A student investigated the electrolysis of copper sulfate solution using copper electrodes for 15 minutes.
Their results are shown in the table below:
| Anode | Cathode | |
|---|---|---|
| Mass of electrode before electrolysis in g | 5.85 | 5.10 |
| Mass of electrode after electrolysis in g | 5.21 | 5.72 |
| Change in mass in g | −0.64 | +0.62 |
The electrolysis was repeated with a fresh cell using another pair of copper electrodes of the same starting masses.
Explain a change that could be made to the apparatus or circuit to cause the mass of the cathode to increase by 1.86 g in the same 15-minute period.
83 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.