Cambridge O Level Chemistry · Syllabus 5070 · Electrochemistry
Electroplating
What is Electroplating?
The use of electrolysis to coat a metal object with a thin layer of another metal. The object being plated is made the negative cathode, the coating metal is made the positive anode, and the electrolyte is a solution containing ions of the coating metal; those ions are reduced onto the object. It is done to improve the object's appearance or its resistance to corrosion.
This definition is part of the Electrochemistry chapter in Cambridge O Level Chemistry.
Examiner tips on Electroplating
- The two purposes, in the syllabus's words. Electroplating can improve a metal object's appearance, and it can improve its resistance to corrosion. A question asking for the reasons wants those two, and either one alone is half an answer.
Questions students ask about Electroplating
Which electrode do you connect the object to when electroplating?
The object being plated is made the negative cathode. Metal ions from the electrolyte are reduced onto the object, and reduction happens at the cathode, so connecting the object to the positive terminal would be wrong. The coating metal is made the positive anode, and the electrolyte is a solution containing ions of the coating metal. Electroplating is done for two reasons, and a question asking why wants both: to improve the appearance of a metal object and to improve its resistance to corrosion.