Electroplating (Cambridge (CIE) IGCSE Chemistry)
Revision Note
Written by: Alexandra Brennan
Reviewed by: Stewart Hird
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Electroplating
What is electroplating?
Electroplating is a process where the surface of one metal is coated with a layer of a different metal
The cathode / negative electrode is the object to be electroplated
The anode / positive electrode is made from the pure metal that will be plated onto the object
The electrolyte is an aqueous solution of a soluble salt of the pure metal at the anode
Electroplating a strip of iron with tin
A piece of iron being electroplated with tin. The electrolyte is tin(II) chloride, a water-soluble salt of tin
At the anode:
Tin atoms lose electrons to form tin ions in solution
The loss of electrons is oxidation
At the cathode:
Tin ions gain electrons to form tin atoms
The gain of electrons is reduction
The tin atoms are deposited on the strip of iron metal, coating it with a layer of tin
Examiner Tips and Tricks
Extended Tier students may be asked to write the ionic half equations for the reaction at each electrode. For the example above, these would be:
At the anode: Sn (s) → Sn2+ (aq) + 2e-
At the cathode: Sn2+ (aq) + 2e- → Sn (s)
What is electroplating used for?
Electroplating is done to make metals more resistant to corrosion or damage
e.g. chromium and nickel plating
e.g. galvanising - zinc plating / coating, typically done to iron and steel
It is also done to improve the appearance of metals,
e.g. coating cutlery and jewellery with silver
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