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Equilibrium: OCR A‑Level Chemistry B questions

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

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2,049 questions

  1. Q3(b)(i)

    June 2025 · Paper 3

    5 marksCI Equilibrium
    The whole paper ↗
    June 2025 Paper 3, question 3(b)(i): A mixture containing 3.20 mol of carbon monoxide and 2.50 mol of hydrogen is allowed to reach equilibrium in a container of volume 2.00 dm3 under the above cond

  2. Q3(b)(ii)

    June 2025 · Paper 3

    3 marksCI Equilibrium
    The whole paper ↗
    June 2025 Paper 3, question 3(b)(ii): Explain, using Equation 3.2, why the equilibrium yield of methanol increases with increasing pressure, and suggest why an even higher pressure is not used. [3]

  3. Q3(b)(iii)

    June 2025 · Paper 3

    2 marksCI Equilibrium
    The whole paper ↗
    June 2025 Paper 3, question 3(b)(iii): A copper-based catalyst is used in the reaction. Catalysts speed up reactions. Explain why catalysts only affect the rate at which equilibrium is set up and not

  4. Q33(c)(iii)

    June 2024 · Paper 1

    2 marksCI Equilibrium
    The whole paper ↗
    June 2024 Paper 1, question 33(c)(iii): Explain how increasing temperature affects the value of Kc for the reaction in Equation 33.1. [2] 26 2NO2(g) ΔH = –114 kJ mol–1 Equation 33.1 Equation 33.1 is r

  5. Q3(a)(i)

    June 2023 · Paper 2

    4 marksCI Equilibrium
    The whole paper ↗
    June 2023 Paper 2, question 3(a)(i): A student says that a low pressure is best for the industrial manufacture of hydrogen in Equation 3.1. Discuss the student’s statement. Use relevant chemistry t

  6. Q3(a)(ii)

    June 2023 · Paper 2

    4 marksCI Equilibrium
    The whole paper ↗
    June 2023 Paper 2, question 3(a)(ii): A mixture of 1.00 mol dm–3 CH4(g) and 1.00 mol dm–3 H2O(g) is allowed to reach equilibrium at 673 K in a container of volume 1.00 dm3. The equilibrium concentra

  7. Q3(a)(iii)

    June 2023 · Paper 2

    1 markCI Equilibrium
    The whole paper ↗
    June 2023 Paper 2, question 3(a)(iii): Kc for the reaction is then measured again at an increased pressure. Would the value of Kc be larger, smaller or the same? Give a reason for your answer. [1] 12

  8. Q10

    June 2022 · Paper 1

    1 markCI Equilibrium
    The whole paper ↗
    June 2022 Paper 1, question 10: Ammonia is manufactured using the process shown in Equation 10.1. A high pressure and moderate temperature are used. 2NH3(g) ∆H = –92 kJ mol–1 Equation 10.1 N2(

  9. Q34(c)

    June 2022 · Paper 1

    6 marksCI Equilibrium
    The whole paper ↗
    June 2022 Paper 1, question 34(c): Methanol is an important alcohol that can be used for making various plastics and it can also be used as a fuel. It can be produced industrially by reacting car

  10. Q33(b)(ii)

    November 2021 · Paper 1

    2 marksCI Equilibrium
    The whole paper ↗
    November 2021 Paper 1, question 33(b)(ii): The overall reaction between ammonia solution and aqueous copper ions is shown in the equation below. [Cu(H2O)6]2+(aq) + 4NH3(aq) [Cu(NH3)4(H2O)]2+(aq) + 5H2O(l

  11. Q33(b)(iii)

    November 2021 · Paper 1

    3 marksCI Equilibrium
    The whole paper ↗
    November 2021 Paper 1, question 33(b)(iii): The students mix 0.022 mol of [Cu(H2O)6]2+(aq) and 0.081 mol of ammonia in 1.0 dm3 of solution. They find that the concentration of the [Cu(NH3)4(H2O)]2+ comple

  12. Q4(c)(ii)

    November 2021 · Paper 2

    6 marksCI Equilibrium
    The whole paper ↗
    November 2021 Paper 2, question 4(c)(ii): Some students investigate the dissolving of potassium salts. (ii)* A chemical company considers the conditions for making NO by the process shown in Equation 4.

  13. Q31(e)

    November 2020 · Paper 1

    4 marksCI Equilibrium
    The whole paper ↗
    November 2020 Paper 1, question 31(e): It has been stated that cars cause the most pollution on short journeys. Evaluate this statement in terms of the rate and equilibrium position of the reaction s

  14. Q31(f)

    November 2020 · Paper 1

    4 marksCI Equilibrium
    The whole paper ↗
    November 2020 Paper 1, question 31(f): The urea used in the exhaust system is manufactured from ammonia and carbon dioxide. The production of ammonia is given by equation 31.2. N2(g) + 3H2(g) 2NH3(g)

  15. Q12

    June 2019 · Paper 1

    1 markCI Equilibrium
    The whole paper ↗
    June 2019 Paper 1, question 12: Which statement about the manufacture of methanol is correct? CH3OH(g) ΔrH = –91 kJ mol–1 CO(g) + 2H2(g) A The best yield of methanol is obtained at high temper

  16. Q31(d)(i)

    June 2019 · Paper 1

    6 marksCI Equilibrium
    The whole paper ↗
    June 2019 Paper 1, question 31(d)(i): Some of the ammonia is converted to nitric acid in the sequence of reactions shown below: 4NO(g) + 6H2O(g) ΔrH = –905 kJ mol–1 4NH3(g) + 5O2(g) Equation 31.2 2N

  17. Q36(e)

    June 2018 · Paper 1

    3 marksCI Equilibrium
    The whole paper ↗
    June 2018 Paper 1, question 36(e): The Haber process for the manufacture of ammonia is shown in equation 36.3. 2NH3(g) ΔH = –92 kJ mol–1 N2(g) + 3H2(g) Equation 36.3 At a certain temperature, a m

  18. Q33(a)

    June 2017 · Paper 1

    2 marksCI Equilibrium
    The whole paper ↗
    June 2017 Paper 1, question 33(a): The position of equilibrium can be changed by altering the conditions. Complete the table to show the effects on the yield of hydrogen and the value of the equi

  19. Q33(b)

    June 2017 · Paper 1

    3 marksCI Equilibrium
    The whole paper ↗
    June 2017 Paper 1, question 33(b): 2.00 moles of methane and 1.00 mole of steam are allowed to reach equilibrium in a 1.00 dm3 container. At equilibrium 0.66 mole of steam remains. Calculate a va
All 19 questions on Equilibrium, as a list
  1. June 2025, Paper 3, Q3(b)(i) (5 marks): A mixture containing 3.20 mol of carbon monoxide and 2.50 mol of hydrogen is allowed to reach equilibrium in a container of volume 2.00 dm3 under the above cond
  2. June 2025, Paper 3, Q3(b)(ii) (3 marks): Explain, using Equation 3.2, why the equilibrium yield of methanol increases with increasing pressure, and suggest why an even higher pressure is not used. [3]
  3. June 2025, Paper 3, Q3(b)(iii) (2 marks): A copper-based catalyst is used in the reaction. Catalysts speed up reactions. Explain why catalysts only affect the rate at which equilibrium is set up and not
  4. June 2024, Paper 1, Q33(c)(iii) (2 marks): Explain how increasing temperature affects the value of Kc for the reaction in Equation 33.1. [2] 26 2NO2(g) ΔH = –114 kJ mol–1 Equation 33.1 Equation 33.1 is r
  5. June 2023, Paper 2, Q3(a)(i) (4 marks): A student says that a low pressure is best for the industrial manufacture of hydrogen in Equation 3.1. Discuss the student’s statement. Use relevant chemistry t
  6. June 2023, Paper 2, Q3(a)(ii) (4 marks): A mixture of 1.00 mol dm–3 CH4(g) and 1.00 mol dm–3 H2O(g) is allowed to reach equilibrium at 673 K in a container of volume 1.00 dm3. The equilibrium concentra
  7. June 2023, Paper 2, Q3(a)(iii) (1 mark): Kc for the reaction is then measured again at an increased pressure. Would the value of Kc be larger, smaller or the same? Give a reason for your answer. [1] 12
  8. June 2022, Paper 1, Q10 (1 mark): Ammonia is manufactured using the process shown in Equation 10.1. A high pressure and moderate temperature are used. 2NH3(g) ∆H = –92 kJ mol–1 Equation 10.1 N2(
  9. June 2022, Paper 1, Q34(c) (6 marks): Methanol is an important alcohol that can be used for making various plastics and it can also be used as a fuel. It can be produced industrially by reacting car
  10. November 2021, Paper 1, Q33(b)(ii) (2 marks): The overall reaction between ammonia solution and aqueous copper ions is shown in the equation below. [Cu(H2O)6]2+(aq) + 4NH3(aq) [Cu(NH3)4(H2O)]2+(aq) + 5H2O(l
  11. November 2021, Paper 1, Q33(b)(iii) (3 marks): The students mix 0.022 mol of [Cu(H2O)6]2+(aq) and 0.081 mol of ammonia in 1.0 dm3 of solution. They find that the concentration of the [Cu(NH3)4(H2O)]2+ comple
  12. November 2021, Paper 2, Q4(c)(ii) (6 marks): Some students investigate the dissolving of potassium salts. (ii)* A chemical company considers the conditions for making NO by the process shown in Equation 4.
  13. November 2020, Paper 1, Q31(e) (4 marks): It has been stated that cars cause the most pollution on short journeys. Evaluate this statement in terms of the rate and equilibrium position of the reaction s
  14. November 2020, Paper 1, Q31(f) (4 marks): The urea used in the exhaust system is manufactured from ammonia and carbon dioxide. The production of ammonia is given by equation 31.2. N2(g) + 3H2(g) 2NH3(g)
  15. June 2019, Paper 1, Q12 (1 mark): Which statement about the manufacture of methanol is correct? CH3OH(g) ΔrH = –91 kJ mol–1 CO(g) + 2H2(g) A The best yield of methanol is obtained at high temper
  16. June 2019, Paper 1, Q31(d)(i) (6 marks): Some of the ammonia is converted to nitric acid in the sequence of reactions shown below: 4NO(g) + 6H2O(g) ΔrH = –905 kJ mol–1 4NH3(g) + 5O2(g) Equation 31.2 2N
  17. June 2018, Paper 1, Q36(e) (3 marks): The Haber process for the manufacture of ammonia is shown in equation 36.3. 2NH3(g) ΔH = –92 kJ mol–1 N2(g) + 3H2(g) Equation 36.3 At a certain temperature, a m
  18. June 2017, Paper 1, Q33(a) (2 marks): The position of equilibrium can be changed by altering the conditions. Complete the table to show the effects on the yield of hydrogen and the value of the equi
  19. June 2017, Paper 1, Q33(b) (3 marks): 2.00 moles of methane and 1.00 mole of steam are allowed to reach equilibrium in a 1.00 dm3 container. At equilibrium 0.66 mole of steam remains. Calculate a va

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