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Equilibrium constants: WJEC A‑Level Chemistry questions

Every WJEC A-Level Chemistry exam question on 3.8 Equilibrium constants, 2016–2025, with its mark scheme and examiner’s report.

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Calculations

1,204 questions

  1. Q9(c)(i)

    Summer 2025 · Unit 3

    2 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2025 Unit 3, question 9(c)(i): Suggest what information this table allows us to deduce about the energy changes during this reversible reaction. [2]

  2. Q9(c)(ii)

    Summer 2025 · Unit 3

    4 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2025 Unit 3, question 9(c)(ii): A solution containing a mixture of complex [RuL5CH3] of concentration 1.25 × 10–3 mol dm–3 and carbon monoxide of concentration 7.55 × 10–4 mol dm–3 is placed i

  3. Q10(d)(i)

    Summer 2023 · Unit 3

    1 mark3.8 Equilibrium constants
    The whole paper ↗
    Summer 2023 Unit 3, question 10(d)(i): Write an expression for the equilibrium constant Kc. [1]

  4. Q10(d)(ii)

    Summer 2023 · Unit 3

    7 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2023 Unit 3, question 10(d)(ii): A student studies the equilibrium at a higher temperature. She adds samples of 0.40 mol of H2O and 0.14 mol of Cl2O to the non-aqueous solvent giving a total vo

  5. Q9(d)(iii)

    Summer 2022 · Unit 3

    2 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2022 Unit 3, question 9(d)(iii): Write an expression for the equilibrium constant Kc for this equilibrium, giving its unit. [2] Unit

  6. Q9(d)(iv)

    Summer 2022 · Unit 3

    4 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2022 Unit 3, question 9(d)(iv): of dilute hydrochloric acid. At equilibrium the pH of the solution is 1.55 and the concentration of [Fe(H2O)5(OH)]2+ is 0.103 mol dm–3. The numerical value of K

  7. Q13(b)(i)

    Summer 2019 · Unit 3

    1 mark3.8 Equilibrium constants
    The whole paper ↗
    Summer 2019 Unit 3, question 13(b)(i): Write an expression for the equilibrium constant, Kc, for this reaction. [1]

  8. Q13(b)(ii)

    Summer 2019 · Unit 3

    2 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2019 Unit 3, question 13(b)(ii): the concentration of water in any dilute aqueous solution is 55.5 mol dm–3. [2]

  9. Q13(b)(iii)

    Summer 2019 · Unit 3

    4 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2019 Unit 3, question 13(b)(iii): A solution was prepared containing equal concentrations of Cr2O7 The concentration of each was 0.057 mol dm–3. A student predicted that a solution containing eq

  10. Q13(b)(iv)

    Summer 2019 · Unit 3

    2 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2019 Unit 3, question 13(b)(iv): The value of the equilibrium constant for this reaction increases when the mixture is warmed. State and explain what information this provides about the enthalp

  11. Q9(d)(iii)

    Summer 2018 · Unit 3

    2 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2018 Unit 3, question 9(d)(iii): Write the expression for the equilibrium constant, Kc, for this reaction giving its unit. [2] [Co(H2O)6]2+ + 4Cl– a [CoCl4]2– + 6H2O Kc = Unit

  12. Q9(d)(iv)

    Summer 2018 · Unit 3

    3 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2018 Unit 3, question 9(d)(iv): A student carries out an experiment starting with separate non-aqueous solutions of [Co(H2O)6]2+ and Cl–. When the two solutions are mixed the initial concentra

  13. Q9(b)(i)

    Summer 2017 · Unit 3

    2 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2017 Unit 3, question 9(b)(i): Give the expression for the equilibrium constant, Kc, for this equilibrium, giving its unit if any. [2] Kc = Unit =

  14. Q9(b)(ii)

    Summer 2017 · Unit 3

    5 marks3.8 Equilibrium constants
    The whole paper ↗
    Summer 2017 Unit 3, question 9(b)(ii): The equilibrium constants for the N2O4 /NO2 equilibrium measured at room temperature in some different solvents are listed below. Equilibrium constant, Kc Solve
All 14 questions on Equilibrium constants, as a list
  1. Summer 2025, Unit 3, Q9(c)(i) (2 marks): Suggest what information this table allows us to deduce about the energy changes during this reversible reaction. [2]
  2. Summer 2025, Unit 3, Q9(c)(ii) (4 marks): A solution containing a mixture of complex [RuL5CH3] of concentration 1.25 × 10–3 mol dm–3 and carbon monoxide of concentration 7.55 × 10–4 mol dm–3 is placed i
  3. Summer 2023, Unit 3, Q10(d)(i) (1 mark): Write an expression for the equilibrium constant Kc. [1]
  4. Summer 2023, Unit 3, Q10(d)(ii) (7 marks): A student studies the equilibrium at a higher temperature. She adds samples of 0.40 mol of H2O and 0.14 mol of Cl2O to the non-aqueous solvent giving a total vo
  5. Summer 2022, Unit 3, Q9(d)(iii) (2 marks): Write an expression for the equilibrium constant Kc for this equilibrium, giving its unit. [2] Unit
  6. Summer 2022, Unit 3, Q9(d)(iv) (4 marks): of dilute hydrochloric acid. At equilibrium the pH of the solution is 1.55 and the concentration of [Fe(H2O)5(OH)]2+ is 0.103 mol dm–3. The numerical value of K
  7. Summer 2019, Unit 3, Q13(b)(i) (1 mark): Write an expression for the equilibrium constant, Kc, for this reaction. [1]
  8. Summer 2019, Unit 3, Q13(b)(ii) (2 marks): the concentration of water in any dilute aqueous solution is 55.5 mol dm–3. [2]
  9. Summer 2019, Unit 3, Q13(b)(iii) (4 marks): A solution was prepared containing equal concentrations of Cr2O7 The concentration of each was 0.057 mol dm–3. A student predicted that a solution containing eq
  10. Summer 2019, Unit 3, Q13(b)(iv) (2 marks): The value of the equilibrium constant for this reaction increases when the mixture is warmed. State and explain what information this provides about the enthalp
  11. Summer 2018, Unit 3, Q9(d)(iii) (2 marks): Write the expression for the equilibrium constant, Kc, for this reaction giving its unit. [2] [Co(H2O)6]2+ + 4Cl– a [CoCl4]2– + 6H2O Kc = Unit
  12. Summer 2018, Unit 3, Q9(d)(iv) (3 marks): A student carries out an experiment starting with separate non-aqueous solutions of [Co(H2O)6]2+ and Cl–. When the two solutions are mixed the initial concentra
  13. Summer 2017, Unit 3, Q9(b)(i) (2 marks): Give the expression for the equilibrium constant, Kc, for this equilibrium, giving its unit if any. [2] Kc = Unit =
  14. Summer 2017, Unit 3, Q9(b)(ii) (5 marks): The equilibrium constants for the N2O4 /NO2 equilibrium measured at room temperature in some different solvents are listed below. Equilibrium constant, Kc Solve

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