Electrolytic processes
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Impure silver can be purified using electrolysis in a process called electrorefining.

In this setup:

  • the anode is made of impure silver
  • the cathode is made of pure silver
  • the electrolyte is silver nitrate solution.

The apparatus at the start of the experiment is shown in the diagram below:

Diagram of an electrolysis cell for purifying silver. It shows a beaker containing silver nitrate solution. On the left is a thick impure silver anode connected to the positive terminal of a d.c. power supply. On the right is a thin pure silver cathode connected to the negative terminal. Underneath the anode, space is indicated for sludge to accumulate.

During the electrolysis, three major observations are made:

  1. The mass of the anode decreases while the mass of the cathode increases.
  2. A solid residue (sludge) collects on the bottom of the beaker directly beneath the anode.
  3. The concentration of silver ions in the silver nitrate solution remains constant.

Explain all three observations.

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Electrolytic processes Questions

Practise Edexcel GCSE Chemistry Electrolytic processes with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

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Electrolytic processes Questions

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