Lesson 4.4.3.5

4.4.3.5 Representation of reactions at electrodes as half equations (HT only) Quiz: AQA Chemistry, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.4.3.5, Representation of reactions at electrodes as half equations (HT only): 20 multiple choice questions for the AQA GCSE Chemistry (8462), Unit 4: Chemical changes, written with Revision Ninja.

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The 20 questions

  1. What do positively charged ions do at the cathode during electrolysis?

    • Gain electrons
    • Lose electrons
    • Lose neutrons
    • Gain protons

  2. Higher tier: Electrode reactions in which ions gain electrons are called:

    • Hydrolyses
    • Oxidations
    • Reductions
    • Neutralisations

  3. Higher tier: Which half equation represents hydrogen formation at the cathode?

    • H2 -> 2H+ + 2e-
    • 2H+ + 2e- -> H2
    • 2OH- -> H2O + O2
    • O2 + 4e- -> 2O2-

  4. Higher tier: Which half equation correctly shows oxygen formation at the anode from hydroxide ions?

    • 4OH- -> O2 + 2H2O + 4e-
    • 4OH- -> O2 + 2H2O + 2e-
    • O2 + 4e- -> 2O2-
    • O2 + 2H2O + 4e- -> 4OH-

  5. Higher tier: Which half equation shows chloride ions forming chlorine at the anode?

    • Cl- -> Cl + e-
    • 2Cl- -> Cl2 + 2e-
    • Cl2 + 2e- -> 2Cl-
    • 2Cl- + 2e- -> Cl2

  6. Higher tier: Which half equation shows lead ions being discharged at the cathode?

    • Pb2+ -> Pb + 2e-
    • Pb + 2e- -> Pb2-
    • Pb -> Pb2+ + 2e-
    • Pb2+ + 2e- -> Pb

  7. Higher tier: Which half equation shows bromide ions being discharged?

    • Br2 + 2e- -> 2Br-
    • 2Br- -> Br2 + 2e-
    • 2Br- + 2e- -> Br2
    • Br- + e- -> Br

  8. Higher tier: On which side of an anode half equation are the electrons shown?

    • Both sides
    • Right side
    • Not shown
    • Left side

  9. What two features must a correct half equation balance?

    • Mass and volume
    • Moles and density
    • Energy and pressure
    • Atoms and charge

  10. Higher tier: Electrons written on the left side of a half equation show:

    • Precipitation
    • Reduction
    • Oxidation
    • Neutralisation

  11. Higher tier: In 4OH- -> O2 + 2H2O + 4e-, how many electrons are released?

    • 4
    • 2
    • 8
    • 6

  12. Higher tier: In 2H+ + 2e- -> H2, how many electrons are gained?

    • 4
    • 1
    • 2
    • 0

  13. Higher tier: Which half equation applies at the cathode in molten sodium chloride?

    • Na -> Na+ + e-
    • Na+ + e- -> Na
    • Na+ -> Na2+ + e-
    • Cl- -> Cl + e-

  14. Higher tier: Which species is oxidised at the anode when oxygen is produced in aqueous electrolysis?

    • Hydroxide ions
    • Hydrogen ions
    • Metal ions
    • Oxygen gas

  15. Higher tier: Which is the reduction half equation for silver during electrolysis of silver nitrate?

    • Ag2 -> 2Ag+ + 2e-
    • Ag+ -> Ag2+ + e-
    • Ag+ + e- -> Ag
    • Ag -> Ag+ + e-

  16. Higher tier: Which half equation describes oxide ions forming oxygen at the anode in aluminium extraction?

    • Al3+ + 3e- -> Al
    • O2 + 4e- -> 2O2-
    • 2O2- -> O2 + 4e-
    • Al -> Al3+ + 3e-

  17. Higher tier: Which half equation describes aluminium ions at the cathode?

    • Al3+ + e- -> Al
    • Al3+ + 3e- -> Al
    • Al + 3e- -> Al3-
    • Al -> Al3+ + 3e-

  18. What happens to hydrogen ions at the cathode during electrolysis?

    • Reduced
    • Sublimed
    • Neutralised
    • Oxidised

  19. Higher tier: Which half equation is correctly balanced?

    • H+ + e- -> H2
    • H+ + 2e- -> H2
    • 2H+ + e- -> H2
    • 2H+ + 2e- -> H2

  20. Higher tier: At the anode in electrolysis forming chlorine, what is the species on the left side?

    • Chlorine atoms
    • Hydrogen ions
    • Electrons
    • Chloride ions

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