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Transition metals (A-level only)

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Question 5

Iron(II) ions, Fe2+\text{Fe}^{2+}Fe2+, can act as a homogeneous catalyst in the reaction between peroxodisulfate ions, S2O82−\text{S}_2\text{O}_8^{2-}S2​O82−​, and iodide ions, I−\text{I}^-I−.

Which of the following equations represents the step in this catalytic mechanism in which the iron catalyst is oxidized?

A

2I−+2Fe3+→I2+2Fe2+2\text{I}^- + 2\text{Fe}^{3+} \rightarrow \text{I}_2 + 2\text{Fe}^{2+}2I−+2Fe3+→I2​+2Fe2+

B

S2O82−+2Fe2+→2SO42−+2Fe3+\text{S}_2\text{O}_8^{2-} + 2\text{Fe}^{2+} \rightarrow 2\text{SO}_4^{2-} + 2\text{Fe}^{3+}S2​O82−​+2Fe2+→2SO42−​+2Fe3+

C

S2O82−+2Fe3+→2SO42−+2Fe4+\text{S}_2\text{O}_8^{2-} + 2\text{Fe}^{3+} \rightarrow 2\text{SO}_4^{2-} + 2\text{Fe}^{4+}S2​O82−​+2Fe3+→2SO42−​+2Fe4+

D

S2O82−+2I−→2SO42−+I2\text{S}_2\text{O}_8^{2-} + 2\text{I}^- \rightarrow 2\text{SO}_4^{2-} + \text{I}_2S2​O82−​+2I−→2SO42−​+I2​

Markscheme

Transition metals (A-level only) Questions

  1. A Level
  2. /Chemistry
  3. /Transition metals (A-level only)

63 exam-style questions on AQA A Level Chemistry Transition metals (A-level only), covering General properties of transition metals (A-level only), Substitution reactions (A-level only), Shapes of complex ions (A-level only), Formation of coloured ions (A-level only), Variable oxidation states (A-level only), and Catalysts (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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