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1 markOxidation – Reduction Reactions

CSEC Chemistry · May/June 2012 · Paper 2 · Question 2(a)

Figure 3 shows a simplified diagram of the apparatus used for the electrolysis of aqueous copper(II) sulphate, CuSO4, using platinum electrodes.

Deduce the oxidation state of sulphur in CuSO4.

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Other parts of this question

  1. 2(b)At the anode, the hydroxide ions are discharged in preference to the sulphate ions. State a reason for this.[1 mark]
  2. 2(c)Write a balanced equation for the reaction at the anode.[2 marks]
  3. 2(d)From the equation written in (c) above, state whether the reaction at the anode is oxidation or reduction. Give an explanation for your answer.[1 mark]
  4. 2(e)State TWO changes that occur in the electrolyte.[2 marks]
  5. 2(f)Determine the mass of copper (in grams) which will be deposited at the cathode when 5A of current passes through the electrolytic cell for half an hour.…[4 marks]
  6. 2(g)Indicate below how the apparatus in Figure 3 can be modified to obtain pure copper from impure copper. If no modification is required write “no modification…[3 marks]

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