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Reaction mechanisms: OCR A‑Level Chemistry B questions

Every OCR A-Level Chemistry B exam question on WM Reaction mechanisms (specification points WM(h)), 2016–2025, with its mark scheme and examiner’s report.

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2,049 questions

  1. Q32(c)(ii)

    June 2025 · Paper 1

    1 markWM Reaction mechanisms
    The whole paper ↗
    June 2025 Paper 1, question 32(c)(ii): State the type of reaction that occurs during the dehydration of an alcohol. [1]

  2. Q4

    June 2025 · AS Paper 1

    1 markWM Reaction mechanisms
    The whole paper ↗
    June 2025 AS Paper 1, question 4: Ethanol can be dehydrated. C2H5OH C2H4 + H2O What process describes this reaction? A drying B elimination C oxidation D reduction Your answer [1]

  3. Q6

    June 2023 · AS Paper 1

    1 markWM Reaction mechanisms
    The whole paper ↗
    June 2023 AS Paper 1, question 6: Which of the following is an elimination reaction? A CH3COOCH3 + NaOH CH3COONa + CH3OH B C2H4 + Br2 C2H4Br2 C C6H5OH + (CH3CO)2O C6H5OCOCH3 + CH3COOH D C2H5OH C

  4. Q3(d)(iv)

    June 2023 · AS Paper 2

    3 marksWM Organic reactionsWM Reaction mechanisms
    The whole paper ↗
    June 2023 AS Paper 2, question 3(d)(iv): C6H5CH2CH2OH undergoes a dehydration reaction when heated with concentrated sulfuric acid. However, phenylmethanol, C6H5CH2OH, does not undergo this reaction. •

  5. Q3(b)

    June 2022 · AS Paper 2

    1 markWM Reaction mechanisms
    The whole paper ↗
    June 2022 AS Paper 2, question 3(b): Reaction 2 Compound A can be dehydrated as shown. CH2CH2OH CH = CH2 Reaction 2 What type of reaction is this dehydration? [1]

  6. Q4(e)(ii)

    November 2020 · Paper 2

    1 markWM Reaction mechanisms
    The whole paper ↗
    November 2020 Paper 2, question 4(e)(ii): Name the type of reaction that is occurring in step 2. [1]

  7. Q13

    June 2017 · AS Paper 1

    1 markWM Reaction mechanisms
    The whole paper ↗
    June 2017 AS Paper 1, question 13: Which of these is classified as an elimination reaction? A CH3COOH + C2H5OH CH3COOC2H5 + H2O B CuSO4•5H2O CuSO4 + 5H2O C C2H5OH C2H4 + H2O D C17H36 C10H22 + C7H
All 7 questions on Reaction mechanisms, as a list
  1. June 2025, Paper 1, Q32(c)(ii) (1 mark): State the type of reaction that occurs during the dehydration of an alcohol. [1]
  2. June 2025, AS Paper 1, Q4 (1 mark): Ethanol can be dehydrated. C2H5OH C2H4 + H2O What process describes this reaction? A drying B elimination C oxidation D reduction Your answer [1]
  3. June 2023, AS Paper 1, Q6 (1 mark): Which of the following is an elimination reaction? A CH3COOCH3 + NaOH CH3COONa + CH3OH B C2H4 + Br2 C2H4Br2 C C6H5OH + (CH3CO)2O C6H5OCOCH3 + CH3COOH D C2H5OH C
  4. June 2023, AS Paper 2, Q3(d)(iv) (3 marks): C6H5CH2CH2OH undergoes a dehydration reaction when heated with concentrated sulfuric acid. However, phenylmethanol, C6H5CH2OH, does not undergo this reaction. •
  5. June 2022, AS Paper 2, Q3(b) (1 mark): Reaction 2 Compound A can be dehydrated as shown. CH2CH2OH CH = CH2 Reaction 2 What type of reaction is this dehydration? [1]
  6. November 2020, Paper 2, Q4(e)(ii) (1 mark): Name the type of reaction that is occurring in step 2. [1]
  7. June 2017, AS Paper 1, Q13 (1 mark): Which of these is classified as an elimination reaction? A CH3COOH + C2H5OH CH3COOC2H5 + H2O B CuSO4•5H2O CuSO4 + 5H2O C C2H5OH C2H4 + H2O D C17H36 C10H22 + C7H

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