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4.1.4Oxidation and reduction in terms of electrons

AQA GCSE Chemistry (8462), Higher tier · Chemical changes › Reactivity of metals

Practise Oxidation and reduction in terms of electrons. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.

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Quick recall

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Complete the sentences.
Oxidation is the .................... of electrons.
Reduction is the .................... of electrons.
loss; gain
Zinc displaces copper from copper(II) sulfate solution:
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) Write the ionic equation for this reaction.
Zn + Cu2+ → Zn2+ + Cu
When chlorine water is added to potassium bromide solution, the solution turns orange:
Cl2(aq) + 2KBr(aq) → 2KCl(aq) + Br2(aq) Write the ionic equation for this reaction.
Cl2 + 2Br− → 2Cl− + Br2
Complete the ionic equation.
Mg + Fe2+ → ....................
Mg2+ + Fe
Sodium atoms form sodium ions:
Na → Na+ + e−
Is this oxidation or reduction?
oxidation
Complete the half equation for the oxidation of zinc.
Zn → Zn2+ + ....
2e−

Sample questions

Written for this site in the style of AQA exam questions. They are not taken from real past papers.

Question 1Easy4 marks
Oxidation and reduction can be described in terms of electrons.
(a) Which statement describes reduction?
Tick (✓) one box.[1]
  • gain of electrons
  • loss of electrons
  • gain of protons
  • loss of neutrons
(b) Sodium atoms form sodium ions:
Na → Na+ + e−
Is this oxidation or reduction?[1]
(c) Complete the half equation.
Cl2 + 2e− → ....................[1]
(d) Magnesium reacts with copper(II) ions:
Mg + Cu2+ → Mg2+ + Cu
Which species loses electrons in this reaction?[1]
Show the answer and mark scheme
(a) Answer: gain of electrons
(b) Answer: oxidation
  • oxidation
(c) Answer: 2Cl−
  • 2Cl−
(d) Answer: magnesium atoms, Mg
  • magnesium / Mg
Question 2Medium5 marks
Oxidation and reduction can be described in terms of electrons.
(a) Complete the sentences.
Oxidation is the .................... of electrons.
Reduction is the .................... of electrons.[2]
(b) State whether each half equation shows oxidation or reduction.
Fe → Fe2+ + 2e−
Cl2 + 2e− → 2Cl−
Cu2+ + 2e− → Cu[3]
Show the answer and mark scheme
(a) Answer: loss; gain
  • loss
  • gain
(b) Answer: oxidation; reduction; reduction
  • Fe → Fe2+ + 2e−: oxidation
  • Cl2 + 2e− → 2Cl−: reduction
  • Cu2+ + 2e− → Cu: reduction
Question 3Hard7 marks
Zinc displaces copper from copper(II) sulfate solution:
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
(a) Write the ionic equation for this reaction.[2]
(b) Name the spectator ion in this reaction.[1]
(c) Write the two half equations for this reaction.[2]
(d) Identify the species that is oxidised and the species that is reduced. Explain your answer.[2]
Show the answer and mark scheme
(a) Answer: Zn + Cu2+ → Zn2+ + Cu
  • Zn + Cu2+ on the left
  • → Zn2+ + Cu on the right
(b) Answer: sulfate ion, SO42−
  • sulfate (ion) / SO42−
(c) Answer: Zn → Zn2+ + 2e− and Cu2+ + 2e− → Cu
  • Zn → Zn2+ + 2e−
  • Cu2+ + 2e− → Cu
(d)
  • zinc (atoms) are oxidised because they lose electrons
  • copper(II) ions are reduced because they gain electrons

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