Lesson 3.1.10

3.1.10 Equilibrium constant Kp for homogeneous systems (A-level Quiz: AQA Chemistry, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.10, Equilibrium constant Kp for homogeneous systems (A-level: 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. How is the partial pressure of a gas in a mixture calculated?

    • Mole fraction x total pressure
    • Mole fraction / total pressure
    • Total pressure / mole fraction
    • Moles x total volume

  2. What is the mole fraction of gas A if 2 moles of A are present in 8 total moles?

    • 0.20
    • 0.25
    • 4.00
    • 0.16

  3. For 2SO2(g) + O2(g) <=> 2SO3(g), which is the correct expression for Kp?

    • Kp = p(SO3) / (p(SO2) x p(O2))
    • Kp = p(SO3)^2 / (p(SO2)^2 x p(O2))
    • Kp = p(SO2)^2 x p(O2) / p(SO3)^2
    • Kp = p(SO3)^2 x p(SO2)^2 / p(O2)

  4. In a gas mixture with total pressure 200 kPa, the mole fraction of NH3 is 0.25. What is the partial pressure of NH3?

    • 800 kPa
    • 50 kPa
    • 0.25 kPa
    • 200 kPa

  5. At equilibrium for PCl5(g) <=> PCl3(g) + Cl2(g), the partial pressures are p(PCl5) = 0.50, p(PCl3) = 0.20 and p(Cl2) = 0.20 atm. What is Kp?

    • 0.08 atm
    • 0.40 atm
    • 1.2 atm
    • 2.5 atm^-1

  6. A mixture at a total pressure of 100 kPa contains 1 mol H2, 1 mol I2 and 2 mol HI at equilibrium for H2 + I2 <=> 2HI. What is Kp?

    • 4
    • 0.25
    • 2
    • 8

  7. For N2O4(g) <=> 2NO2(g), what is the value of Kp when p(N2O4) = 0.80 atm and p(NO2) = 0.40 atm?

    • 0.50 atm
    • 5.0 atm
    • 0.20 atm
    • 2.0 atm

  8. What are the units of Kp for N2(g) + 3H2(g) ⇌ 2NH3(g) when pressure is in kPa?

    • kPa
    • kPa^-1
    • kPa^-2
    • kPa^2

  9. What are the units of Kp for H2(g) + I2(g) ⇌ 2HI(g)?

    • kPa
    • No units
    • kPa^-1
    • kPa^2

  10. Which expression is the correct Kp for 2A(g) + B(g) <=> C(g)?

    • Kp = p(A)^2 x p(B) / p(C)
    • Kp = p(C)^2 / (p(A) x p(B))
    • Kp = p(A) x p(B) / p(C)
    • Kp = p(C) / (p(A)^2 x p(B))

  11. How does increasing temperature affect Kp for an exothermic forward reaction?

    • Kp becomes zero
    • Kp decreases
    • Kp remains unchanged
    • Kp increases

  12. Which factor alone changes the value of the equilibrium constant Kp?

    • Catalyst
    • Concentration
    • Temperature
    • Total pressure

  13. What effect does adding a catalyst have on the value of Kp?

    • Kp decreases
    • No effect
    • Kp increases
    • Kp doubles

  14. At constant temperature, what happens to Kp if total pressure is doubled?

    • Halves
    • Quadruples
    • Doubles
    • Remains unchanged

  15. At 1 atm total pressure, 0.5 mol of N2O4 dissociates for N2O4 <=> 2NO2 from 1 mol start, reaching a total pressure of 2.0 atm. What is Kp?

    • 0.67 atm
    • 2.67 atm
    • 5.33 atm
    • 1.33 atm

  16. How does adding an inert gas at constant volume affect Kp?

    • Decreases
    • Becomes zero
    • Increases
    • Remains unchanged

  17. A gas mixture has a total pressure of 150 kPa and contains 0.60 mol of gas X out of 1.20 mol in total. What is the partial pressure of X?

    • 150 kPa
    • 75 kPa
    • 30 kPa
    • 0.5 kPa

  18. For N2(g) + 3H2(g) <=> 2NH3(g), which is the correct expression for Kp?

    • Kp = p(NH3) / (p(N2) x p(H2)^3)
    • Kp = p(NH3)^2 / (p(N2) x p(H2)^3)
    • Kp = p(N2) x p(H2)^3 / p(NH3)^2
    • Kp = p(NH3)^2 / (p(N2) x p(H2))

  19. What happens to Kp for an endothermic reaction when temperature increases?

    • Remains unchanged
    • Becomes zero
    • Increases
    • Decreases

  20. Which quantity is used for each gaseous reactant in the Kp expression?

    • Total pressure
    • Partial pressure
    • Mole fraction
    • Concentration

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