Lesson 10.1.1

10.1.1 Dynamic equilibrium and the equilibrium constant Kc Quiz: Pearson Edexcel Chemistry, Unit 10

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 10.1.1, Dynamic equilibrium and the equilibrium constant Kc: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 10: Equilibrium I, written with Revision Ninja.

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The 20 questions

  1. What happens to the rates of forward and reverse reactions at dynamic equilibrium?

    • Forward is faster
    • Reverse is faster
    • Both are zero
    • They are equal

  2. What happens to reactant and product concentrations at dynamic equilibrium?

    • Decrease to zero
    • Remain constant
    • Become equal
    • Increase continuously

  3. For the equilibrium N2(g) + 3H2(g) ⇌ 2NH3(g), which expression is correct for Kc?

    • Kc = [NH3]^2 / ([N2][H2]^3)
    • Kc = [NH3] / ([N2] + [H2]^3)
    • Kc = [NH3]^2 / ([N2][H2])
    • Kc = [N2][H2]^3 / [NH3]^2

  4. What are the units of Kc for the equilibrium H2(g) + I2(g) ⇌ 2HI(g)?

    • mol dm⁻³
    • dm³ mol⁻¹
    • No units
    • mol² dm⁻⁶

  5. For the equilibrium N2O4(g) ⇌ 2NO2(g), the equilibrium concentrations are [N2O4] = 0.040 mol dm-3 and [NO2] = 0.12 mol dm-3. What is Kc?

    • 0.36 mol dm-3
    • 3.0 mol dm-3
    • 0.0144 mol dm-3
    • 0.0048 mol dm-3

  6. How are pure solids included in the equilibrium constant Kc expression?

    • Included as concentrations
    • Omitted from expression
    • Multiplied by volume
    • Subtracted from products

  7. For the equilibrium CaCO3(s) ⇌ CaO(s) + CO2(g), which expression is correct for Kc?

    • Kc = [CaCO3] / [CO2]
    • Kc = [CaO] / [CaCO3]
    • Kc = [CO2]
    • Kc = [CaO][CO2] / [CaCO3]

  8. In the equilibrium 2SO2(g) + O2(g) ⇌ 2SO3(g), what is the expression for Kc?

    • Kc = [SO3]^2 / ([SO2] + [O2])
    • Kc = [SO3] / ([SO2][O2])
    • Kc = [SO3]^2 / ([SO2]^2 [O2])
    • Kc = [SO2]^2[O2] / [SO3]^2

  9. What effect does adding a catalyst have on the value of Kc?

    • Increases Kc
    • Decreases Kc
    • Doubles Kc
    • No effect

  10. What does a large value of Kc indicate about an equilibrium mixture?

    • Reaction stopped
    • Equal concentrations
    • Favours reactants
    • Favours products

  11. A reaction reaches equilibrium with [A] = 0.20 mol dm-3, [B] = 0.10 mol dm-3 and [C] = 0.50 mol dm-3, for A + B ⇌ C. What is Kc?

    • 0.04 mol-1 dm3
    • 0.4 mol-1 dm3
    • 2.5 mol-1 dm3
    • 25 mol-1 dm3

  12. For the equilibrium PCl5(g) ⇌ PCl3(g) + Cl2(g), at equilibrium [PCl5] = 0.020 mol dm-3, [PCl3] = 0.080 mol dm-3 and [Cl2] = 0.080 mol dm-3. What is Kc?

    • 0.0080 mol dm-3
    • 3.13 mol dm-3
    • 0.00200 mol dm-3
    • 0.32 mol dm-3

  13. As a system approaches dynamic equilibrium from pure reactants, what happens to the reverse rate?

    • Stays zero
    • Decreases
    • Remains constant
    • Increases

  14. What is the only factor that changes the value of Kc for a given equilibrium?

    • Pressure
    • Concentration
    • Catalyst
    • Temperature

  15. Which expression is correct for the reaction 2NO(g) + O2(g) ⇌ 2NO2(g)?

    • Kc = [NO2]^2 / ([NO]^2 [O2])
    • Kc = [NO2]^2 / ([NO] + [O2])
    • Kc = [NO2] / ([NO][O2])
    • Kc = [NO]^2 [O2] / [NO2]^2

  16. A reaction has Kc = 4.0 mol-1 dm3 for A + B ⇌ C. If [A] = 0.50 and [B] = 0.50 mol dm-3, what is [C] at equilibrium?

    • 2.0 mol dm-3
    • 0.25 mol dm-3
    • 4.0 mol dm-3
    • 1.0 mol dm-3

  17. Which feature characterises a heterogeneous dynamic equilibrium mixture?

    • Liquid phase only
    • Same physical state
    • Different physical states
    • Gas phase only

  18. Which factor alters the value of the equilibrium constant, Kc, for a given reaction?

    • Catalyst
    • Concentration
    • Temperature
    • Pressure

  19. For the equilibrium 2A + B ⇌ 3C, which expression is correct for Kc?

    • Kc = [C]^3 / ([A]^2 [B])
    • Kc = [C] / ([A][B])
    • Kc = [C]^3 / ([A] + [B])
    • Kc = [A]^2 [B] / [C]^3

  20. What is the correct Kc expression for Fe3+(aq) + SCN-(aq) ⇌ FeSCN2+(aq)?

    • [FeSCN2+] / ([Fe3+] + [SCN-])
    • [Fe3+][SCN-] / [FeSCN2+]
    • [FeSCN2+] / ([Fe3+][SCN-])
    • ([Fe3+][SCN-]) / [FeSCN2+]

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