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1 markOxidation – Reduction Reactions

CSEC Chemistry · January 2020 · Paper 2 · Question 2(a)(v)

Oxidation and reduction occurring together is a REDOX reaction. Substances can be oxidizing or reducing agents. The REDOX reaction between aqueous copper (II) chloride and aqueous iodide is given by: 2Cu²⁺(aq) + 4I⁻(aq) → 2CuI(s) + I₂(aq).

Solution A was added to a small portion of an aqueous solution of potassium iodide in a test tube. The colourless potassium iodide turned brown. State whether Solution A contained an oxidizing agent or a reducing agent.

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Other parts of this question

  1. 2(a)(i)Define 'reduction' in terms of oxidation states.[1 mark]
  2. 2(a)(ii)Deduce the oxidation state of Cu in CuI.[1 mark]
  3. 2(a)(iii)Define the term 'oxidizing agent'.[2 marks]
  4. 2(a)(iv)With reference to the equation above, state, with a reason, which substance is acting as an oxidizing agent.[2 marks]
  5. 2(a)(vi)Explain your answer in (a) (v).[2 marks]
  6. 2(a)(vii)Write a balanced chemical equation to show the formation of the brown product in the reaction in (a) (v).[2 marks]
  7. 2(b)Describe what is observed with regard to the chemical reaction that occurs in the test tube.[2 marks]
  8. 2(c)One of the substances in the equation in (b) on page 11, is acting as a reducing agent. Describe a simple laboratory test that could be used to identify a…[2 marks]

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