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3.1 Introducing chemical reactions

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Question 16
H

Sodium sulfate solution is electrolysed using inert electrodes. Oxygen forms at the anode from hydroxide ions.

What is the balanced half equation for the reaction at the anode?

[1]
A

4OH−→O2+2H2O+4e−\mathrm{4OH^{-} \rightarrow O_{2} + 2H_{2}O + 4e^{-}}4OH−→O2​+2H2​O+4e−

B

4OH−→O2+2H2O+2e−\mathrm{4OH^{-} \rightarrow O_{2} + 2H_{2}O + 2e^{-}}4OH−→O2​+2H2​O+2e−

C

2OH−→O2+H2O+2e−\mathrm{2OH^{-} \rightarrow O_{2} + H_{2}O + 2e^{-}}2OH−→O2​+H2​O+2e−

D

4OH−+4e−→O2+2H2O\mathrm{4OH^{-} + 4e^{-} \rightarrow O_{2} + 2H_{2}O}4OH−+4e−→O2​+2H2​O

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3.1 Introducing chemical reactions Questions

  1. GCSE
  2. /Chemistry
  3. /3.1 Introducing chemical reactions

55 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.

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