A student electrolyses two unfamiliar solutions using graphite electrodes: silver nitrate solution, AgNO3(aq)\mathrm{AgNO_{3}(aq)}AgNO3(aq), and potassium iodide solution, KI(aq)\mathrm{KI(aq)}KI(aq).
The reactivity series includes: potassium > sodium > zinc > hydrogen > copper > silver
Predict the product at each electrode when silver nitrate solution is electrolysed.
Predict the product at each electrode when potassium iodide solution is electrolysed.
Explain why the product at the cathode is different for the two solutions.
Write half equations for the reaction at the cathode in silver nitrate solution and at the anode in potassium iodide solution.
After electrolysis, the solution left from potassium iodide turns red litmus paper blue. Explain why.
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.