a) Some metal objects are electroplated to improve their appearance - Edexcel - GCSE Chemistry - Question 5 - 2014 - Paper 1

During electrolysis, the impure copper anode dissolves, and copper ions are transferred to the pure copper cathode.

1. The impure copper anode loses mass as copper ions dissolve into the electrolytic solution and are carried to the cathode. This explains the 5.0 g decrease in the mass of the impure copper anode.

2. The pure copper cathode gains mass due to the deposition of copper ions from the solution. The increase of 4.8 g in the mass of the pure copper cathode corresponds to the number of copper ions that were reduced during electrolysis.

3. Impurities from the anode may also affect the mass change, but the significant mass changes indicate that the copper ions are primarily responsible for the changes observed in both electrodes.