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Equilibrium II: Edexcel A‑Level Chemistry questions

Every Edexcel A-Level Chemistry exam question on 11 Equilibrium II, 2016–2025, with its mark scheme and examiner’s report.

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2,028 questions

  1. Q4(a)

    June 2025 · Paper 1

    5 marks11 Equilibrium II
    The whole paper ↗
    June 2025 Paper 1, question 4(a): Calculate the value of Kp at this temperature. Include the expression for Kp and units as appropriate. (5)

  2. Q4(b)(ii)

    June 2025 · Paper 1

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2025 Paper 1, question 4(b)(ii): Which of these factors would change the value of Kp? (1) A using a different catalyst B increasing the pressure C decreasing the temperature D increasing the vo

  3. Q7(a)(i)

    June 2024 · Paper 1

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2024 Paper 1, question 7(a)(i): What are the expression and the units for the equilibrium constant (Kp) for this reaction? (1) Expression Units p SO 3 atm2 A ½ p SO p O 2 2 ½ p SO p O 2 2 atm½

  4. Q7(a)(ii)

    June 2024 · Paper 1

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2024 Paper 1, question 7(a)(ii): Which variable affects the value of Kp ? (1) A pressure B temperature C surface area of the catalyst D concentration of O2(g)

  5. Q3(c)(iii)

    June 2023 · Paper 1

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2023 Paper 1, question 3(c)(iii): The equilibrium position for the dissociation of molten I2Cl6 lies to the left. I2Cl6  ICl2 + + ICl4 – What is the most likely numerical value of Kc for this e

  6. Q10(b)(iii)

    June 2023 · Paper 3

    6 marks11 Equilibrium II
    The whole paper ↗
    June 2023 Paper 3, question 10(b)(iii): 50.0 mol of carbon monoxide is mixed with excess impure solid nickel at 323 K in an industrial reactor. At equilibrium, 0.750 mol of carbon monoxide remains. Th

  7. Q8(d)

    June 2022 · Paper 1

    7 marks11 Equilibrium II
    The whole paper ↗
    June 2022 Paper 1, question 8(d): When solid lead(II) sulfate is added to aqueous sodium iodide, an equilibrium is established. –(aq)  PbI2(s) + SO4 2–(aq) PbSO4(s) + 2I The expression for the

  8. Q9(b)

    November 2021 · Paper 3

    4 marks11 Equilibrium II
    The whole paper ↗
    November 2021 Paper 3, question 9(b): The equilibrium constants for Kp and Kc are related by the equation K Kp = c )∆ ( RT n where ∆n is the number of moles of reactants minus the number of moles of

  9. Q9(c)

    November 2021 · Paper 3

    5 marks11 Equilibrium II
    The whole paper ↗
    November 2021 Paper 3, question 9(c): A mixture of 1.0 mol of nitrogen and 3.0 mol of hydrogen is left to reach equilibrium at 700 K. Calculate the total pressure, in atmospheres, needed to produce

  10. Q9(d)

    November 2021 · Paper 3

    4 marks11 Equilibrium II
    The whole paper ↗
    November 2021 Paper 3, question 9(d): The value of the equilibrium constant, Kp, varies with temperature. The equation relating the values of the equilibrium constant at two temperatures is H In K 

  11. Q7(a)(ii)

    October 2020 · Paper 1

    3 marks11 Equilibrium II
    The whole paper ↗
    October 2020 Paper 1, question 7(a)(ii): The initial amounts of ethanol and ethanoic acid used were 1.2 mol of each reactant. Use this information, your expression for the equilibrium constant, Kc , an

  12. Q7(b)(ii)

    October 2020 · Paper 1

    1 mark11 Equilibrium II
    The whole paper ↗
    October 2020 Paper 1, question 7(b)(ii): The reaction often forms an equilibrium mixture. Which could be the units for the equilibrium constant, Kp? (1) A mol dm−3 B dm3 mol−1 C atm D atm−1

  13. Q7(b)(iii)

    October 2020 · Paper 1

    2 marks11 Equilibrium II
    The whole paper ↗
    October 2020 Paper 1, question 7(b)(iii): Describe what effect, if any, increasing the pressure would have on the equilibrium constant, Kp. Justify your answer. (2)

  14. Q10(a)(i)

    June 2019 · Paper 1

    5 marks11 Equilibrium II
    The whole paper ↗
    June 2019 Paper 1, question 10(a)(i): Calculate the value of Kp at this temperature. Include units, if appropriate. (5)

  15. Q10(a)(iii)

    June 2019 · Paper 1

    2 marks11 Equilibrium II
    The whole paper ↗
    June 2019 Paper 1, question 10(a)(iii): Deduce, by referring to Kp , how the number of sulfur dioxide molecules will change if more oxygen is added to the equilibrium mixture. (2)

  16. Q6(b)(ii)

    June 2018 · Paper 1

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2018 Paper 1, question 6(b)(ii): Give the units for Kc . (1)

  17. Q8(a)

    June 2018 · Paper 3

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2018 Paper 3, question 8(a): State the role of the hydrochloric acid in the esterification reaction. (1)

  18. Q8(b)(i)

    June 2018 · Paper 3

    2 marks11 Equilibrium II
    The whole paper ↗
    June 2018 Paper 3, question 8(b)(i): Calculate the total amount, in moles, of acid present in the volumetric flask in the equilibrium mixture. (2)

  19. Q8(b)(ii)

    June 2018 · Paper 3

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2018 Paper 3, question 8(b)(ii): The 2.0 cm3 of dilute hydrochloric acid contained 0.00400 mol of H+(aq) ions. Use this and your answer to part (b)(i) to calculate the amount, in moles, of etha

  20. Q8(c)(i)

    June 2018 · Paper 3

    1 mark11 Equilibrium II
    The whole paper ↗
    June 2018 Paper 3, question 8(c)(i): The initial mixture in the boiling tube contained 0.105 mol of ethanoic acid. Use your answer to (b)(ii) to calculate the amount, in moles, of ethanoic acid tha
All 40 questions on Equilibrium II, as a list
  1. June 2025, Paper 1, Q4(a) (5 marks): Calculate the value of Kp at this temperature. Include the expression for Kp and units as appropriate. (5)
  2. June 2025, Paper 1, Q4(b)(ii) (1 mark): Which of these factors would change the value of Kp? (1) A using a different catalyst B increasing the pressure C decreasing the temperature D increasing the vo
  3. June 2024, Paper 1, Q7(a)(i) (1 mark): What are the expression and the units for the equilibrium constant (Kp) for this reaction? (1) Expression Units p SO 3 atm2 A ½ p SO p O 2 2 ½ p SO p O 2 2 atm½
  4. June 2024, Paper 1, Q7(a)(ii) (1 mark): Which variable affects the value of Kp ? (1) A pressure B temperature C surface area of the catalyst D concentration of O2(g)
  5. June 2023, Paper 1, Q3(c)(iii) (1 mark): The equilibrium position for the dissociation of molten I2Cl6 lies to the left. I2Cl6  ICl2 + + ICl4 – What is the most likely numerical value of Kc for this e
  6. June 2023, Paper 3, Q10(b)(iii) (6 marks): 50.0 mol of carbon monoxide is mixed with excess impure solid nickel at 323 K in an industrial reactor. At equilibrium, 0.750 mol of carbon monoxide remains. Th
  7. June 2022, Paper 1, Q8(d) (7 marks): When solid lead(II) sulfate is added to aqueous sodium iodide, an equilibrium is established. –(aq)  PbI2(s) + SO4 2–(aq) PbSO4(s) + 2I The expression for the
  8. November 2021, Paper 3, Q9(b) (4 marks): The equilibrium constants for Kp and Kc are related by the equation K Kp = c )∆ ( RT n where ∆n is the number of moles of reactants minus the number of moles of
  9. November 2021, Paper 3, Q9(c) (5 marks): A mixture of 1.0 mol of nitrogen and 3.0 mol of hydrogen is left to reach equilibrium at 700 K. Calculate the total pressure, in atmospheres, needed to produce
  10. November 2021, Paper 3, Q9(d) (4 marks): The value of the equilibrium constant, Kp, varies with temperature. The equation relating the values of the equilibrium constant at two temperatures is H In K 
  11. October 2020, Paper 1, Q7(a)(ii) (3 marks): The initial amounts of ethanol and ethanoic acid used were 1.2 mol of each reactant. Use this information, your expression for the equilibrium constant, Kc , an
  12. October 2020, Paper 1, Q7(b)(ii) (1 mark): The reaction often forms an equilibrium mixture. Which could be the units for the equilibrium constant, Kp? (1) A mol dm−3 B dm3 mol−1 C atm D atm−1
  13. October 2020, Paper 1, Q7(b)(iii) (2 marks): Describe what effect, if any, increasing the pressure would have on the equilibrium constant, Kp. Justify your answer. (2)
  14. June 2019, Paper 1, Q10(a)(i) (5 marks): Calculate the value of Kp at this temperature. Include units, if appropriate. (5)
  15. June 2019, Paper 1, Q10(a)(iii) (2 marks): Deduce, by referring to Kp , how the number of sulfur dioxide molecules will change if more oxygen is added to the equilibrium mixture. (2)
  16. June 2018, Paper 1, Q6(b)(ii) (1 mark): Give the units for Kc . (1)
  17. June 2018, Paper 3, Q8(a) (1 mark): State the role of the hydrochloric acid in the esterification reaction. (1)
  18. June 2018, Paper 3, Q8(b)(i) (2 marks): Calculate the total amount, in moles, of acid present in the volumetric flask in the equilibrium mixture. (2)
  19. June 2018, Paper 3, Q8(b)(ii) (1 mark): The 2.0 cm3 of dilute hydrochloric acid contained 0.00400 mol of H+(aq) ions. Use this and your answer to part (b)(i) to calculate the amount, in moles, of etha
  20. June 2018, Paper 3, Q8(c)(i) (1 mark): The initial mixture in the boiling tube contained 0.105 mol of ethanoic acid. Use your answer to (b)(ii) to calculate the amount, in moles, of ethanoic acid tha
  21. June 2018, Paper 3, Q8(c)(ii) (3 marks): Use information given in the method, and your answer to (c)(i), to calculate the amounts, in moles, of propan-1-ol, propyl ethanoate and water that are present
  22. June 2018, Paper 3, Q8(d)(i) (1 mark): Write the expression for the equilibrium constant, Kc , for this reaction. CH3COOH(l) + CH3CH2CH2OH(l)  CH3COOCH2CH2CH3(l) + H2O(l) (1)
  23. June 2018, Paper 3, Q8(d)(ii) (2 marks): Explain why it is possible, in this case, to calculate Kc using equilibrium amounts in moles, rather than equilibrium concentrations. (2)
  24. June 2018, Paper 3, Q8(d)(iii) (2 marks): Calculate the value of Kc. Give your answer to an appropriate number of significant figures. (2)
  25. June 2018, Paper 3, Q8(e) (2 marks): The pink colour of the phenolphthalein fades after the end-point of the titration has been reached. Give a possible explanation for this observation. (2)
  26. June 2018, Paper 3, Q8(f) (2 marks): Explain what you could do to confirm that one week is sufficient time for the mixture to reach equilibrium. (2)
  27. June 2018, Paper 3, Q8(g) (2 marks): A student repeated the experiment, but left the mixture in a water bath at 40 °C until equilibrium was reached. CH3COOH(l) + CH3CH2CH2OH(l)  CH3COOCH2CH2CH3(l)
  28. June 2017, Paper 1, Q10(a)(i) (1 mark): Give a reason why the partial pressure of carbon is not included in the expression. (1)
  29. June 2017, Paper 1, Q10(a)(iii) (2 marks): Explain, by reference to any change in the value of Kp , the effect of an increase in temperature on the equilibrium position of this reaction. (2)
  30. June 2017, Paper 1, Q10(a)(iv) (4 marks): At 1000 K and a total pressure of 2.0 atm, 1.00 mol of steam reacted with excess carbon. At equilibrium, 0.81 mol of hydrogen was present. Calculate the value o
  31. June 2017, Paper 1, Q10(b) (3 marks): Carbon monoxide reacts with steam. CO(g) + H2O(g) U CO2(g) + H2(g) At 1100 K, Kc = 1.00 In an experiment, 1 mol of carbon monoxide was mixed with 1 mol of steam
  32. June 2017, Paper 3, Q9(a)(ii) (2 marks): If the starting concentration of both hydrogen and iodine was a mol dm−3 and it was found that 2y mol dm−3 of hydrogen iodide had formed once equilibrium had be
  33. June 2017, Paper 3, Q9(b)(i) (1 mark): Complete the table to give the two remaining values of y mol dm−3, to two decimal places. (1) a / mol dm−3 [I2]eq / mol dm−3 y / mol dm−3 0.20 0.02 0.18 0.80 0.
  34. June 2017, Paper 3, Q9(b)(ii) (2 marks): Plot a graph to show how y mol dm−3 varies with the initial concentrations of hydrogen and iodine, a mol dm−3. (2) 4.0 3.0 y / mol dm–3 2.0 1.0 0 0 1.0 2.0 3.0
  35. June 2017, Paper 3, Q9(b)(iii) (2 marks): Determine the gradient of your graph. Show your working on the graph. (2)
  36. June 2017, Paper 3, Q9(b)(iv) (2 marks): Use your answer to (b)(iii) and the expression y = to calculate the  2 + K value of Kc. c (2)
  37. June 2017, Paper 3, Q9(c) (1 mark): Identify a safety issue associated with this experiment. (1)
  38. June 2017, Paper 3, Q9(d) (2 marks): One of the experiments in part (b) was repeated using the same molar quantities of hydrogen and iodine but in a 500 cm3 flask instead of the 1 dm3 flask. Deduce
  39. June 2017, Paper 3, Q9(e)(i) (2 marks): Explain the effect, if any, on the value of Kc when the temperature is increased. (2)
  40. June 2017, Paper 3, Q9(e)(ii) (1 mark): On your graph in (b)(ii), draw and label the line you would expect if the experiment was carried out at 1000 K instead of 760 K. (1)

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