5.6.2.6 The effect of temperature changes on equilibrium (HT only) Quiz: AQA Combined Science, Unit 13

The 20 questions

1. What happens to the relative amount of products when an endothermic equilibrium is heated?

   • Decreases
   • Drops to zero
   • Increases
   • Stays constant

2. Raising the temperature of an exothermic equilibrium: the relative amount of products:

   • Decreases
   • Doubles
   • Increases
   • Stays the same

3. Lowering the temperature of an endothermic equilibrium: the relative amount of products:

   • Decreases
   • Becomes zero
   • No change
   • Increases

4. Lowering the temperature of an exothermic equilibrium: the relative amount of products:

   • Decreases
   • No change
   • Increases
   • Becomes zero

5. To favour products in an exothermic reaction, the temperature should be:

   • Kept the same
   • Lowered
   • Raised then lowered
   • Raised

6. Forward reaction has an energy change of +92 kJ/mol. Raising the temperature shifts equilibrium:

   • Not at all
   • Towards the catalyst
   • Towards reactants
   • Towards products

7. Forward reaction is exothermic (-92 kJ/mol). Which change favours the reactants?

   • Adding more reactant
   • Decreasing the temperature
   • Removing product
   • Increasing the temperature

8. At 300 degrees C the product is 40%; at 400 degrees C it is 25%. The forward reaction is:

   • Exothermic
   • Endothermic
   • Catalysed
   • Neutral

9. At 200 degrees C the product is 60%; at 350 degrees C it is 80%. The forward reaction is:

   • Irreversible
   • Endothermic
   • Neutral
   • Exothermic

10. Why might a low temperature not be used for an exothermic reaction despite higher yield?

    • Yield is lower
    • Catalyst melts
    • Pressure drops
    • Rate is slower

11. How does an endothermic equilibrium system respond when heated?

    • Favours reverse direction
    • Stops completely
    • Decomposes instantly
    • Favours forward direction

12. What determines how temperature changes shift an equilibrium position?

    • Total pressure
    • Vessel volume
    • Catalyst presence
    • Energy change

13. If decreasing temperature shifts equilibrium to the right, what type of reaction is the forward process?

    • Neutral
    • Exothermic
    • Catalysed
    • Endothermic

14. If yield falls as temperature rises, which direction is favoured by higher temperature?

    • Reverse endothermic
    • Forward endothermic
    • Forward exothermic
    • Neither direction

15. For X to Y, [Y] rises when temperature rises at equilibrium. The forward reaction is:

    • Exothermic
    • Catalysed
    • Endothermic
    • Neutral

16. What two factors does a compromise temperature balance in an industrial process?

    • Pressure and volume
    • Yield and rate
    • Volume and density
    • Cost and mass

17. What happens when you cool a system with an endothermic forward reaction?

    • Equilibrium stops
    • No change
    • Reverse favoured
    • Forward favoured

18. Why does heating an endothermic equilibrium system increase the amount of product?

    • Increases pressure
    • Removes reactants
    • Absorbs extra heat
    • Speeds up catalysts

19. The forward energy change is -150 kJ. The reverse energy change is:

    • +150 kJ
    • +300 kJ
    • -150 kJ
    • 0 kJ

20. Which temperature adjustment favours ammonia production in the Haber process?

    • Absolute zero
    • Constant temperature
    • Higher temperature
    • Lower temperature

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