Copper(II) sulfate solution is electrolysed using graphite electrodes until the blue colour has disappeared.
What happens to the pH of the solution, and why?
It decreases, because H+\mathrm{H^{+}}H+ ions and SO42−\mathrm{SO_{4}^{2-}}SO42− ions are left in the solution
It increases, because OH−\mathrm{OH^{-}}OH− ions are left in the solution
It stays the same, because the SO42−\mathrm{SO_{4}^{2-}}SO42− ions are not discharged
It increases, because H+\mathrm{H^{+}}H+ ions are discharged at the cathode
98 exam-style questions on OCR GCSE Chemistry 3.4 Electrolysis, covering 3.4.1 Products formed at the electrodes in electrolysis and 3.4.2 The technique of electrolysis. Each one has a worked solution and a mark scheme showing where the marks go.