A student electrolyses copper sulfate solution using copper electrodes. The table shows the mass gained by the cathode when different currents are passed for 30 minutes.
| Current / A | Mass gained by cathode / g |
|---|---|
| 0.20 | 0.12 |
| 0.40 | 0.24 |
| 0.60 | 0.36 |
| 0.80 | 0.47 |
Write the half equation for the reaction at the anode.
Explain why the reaction at the anode is an oxidation.
The mass of copper deposited is directly proportional to both the current and the time. Determine the mass of copper deposited by a current of 0.40 A in 45 minutes.
In industry, an impure copper anode loses more mass than the pure copper cathode gains. Explain why.
Devise a method the student could use to obtain the results in the table.
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.