Lesson 11.1.1

11.1.1 Kp and partial pressures Quiz: Pearson Edexcel Chemistry, Unit 11

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 11.1.1, Kp and partial pressures: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 11: Equilibrium II, written with Revision Ninja.

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The 20 questions

  1. What pressure does a gas exert if it alone occupies a container at the same temperature?

    • Vapour pressure
    • Atmospheric pressure
    • Total pressure
    • Partial pressure

  2. How do you calculate the partial pressure of a gas from its mole fraction?

    • Total pressure ÷ mole fraction
    • Mole fraction + total pressure
    • Mole fraction ÷ total pressure
    • Mole fraction × total pressure

  3. For the equilibrium N2O4(g) ⇌ 2NO2(g), what is the expression for Kp?

    • Kp = p(NO2)^2 / p(N2O4)
    • Kp = p(NO2)^2 x p(N2O4)
    • Kp = p(NO2) / p(N2O4)
    • Kp = p(N2O4) / p(NO2)^2

  4. What determines the units of the equilibrium constant Kp?

    • Total pressure
    • Equation stoichiometry
    • Activation energy
    • Catalyst presence

  5. In a mixture at total pressure 2.00 atm, NO2 has mole fraction 0.50. What is the partial pressure of NO2?

    • 1.00 atm
    • 4.00 atm
    • 0.50 atm
    • 2.00 atm

  6. For the equilibrium N2O4 ⇌ 2NO2, partial pressures at equilibrium are p(N2O4) = 0.50 atm and p(NO2) = 1.00 atm. What is Kp?

    • 0.50 atm
    • 0.67 atm
    • 2.00 atm
    • 4.00 atm

  7. For the equilibrium 2SO2(g) + O2(g) ⇌ 2SO3(g), partial pressures are p(SO2) = 0.40 atm, p(O2) = 0.20 atm and p(SO3) = 0.80 atm. What is Kp?

    • 20 atm-1
    • 2.5 atm
    • 0.05 atm-1
    • 0.40 atm-1

  8. Which states of matter are omitted from the expression for Kp?

    • Gases only
    • Gases and liquids
    • Solids and liquids
    • Solids and gases

  9. What is the expression for Kp for the reaction CaCO3(s) ⇌ CaO(s) + CO2(g)?

    • p(CaO) / p(CaCO3)
    • p(CaO) × p(CO2) / p(CaCO3)
    • p(CO2)
    • p(CaCO3) / p(CO2)

  10. A gaseous equilibrium has Kp = 4.0 atm for A(g) ⇌ 2B(g). If p(A) = 0.50 atm, what is p(B) at equilibrium?

    • 1.41 atm
    • 2.00 atm
    • 0.25 atm
    • 8.0 atm

  11. Which factor changes the value of Kp for a specific equilibrium reaction?

    • Total pressure
    • Catalyst
    • Reactant concentrations
    • Temperature

  12. How does Kp relate to Kc for a gaseous equilibrium system?

    • Kp = Kc / RT
    • Kp = Kc ÷ (RT)^Δn
    • Kp = Kc + RT
    • Kp = Kc(RT)^Δn

  13. For the equilibrium 2NO(g) + O2(g) ⇌ 2NO2(g), what is the expression for Kp?

    • Kp = p(NO)^2 x p(O2) / p(NO2)^2
    • Kp = p(NO2)^2 / (p(NO)^2 x p(O2))
    • Kp = p(NO2) / (p(NO) x p(O2))
    • Kp = p(NO2)^2 / (p(NO) + p(O2))

  14. If the total pressure of an equilibrium mixture is 5.0 atm and the mole fraction of a gas is 0.20, what is its partial pressure?

    • 5.2 atm
    • 25 atm
    • 1.0 atm
    • 0.20 atm

  15. A gas mixture contains 0.40 mol of A and 0.60 mol of B in total. What is the mole fraction of A?

    • 0.67
    • 0.40
    • 0.60
    • 1.50

  16. For the equilibrium H2(g) + I2(g) ⇌ 2HI(g), what is the expression for Kp?

    • Kp = p(H2) x p(I2) / p(HI)^2
    • Kp = p(HI)^2 / (p(H2) x p(I2))
    • Kp = p(HI) / (p(H2) + p(I2))
    • Kp = p(HI)^2 / (p(H2) + p(I2))

  17. Why are partial pressures used instead of concentrations for gaseous equilibria in industrial processes?

    • Always larger values
    • Easier to measure
    • Increases catalyst speed
    • Eliminates temperature effects

  18. A mixture at equilibrium at 3.0 atm contains equal mole fractions of two gases. What is the partial pressure of each gas?

    • 6.0 atm
    • 1.5 atm
    • 0.50 atm
    • 3.0 atm

  19. What is the change in gas moles (products minus reactants) if Kp has units atm⁻¹?

    • +1
    • 0
    • -1
    • -2

  20. What is the expression for Kp for the equilibrium 2SO3(g) ⇌ 2SO2(g) + O2(g)?

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

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