Copper sulfate solution is electrolysed twice: first using graphite electrodes, then using two pure copper electrodes.
Statement 1: with graphite electrodes, the blue colour fades because copper ions are removed from the solution at the cathode
Statement 2: with graphite electrodes, the anode half equation is Cu→Cu2++2e−\mathrm{Cu \rightarrow Cu^{2+} + 2e^{-}}Cu→Cu2++2e−
Statement 3: with copper electrodes, oxygen gas is produced at the anode
Statement 4: with copper electrodes, the mass gained by the cathode equals the mass lost by the anode
Which statements are correct?
1 and 3 only
2 and 4 only
1 and 4 only
1, 2 and 4 only
52 exam-style questions on Edexcel GCSE Chemistry 4.2 Electrolytic processes, covering 4.2.1 Electrolytes and the process of electrolysis, 4.2.2 Products of electrolysis using inert electrodes, 4.2.3 Half equations, oxidation and reduction in electrolysis, and 4.2.4 Electrolysis of copper sulfate and purifying copper. Each one has a worked solution and a mark scheme showing where the marks go.