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3.1 Introducing chemical reactions

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Question 15
H

Molten lead bromide, PbBr2\mathrm{PbBr_{2}}PbBr2​, is electrolysed using inert electrodes. Bromine forms at the anode.

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

[1]
A

2Br−+2e−→Br2\mathrm{2Br^{-} + 2e^{-} \rightarrow Br_{2}}2Br−+2e−→Br2​

B

Br−→Br+e−\mathrm{Br^{-} \rightarrow Br + e^{-}}Br−→Br+e−

C

2Br−→Br2+2e−\mathrm{2Br^{-} \rightarrow Br_{2} + 2e^{-}}2Br−→Br2​+2e−

D

Pb2++2e−→Pb\mathrm{Pb^{2+} + 2e^{-} \rightarrow Pb}Pb2++2e−→Pb

Markscheme

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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