Lesson 4.5.1.3

4.5.1.3 The energy change of reactions (HT only) Quiz: AQA Chemistry, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.5.1.3, The energy change of reactions (HT only): 20 multiple choice questions for the AQA GCSE Chemistry (8462), Unit 5: Energy changes, written with Revision Ninja.

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The 20 questions

  1. During a chemical reaction, energy is supplied to do what?

    • Break product bonds
    • Break reactant bonds
    • Form reactant bonds
    • Create atoms

  2. During a chemical reaction, energy is released when what happens?

    • Product bonds form
    • Product bonds break
    • Reactant bonds break
    • Reactant bonds form

  3. How is the overall energy change of a chemical reaction calculated from bond energies?

    • Total bonds added together
    • Activation energy minus heat
    • Bonds formed minus broken
    • Bonds broken minus formed

  4. In an exothermic reaction, how does bond-forming energy compare to bond-breaking energy?

    • Energies are equal
    • Greater energy needed
    • No energy involved
    • Greater energy released

  5. In an endothermic reaction, how does bond-breaking energy compare to bond-forming energy?

    • Energies are equal
    • Greater energy released
    • No energy involved
    • Greater energy needed

  6. Higher tier: Bond energies are: H-H 436, Cl-Cl 242, H-Cl 431 kJ/mol. For H2 + Cl2 -> 2HCl, what is the overall energy change?

    • -1298 kJ/mol
    • +678 kJ/mol
    • -184 kJ/mol
    • +184 kJ/mol

  7. Higher tier: Using H-H = 436 and O=O = 498 kJ/mol, what is the total energy needed to break 2 mol H-H and 1 mol O=O?

    • 872 kJ
    • 1370 kJ
    • 498 kJ
    • 934 kJ

  8. Higher tier: O-H bond energy is 463 kJ/mol. Forming 2 mol of water, which contains 4 O-H bonds, releases how much energy?

    • 2315 kJ
    • 463 kJ
    • 1852 kJ
    • 926 kJ

  9. Higher tier: Using H-H = 436, O=O = 498 and O-H = 463 kJ/mol, what is the overall energy change for 2H2 + O2 -> 2H2O?

    • -482 kJ
    • +3222 kJ
    • -1370 kJ
    • +482 kJ

  10. Higher tier: A reaction needs 350 kJ to break bonds and releases 300 kJ forming bonds. What type of reaction is it?

    • Endothermic
    • Catalysed
    • Exothermic
    • Neutral

  11. Which expression gives the correct calculation for overall reaction energy change?

    • Sum formed minus broken
    • Sum of bonds multiplied
    • Sum broken minus formed
    • Sum of activation energies

  12. Higher tier: Energy broken is 500 kJ and energy formed is 600 kJ. What is the overall energy change, and what type of reaction is it?

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

  13. What is bond energy defined as the energy needed to do?

    • Form a specific bond
    • Break a specific bond
    • Melt a solid
    • Heat a compound

  14. Higher tier: The H-Cl bond energy is 431 kJ/mol. Forming 2 mol of H-Cl releases how much energy?

    • 215 kJ
    • 862 kJ
    • 1293 kJ
    • 431 kJ

  15. What energy change is always associated with breaking chemical bonds?

    • Energy release
    • Energy input
    • Thermal destruction
    • No energy change

  16. What happens to energy when chemical bonds are broken?

    • Energy is created
    • Energy is destroyed
    • Energy is absorbed
    • Energy is released

  17. Higher tier: Energy needed to break four C-H bonds at 413 kJ/mol each is:

    • 1652 kJ
    • 826 kJ
    • 2065 kJ
    • 413 kJ

  18. Higher tier: If energy to break bonds is 1652 kJ and energy released forming bonds is 2000 kJ, what is the overall energy change?

    • -348 kJ, exothermic
    • -348 kJ, endothermic
    • +348 kJ, exothermic
    • +348 kJ, endothermic

  19. Which bond energy values indicate an exothermic chemical reaction?

    • Broken 900 kJ, formed 950 kJ
    • Broken 0 kJ, formed 100 kJ
    • Broken 950 kJ, formed 900 kJ
    • Broken 500 kJ, formed 500 kJ

  20. Higher tier: A reaction needs 1000 kJ to break bonds and releases 1100 kJ forming bonds. How much energy is transferred to the surroundings?

    • 100 kJ absorbed
    • 100 kJ released
    • 1100 kJ absorbed
    • 1000 kJ released

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