Lesson 5.1.2

5.1.2 How far Quiz: OCR Chemistry, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 5.1.2, How far: 20 multiple choice questions for the OCR Chemistry (H432), Unit 4: Physical chemistry and transition elements, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. How is the mole fraction of a gas in a mixture calculated?

    • Component moles ÷ total
    • Component moles ÷ volume
    • Total moles ÷ component
    • Component moles × pressure

  2. How is the partial pressure of a gas in a mixture calculated?

    • Mole fraction ÷ pressure
    • Mole fraction × pressure
    • Pressure ÷ mole fraction
    • Mole fraction × volume

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

    • mol^-1 dm^3
    • mol^2 dm^-6
    • mol dm^-3
    • mol^-2 dm^6

  4. Why are pure solids omitted from heterogeneous equilibrium Kc expressions?

    • Temperature fluctuates
    • They are unreactive
    • Mass remains zero
    • Concentration is constant

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

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

  6. How does increasing temperature affect the Kc value of an exothermic reaction?

    • Stays the same
    • Doubles
    • Decreases
    • Increases

  7. Where does the position of equilibrium lie if the value of Kc is very large?

    • In the centre
    • To the left
    • To the right
    • At the start

  8. Initially 1.0 mol of H2 and 1.0 mol of I2 are placed in a 1.0 dm^3 vessel. At equilibrium 0.20 mol of H2 and 0.20 mol of I2 remain, with 1.60 mol of HI present. What is Kc for H2 + I2 <=> 2HI?

    • 3.2
    • 8.0
    • 64
    • 0.125

  9. At equilibrium N2O4(g) <=> 2NO2(g), the partial pressures are p(N2O4) = 0.60 atm and p(NO2) = 0.80 atm. What is Kp?

    • 0.75 atm
    • 1.1 atm
    • 2.1 atm
    • 0.48 atm

  10. A gas mixture at equilibrium contains 0.40 mol of CO and 0.60 mol of H2 out of a total of 1.00 mol. What is the mole fraction of CO?

    • 0.40
    • 0.60
    • 0.67
    • 0.24

  11. The total pressure of an equilibrium mixture is 200 kPa and the mole fraction of CO is 0.25. What is the partial pressure of CO?

    • 80 kPa
    • 25 kPa
    • 200 kPa
    • 50 kPa

  12. 1.0 mol of PCl5 is placed in a 1.0 dm^3 vessel and at equilibrium PCl5 <=> PCl3 + Cl2 contains 0.40 mol of PCl5. What is Kc?

    • 0.90 mol dm^-3
    • 0.60 mol dm^-3
    • 0.36 mol dm^-3
    • 1.5 mol dm^-3

  13. For the equilibrium C(s) + CO2(g) <=> 2CO(g), which expression is correct for Kc?

    • Kc = [CO]^2 / ([C][CO2])
    • Kc = [CO] / [CO2]
    • Kc = [CO2] / [CO]^2
    • Kc = [CO]^2 / [CO2]

  14. If gas mole numbers are equal on both sides of a reaction, how do Kp and Kc compare?

    • Kp is zero
    • Kc is larger
    • Kp is larger
    • They are equal

  15. For 2SO2(g) + O2(g) <=> 2SO3(g), a mixture starts with 2.0 mol SO2 and 1.0 mol O2 in 1.0 dm^3. At equilibrium 1.6 mol SO3 is present. What is Kc, given SO2 = 0.40 mol dm^-3 and O2 = 0.20 mol dm^-3?

    • 1.6 mol^-1 dm^3
    • 0.0125 dm^3 mol^-1
    • 80 dm^3 mol^-1
    • 8.0 dm^3 mol^-1

  16. What does a Kc value of 1 × 10^-8 indicate about the equilibrium position?

    • In the centre
    • Far to right
    • At start
    • Far to left

  17. Which change will increase the value of Kc for an endothermic forward reaction?

    • Decreasing temperature
    • Increasing pressure
    • Adding catalyst
    • Increasing temperature

  18. What is the only factor that alters the numerical value of Kc?

    • Catalyst
    • Concentration
    • Pressure
    • Temperature

  19. For the equilibrium 2NO(g) + O2(g) <=> 2NO2(g), which expression gives Kc?

    • [NO2] / ([NO] [O2])
    • [NO2]^2 / ([NO]^2 [O2])
    • [NO2]^2 / ([NO] [O2])
    • [NO]^2 [O2] / [NO2]^2

  20. How does increasing total pressure affect the equilibrium position for N2O4(g) ⇌ 2NO2(g)?

    • No change
    • Shifts right
    • Shifts left
    • Fluctuates

All OCR Chemistry quizzes