Lesson 5.5.1.3

5.5.1.3 The energy change of reactions (HT only) Quiz: AQA Combined Science, Unit 12

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.5.1.3, The energy change of reactions (HT only): 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 12: Energy changes, written with Revision Ninja.

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The 20 questions

  1. During a chemical reaction, energy must be ___ to break bonds in the reactants and is ___ when bonds in the products form.

    • Supplied; absorbed
    • Released; supplied
    • Supplied; released
    • Released; absorbed

  2. What is calculated by subtracting energy released forming product bonds from energy needed to break reactant bonds?

    • Activation energy
    • Enthalpy release
    • Total bond energy
    • Overall energy change

  3. A reaction releases more energy forming new bonds than it takes to break old bonds. The reaction is:

    • Neutral
    • Reversible
    • Exothermic
    • Endothermic

  4. Which reaction type has a greater energy needed for breaking bonds than forming them?

    • Catalysed
    • Neutralisation
    • Exothermic
    • Endothermic

  5. What values are required to calculate the energy change of a reaction?

    • Surrounding temperatures
    • Activation energies only
    • Bond energies
    • Reaction rates

  6. A reaction has a negative overall energy change. What type of reaction is it?

    • Exothermic
    • Thermal decomposition
    • Endothermic
    • Neutralisation

  7. Which term describes a reaction with a positive overall energy change?

    • Exothermic
    • Catalysed
    • Endothermic
    • Equilibrium

  8. For H2 + Cl2 to 2HCl, bond energies are H-H 436, Cl-Cl 242 and H-Cl 431 kJ/mol. What is the overall energy change?

    • -184 kJ/mol
    • +678 kJ/mol
    • +184 kJ/mol
    • -862 kJ/mol

  9. For CH4 + 2O2 to CO2 + 2H2O, bond energies are C-H 413, O=O 498, C=O 805 and O-H 464 kJ/mol. What is the overall energy change?

    • -3466 kJ/mol
    • +2648 kJ/mol
    • -818 kJ/mol
    • +818 kJ/mol

  10. Breaking bonds needs 1500 kJ and forming bonds releases 1800 kJ. What is the overall energy change?

    • -300 kJ, exothermic
    • +3300 kJ, endothermic
    • +300 kJ, endothermic
    • -3300 kJ, exothermic

  11. A reaction has an energy change of +75 kJ/mol. What happens to the surroundings?

    • Get colder
    • Get hotter
    • Increase pressure
    • Stay constant

  12. Breaking bonds needs 950 kJ and forming bonds releases 870 kJ. Which describes the reaction?

    • Endothermic, +80 kJ
    • Exothermic, -80 kJ
    • Exothermic, -1820 kJ
    • Endothermic, +1820 kJ

  13. Breaking bonds requires 2100 kJ and forming bonds releases 2100 kJ. What is the energy change?

    • 0 kJ
    • 4200 kJ
    • 2100 kJ
    • -2100 kJ

  14. Breaking 4 bonds of type X (300 kJ each) and forming 3 bonds of type Y (450 kJ each). What is the overall energy change?

    • +150 kJ
    • +2550 kJ
    • -150 kJ
    • -1350 kJ

  15. For N2 + 3H2 to 2NH3, bond energies are N triple bond N 944, H-H 436 and N-H 391 kJ/mol. What is the overall energy change?

    • +2252 kJ/mol
    • -94 kJ/mol
    • +94 kJ/mol
    • -2346 kJ/mol

  16. Breaking bonds needs 1100 kJ and forming bonds releases 1000 kJ. Which describes the energy change?

    • -2100 kJ, exothermic
    • -100 kJ, exothermic
    • +100 kJ, endothermic
    • +2100 kJ, endothermic

  17. Breaking bonds needs 2400 kJ and forming bonds releases 2100 kJ. Which describes the reaction?

    • Endothermic, +300 kJ
    • Exothermic, +300 kJ
    • Exothermic, -300 kJ
    • Endothermic, -300 kJ

  18. Breaking bonds needs 1500 kJ and forming bonds gives 1300 kJ. If forming energy increases by 400 kJ, the new overall energy change is:

    • +200 kJ
    • -200 kJ
    • +400 kJ
    • -400 kJ

  19. For H2 + Cl2 to 2HCl with an overall energy change of -184 kJ, the energy change per mole of HCl formed is:

    • -368 kJ/mol HCl
    • -92 kJ/mol HCl
    • -184 kJ/mol HCl
    • +92 kJ/mol HCl

  20. Which bond energy values indicate an exothermic reaction?

    • Break 1350 kJ, form 1200 kJ
    • Break 1200 kJ, form 1200 kJ
    • Break 1200 kJ, form 1350 kJ
    • Break 1500 kJ, form 1350 kJ

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