Electroplating is an important industrial use of electrolysis. An iron key is to be plated with nickel. (a) Explain what is meant by the term electroplating...
Question 1 Report
Electroplating is an important industrial use of electrolysis. An iron key is to be plated with nickel.
(a) Explain what is meant by the term electroplating. [2]
(b) State two reasons why objects are electroplated. [2]
(c) For the plating of the iron key with nickel, state whether the key is the anode or the cathode, and name the metal used as the other electrode. [2]
Answer Details
This question tests the idea and purpose of electroplating and the correct electrode arrangement. In electroplating, the object to be coated is always the negative electrode so that positive metal ions are attracted to it.
(a) Electroplating means coating the surface of one metal with a thin layer of another metal [1] using electrolysis (by passing an electric current). [1]
(b) Two reasons why objects are electroplated (any two): to improve appearance / make it shiny; to prevent corrosion / rusting; to give a harder-wearing surface. [1] each, max [2].
(c) When plating the iron key with nickel, the key is the cathode (the negative electrode) [1], and the other electrode is made of nickel. [1] The positive nickel ions in the solution are attracted to the negative key and are deposited on it, while the nickel anode dissolves to replace them.
Examination reminder: the object being plated is always the cathode; a useful memory aid is that the object gains a coating just as the cathode gains metal from the positive ions.
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