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Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section

Electrolysis and redox

19 practice questions

Start practising (8 questions)

Practice questions

1–8 of 8 · Normal

  1. Question 1

    2 marks · Normal

    State what is meant by:

    (a)

    oxidation, in terms of electron transfer.

    [1 mark]
    (b)

    reduction, in terms of electron transfer.

    [1 mark]
    Answer and see the solution →

  2. Question 2

    4 marks · Normal

    The diagram shows an apparatus used in the electrolysis of molten lead(II) iodide. The electrodes and power supply are labelled.

    (a)

    Explain what is meant by 'discharging an ion' during electrolysis.

    [2 marks]
    (b)

    State what happens to the lead(II) ions at the cathode, referring to electron transfer.

    [1 mark]
    (c)

    Write the ionic half-equation for the reaction at the anode.

    [1 mark]
    Answer and see the solution →

  3. Question 3

    3 marks · Normal

    The electrolysis of molten potassium chloride (KCl) produces potassium metal and chlorine gas.

    (a)

    Write the half-equation for the reaction at the cathode.

    [1 mark]
    (b)

    State whether the reaction at the cathode is oxidation or reduction.

    [1 mark]
    (c)

    Explain your answer to part (b) in terms of electron transfer.

    [1 mark]
    Answer and see the solution →

  4. Question 4

    3 marks · Normal

    A student wants to remember whether oxidation or reduction involves losing or gaining electrons.

    (a)

    State the mnemonic used to remember this.

    [1 mark]
    (b)

    What does each letter in the mnemonic stand for?

    [1 mark]
    (c)

    Explain, using the mnemonic, what happens to an ion that gains electrons.

    [1 mark]
    Answer and see the solution →

  5. Question 5

    4 marks · Normal

    Table 1: Electrode Reactions
    IonHalf-equation
    Cl^-2Cl^- \rightarrow Cl_2 + 2e^-
    Ag^+Ag^+ + e^- \rightarrow Ag
    Fe^{3+}Fe^{3+} + 3e^- \rightarrow Fe
    O^{2-}2O^{2-} \rightarrow O_2 + 4e^-

    Study Table 1. For each reaction below, state whether the ion is oxidised or reduced and explain why using electron transfer.

    (a)

    Cl^- \rightarrow Cl_2 + 2e^-

    [1 mark]
    (b)

    Ag^+ + e^- \rightarrow Ag

    [1 mark]
    (c)

    Fe^{3+} + 3e^- \rightarrow Fe

    [1 mark]
    (d)

    O^{2-} \rightarrow O_2 + 4e^-

    [1 mark]
    Answer and see the solution →

  6. Question 6

    1 mark · Normal

    In the electrolysis of molten zinc bromide, what does it mean to 'discharge' a zinc ion (Zn^{2+}) at the cathode?

    1. A.Zinc ions lose electrons to form zinc atoms.
    2. B.Zinc ions gain electrons to form zinc atoms.
    3. C.Zinc atoms lose electrons to form zinc ions.
    4. D.Zinc ions are removed from the solution by evaporation.
    Answer and check →

  7. Question 7

    2 marks · Normal

    For the electrolysis of molten calcium bromide (CaBr_2):

    (a)

    Which electrode (anode or cathode) is the site of oxidation?

    [1 mark]
    (b)

    Which electrode reaction involves reduction?

    [1 mark]
    Answer and see the solution →

  8. Question 8

    4 marks · Normal

    You are asked to explain how the OILRIG mnemonic helps when deciding whether a reaction is oxidation or reduction.

    (a)

    Write what each letter in OILRIG stands for.

    [2 marks]
    (b)

    Use the mnemonic to decide whether the following process is oxidation or reduction: Fe^{2+} gains 2 electrons to form Fe.

    [1 mark]
    (c)

    State how the mnemonic helps you to answer part (b).

    [1 mark]
    Answer and see the solution →