Lesson 11.1.2

11.1.2 Temperature, pressure, catalysts and equilibrium Quiz: Pearson Edexcel Chemistry, Unit 11

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 11.1.2, Temperature, pressure, catalysts and equilibrium: 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. For an exothermic reaction, what happens to the value of Kc when temperature increases?

    • It decreases
    • It stays exactly the same
    • It increases
    • It doubles for every 10 K rise

  2. For an endothermic reaction, what effect does a temperature rise have on the equilibrium constant?

    • It increases, because the forward reaction absorbs heat
    • It becomes zero
    • It is unchanged, because temperature does not affect equilibrium
    • It decreases, because the reverse reaction absorbs heat

  3. Which change to a gaseous equilibrium at fixed temperature does NOT change the value of Kp?

    • Changing the enthalpy of the reaction
    • Changing the temperature
    • Changing the nature of the reaction
    • Increasing the total pressure

  4. In an exothermic reaction, a rise in temperature shifts the position of equilibrium. Which description is correct?

    • The position shifts to the right and Kp increases, because the heat supplied drives the reaction forward
    • The position shifts to the left, favouring reactants, and Kp decreases
    • The position does not change and Kp decreases, because temperature does not affect the equilibrium
    • The position shifts left and Kp increases, because a hotter system favours the reactants more strongly

  5. Why does a catalyst not change the position of equilibrium?

    • It speeds up the forward and reverse reactions equally, so Kp stays the same
    • It raises the enthalpy of the reaction, so the products become more stable at the new equilibrium
    • It removes the products from the mixture, so the equilibrium shifts to the right by removing product
    • It changes the stoichiometry of the reaction, which alters the balance of reactants and products

  6. For the equilibrium N2(g) + 3H2(g) ⇌ 2NH3(g), which change increases the equilibrium yield of ammonia by shifting the position to the right?

    • Increasing the temperature, because the reaction is exothermic and heat drives the forward direction
    • Adding a catalyst, because it changes Kp so that the yield of the ammonia product is increased
    • Decreasing the pressure, because it favours the side with more moles of gas in the equilibrium
    • Increasing the pressure, because there are fewer gas moles on the product side

  7. The Haber process is exothermic. Why is a compromise temperature used rather than the lowest possible temperature?

    • A lower temperature decreases the yield, so higher temperature is always chosen
    • A lower temperature has no effect on the yield or rate
    • A lower temperature increases the rate and decreases the yield at once
    • A lower temperature increases yield but slows the rate too much to be economic

  8. Why are catalysts used in the Haber process even though they do not change the equilibrium yield?

    • They increase the yield above the equilibrium value, so the catalyst gives more ammonia than the equilibrium allows
    • They change Kp to a higher value, which increases the yield at every temperature in the reactor
    • They remove nitrogen from the mixture, which drives the equilibrium toward the ammonia side
    • They allow equilibrium to be reached faster at a lower temperature

  9. For an equilibrium with 2 moles of gas on the left and 4 moles on the right, what is the effect of increasing the total pressure?

    • The position shifts to the right, favouring more gas moles
    • The position shifts to the left, favouring the side with fewer gas moles
    • Kp increases in proportion to the pressure
    • No effect on the position

  10. In the equilibrium N2O4(g) ⇌ 2NO2(g), which change shifts the equilibrium to the right?

    • Adding a catalyst
    • Adding argon at constant volume
    • Decreasing the total pressure
    • Increasing the total pressure

  11. What happens to the yield of an exothermic reaction if temperature is increased and the system is allowed to reach equilibrium?

    • The yield doubles
    • The yield of products increases
    • The yield is unaffected
    • The yield of products decreases

  12. Which compromise is typically required when balancing yield and rate for a reversible gas reaction?

    • A moderate temperature and pressure that give a reasonable yield at an economic rate
    • The highest possible temperature, regardless of yield, so that the reaction is as fast as the plant can achieve
    • The lowest possible pressure with no catalyst, so that the equipment is cheap and simple to run
    • The conditions that give zero rate but maximum yield, so that the product is never lost from the reactor

  13. Which factor makes a high-pressure process more expensive to run?

    • Pressure increases the activation energy, so more heat must be supplied to start each reaction
    • Pressure removes the product as a gas, so the product must be collected in a separate vessel
    • The catalyst is destroyed by pressure, so the process must use a fresh catalyst for every batch of gas
    • Strong equipment and energy are needed to compress the gases

  14. For an exothermic reaction at equilibrium, what does a decrease in temperature do to the value of Kp?

    • It makes Kp zero
    • It decreases the value of Kp
    • It has no effect on Kp
    • It increases the value of Kp

  15. A reaction has equal numbers of gas moles on both sides of the equation. What effect does increasing pressure have on the position of equilibrium?

    • It shifts to the right
    • No effect on the position
    • It makes the reaction stop
    • It shifts to the left

  16. Why is the effect of temperature on equilibrium explained by a change in the value of the equilibrium constant?

    • Temperature changes the mass of the catalyst, which then shifts the position of the equilibrium
    • Temperature changes the total volume of the container, which moves the equilibrium to a new position
    • Temperature changes the number of moles of gas present in the equilibrium mixture, altering the balance
    • Temperature changes the value of K, which then shifts the position of equilibrium

  17. For the exothermic equilibrium CO(g) + 2H2(g) ⇌ CH3OH(g), which conditions give the highest equilibrium yield of methanol?

    • High pressure and low temperature
    • High pressure and high temperature
    • Low pressure and high temperature
    • Low pressure and low temperature

  18. Which statement is a correct summary of Le Chatelier's principle?

    • A system at equilibrium always shifts toward the products
    • A system at equilibrium shifts to increase the value of Kc
    • A system at equilibrium is unaffected by any change in conditions
    • A system at equilibrium shifts to oppose an applied change

  19. Why does adding an inert gas at constant volume to a gaseous equilibrium not shift the position?

    • It removes the product from the mixture
    • It does not change the partial pressures of the reacting gases
    • It lowers the activation energy of the forward reaction
    • It increases the enthalpy of the reaction

  20. The equilibrium constant for an exothermic reaction is 10 at 500 K and 2 at 800 K. What does this show?

    • Kc falls as temperature rises, consistent with an exothermic reaction
    • Kc is unaffected by temperature
    • Kc rises as temperature rises, consistent with an exothermic reaction
    • The reaction must be endothermic

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