation for the complete combustion of cetane. [1]
  21. June 2019, Paper 1, Q5 (1 mark): Which equation is correct? A C4H8 + 5O2 3CO2 + CO + 4H2O C2H5OH + 31 B 2O2 2CO2 + 3H2O C2H4 + 31 C 2O2 2CO2 + 2H2O C8H18 + 121 D 2O2 8CO2 + 9H2O Your answer [1]
  22. June 2019, Paper 1, Q35(a) (1 mark): They look at the formulae and decide that the molecules are probably unsaturated due to the low proportion of hydrogen. They test each compound with bromine wat
  23. June 2019, Paper 1, Q35(e)(i) (1 mark): Give the reagent and conditions to convert compound A into the compound shown below. HO Reagent Conditions [1]
  24. June 2019, Paper 1, Q35(f)(i) (2 marks): Complete the reaction sequence by writing on the dotted lines. [2]
  25. June 2019, Paper 2, Q5(f) (6 marks): This question refers to the Advance Notice Article ‘Clearing the air around smoke formation’ that is included as an insert in this paper. (f)* Oxygen is involve
  26. June 2019, AS Paper 1, Q5 (1 mark): Which reaction will give CH3CH2CH(OH)CH2CH3 as a product? A Reduction of CH3CH2CH2CH2CHO B Treatment of CH2=CHCH2CH2CH3 with conc sulfuric acid followed by wate
  27. June 2019, AS Paper 1, Q16 (1 mark): Which substance cannot be made in a single step from C2H4? A C2H5OH B C2H5Br C C2H6 D C2H5NH2 Your answer [1]
  28. June 2018, AS Paper 1, Q23(a)(ii) (1 mark): They test the gas by shaking it with some aqueous bromine. Describe the colour change that they would see. [1]
  29. June 2018, AS Paper 2, Q2(c) (1 mark): One disadvantage of butan-1-ol as a fuel is that it requires a higher oxygen to fuel ratio for complete combustion when compared to ethanol. Write equations to
  30. June 2017, Paper 3, Q3(c) (4 marks): Ocimenol and cinnamyl alcohol are both unsaturated molecules. Explain how you could use a solution of bromine water to show which of the molecules has the great
  31. June 2017, AS Paper 2, Q2(c)(i) (1 mark): What colour change would be observed when phenylethene reacts with aqueous bromine? [1]
  32. June 2017, AS Paper 2, Q2(e)(i) (1 mark): Give the reagent that you would use for step 1. [1] 14 CH = CH2 C*HBrCH3 CH(OH)CH3 step 1 step 2 phenylethene 1-phenyl-1-bromoethane 1-phenylethanol
  33. June 2016, AS Paper 1, Q9 (1 mark): Which reaction will not give bromoethane as a product? A Ethane with bromine in ultraviolet radiation. B Ethene with bromine at room temperature and pressure. C
  34. June 2016, AS Paper 1, Q22(c)(i) (1 mark): Give the reagents needed to make alcohol A from isobutylene. [1]
  35. June 2016, AS Paper 2, Q4(b) (1 mark): One safety precaution when carrying out this reaction is to keep the flammable ethanol away from naked flames. Write an equation for the incomplete combustion o

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