Lesson 3.1.6.2

3.1.6.2 Equilibrium constant Kc for homogeneous systems Quiz: AQA Chemistry, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.6.2, Equilibrium constant Kc for homogeneous systems: 20 multiple choice questions for the AQA Chemistry (7405), Unit 1: Physical chemistry, written with Revision Ninja.

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The 20 questions

  1. Which expression is the correct Kc for the homogeneous equilibrium 2A(g) + B(g) <=> C(g)?

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

  2. Which expression is the correct Kc for the equilibrium N2O4(g) <=> 2NO2(g)?

    • Kc = [NO2]/[N2O4]
    • Kc = [N2O4]/[NO2]^2
    • Kc = [NO2]^2/[N2O4]
    • Kc = [NO2]^2 [N2O4]

  3. At equilibrium for H2(g) + I2(g) <=> 2HI(g), [H2] = 0.10, [I2] = 0.10 and [HI] = 0.80 mol dm^-3. What is Kc?

    • 16
    • 0.016
    • 64
    • 8

  4. For 2SO2(g) + O2(g) <=> 2SO3(g), at equilibrium [SO2] = 0.20, [O2] = 0.10 and [SO3] = 0.50 mol dm^-3. What is Kc?

    • 62.5 dm^3 mol^-1
    • 250 dm^3 mol^-1
    • 0.4 dm^3 mol^-1
    • 2.5 dm^3 mol^-1

  5. For A + B <=> C + D, the equilibrium concentrations are [A] = 0.50, [B] = 0.20, [C] = 0.40 and [D] = 0.10 mol dm^-3. What is Kc?

    • 2.5
    • 0.4
    • 4.0
    • 0.04

  6. The equilibrium PCl5(g) <=> PCl3(g) + Cl2(g) has [PCl5] = 0.20, [PCl3] = 0.40 and [Cl2] = 0.40 mol dm^-3. What is Kc?

    • 0.8 mol dm^-3
    • 1.6 mol dm^-3
    • 0.4 mol dm^-3
    • 0.2 mol dm^-3

  7. In an equilibrium 2HI <=> H2 + I2 in a 2 dm^3 vessel, the amounts at equilibrium are 0.4 mol HI, 0.1 mol H2 and 0.1 mol I2. What is Kc?

    • 0.0625
    • 0.0156
    • 0.0313
    • 0.2500

  8. What are the units of Kc for the equilibrium N2(g) + 3H2(g) ⇌ 2NH3(g)?

    • mol² dm⁻⁶
    • mol⁻¹ dm³
    • mol⁻² dm⁶
    • mol dm⁻³

  9. What are the units of Kc for the homogeneous equilibrium A(g) + B(g) ⇌ 2C(g)?

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

  10. Which factor alters the numerical value of the equilibrium constant Kc for a reaction?

    • Temperature
    • Concentration
    • Catalyst
    • Pressure

  11. What happens to the value of Kc for an exothermic reaction when temperature is increased?

    • Remains unchanged
    • Decreases
    • Doubles
    • Increases

  12. What happens to the value of Kc when reactant concentration is increased at constant temperature?

    • Increases
    • Remains unchanged
    • Becomes zero
    • Decreases

  13. If a temperature change shifts an equilibrium position to the right, what happens to Kc?

    • Increases
    • Becomes zero
    • Decreases
    • Remains unchanged

  14. How does adding a catalyst affect the numerical value of the equilibrium constant Kc?

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

  15. What determines the powers used in the expression for the equilibrium constant Kc?

    • Activation energies
    • Temperature changes
    • Stoichiometric coefficients
    • Reactant concentrations

  16. For the equilibrium 2A(g) + B(g) <=> 2C(g) + D(g), which is the correct expression for Kc?

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

  17. In esterification with Kc = 4, what is the new Kc if initial reactant moles double at constant temperature?

    • 2
    • 4
    • 8
    • 16

  18. For N2O4(g) <=> 2NO2(g), a vessel has [N2O4] = 0.040 and [NO2] = 0.040 mol dm^-3 at equilibrium. What is Kc?

    • 25 mol dm^-3
    • 0.0016 mol dm^-3
    • 1.0 mol dm^-3
    • 0.040 mol dm^-3

  19. A mixture contains 0.30 mol of A and 0.30 mol of B in 1.0 dm^3 and reaches equilibrium with 0.10 mol of C for A + B <=> C. What is Kc?

    • 0.10 dm^3 mol^-1
    • 0.033 dm^3 mol^-1
    • 2.5 dm^3 mol^-1
    • 10 dm^3 mol^-1

  20. For N2O4(g) <=> 2NO2(g), Kc = 0.50 mol dm^-3 at a fixed temperature. If [N2O4] = 0.20 mol dm^-3 at equilibrium, what is [NO2]?

    • 0.32 mol dm^-3
    • 2.5 mol dm^-3
    • 0.40 mol dm^-3
    • 0.10 mol dm^-3

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