During the purification of copper, the pure copper cathode gains 3.175 g in mass.
Relative atomic mass: Cu = 63.5
Avogadro constant = 6.02 × 1023 per mole
How many electrons were transferred to the cathode?
3.01×10223.01\times10^{22}3.01×1022
6.02×10226.02\times10^{22}6.02×1022
1.20×10231.20\times10^{23}1.20×1023
1.91×10241.91\times10^{24}1.91×1024
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.