A student electrolyses sodium sulfate solution using graphite electrodes. The gas at each electrode is collected in a test tube. A few drops of universal indicator are added to the solution, which starts green.
Name the gas formed at each electrode.
After 10 minutes, 24 cm3\mathrm{cm^{3}}cm3 of gas has been collected at the cathode. Predict the volume of gas collected at the anode. Explain your answer.
The universal indicator near the cathode turns blue. Explain why.
Write the half equation for the reaction at the anode.
Explain why sodium sulfate is dissolved in the water instead of electrolysing pure water.
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.