A student places a piece of filter paper soaked in sodium chloride solution on a microscope slide. A metal clip is attached to each end of the paper and connected to a low voltage d.c. power supply.
A drop of a solution containing blue copper ions, Cu2+\mathrm{Cu^{2+}}Cu2+, and purple manganate(VII) ions, MnO4−\mathrm{MnO_{4}^{-}}MnO4−, is placed in the centre of the paper.
State what is meant by electrolysis.
Predict the direction in which the blue colour moves. Explain your answer.
State the name given to negatively charged ions.
Explain why the filter paper is soaked in sodium chloride solution.
The student reverses the connections to the power supply. Describe what happens to the coloured ions.
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.