Question

For gold plating, the electrolyte used is:
(a) \[AuC{l_3}\]
(b) \[HAuC{l_4}\]
(c) \[K[Au{(CN)_2}]\]
(d) None of these

Answer 1

Hint: Electroplating is a technique that involves the plating of a metal onto the surface of another metal. In this process an electric current is used to reduce the dissolved metal cation to produce a thin metal coating on the electrode surface.

Complete Step by Step Answer:
In the electroplating process, the metal which is dissolved at the anode is used for plating a cathode.
In the electroplating process, the salts of noble metal are used. For example., \[{[Au{(CN)_2}]^ - }\] and \[{[Ag{(CN)_2}]^ - }\].

In the case of electroplating of gold (\[Au\]), gold cyanide \[{[Au{(CN)_2}]^ - }\] is used as an electrolyte, and the gold bar acts as an anode. Similarly, for electroplating of silver (\[Ag\]), the metal bar act as an anode, and silver cyanide i.e.,\[{[Ag{(CN)_2}]^ - }\] worked as an electrolyte.

Generally, for electroplating purposes, the sodium and potassium salts are used. For example., \[Na[Au{(CN)_2}]\] and \[K[Au{(CN)_2}]\].
  The above points indicate the\[K[Au{(CN)_2}]\] electrolyte is used for gold (\[Au\]) plating; Therefore, the answer is (c).

Note: The noble metals are the metals that possess higher resistivity to corrosion and these metals are found in nature in their raw materials. For example., Generally the gold (\[Au\]), platinum (\[Pt\]), ruthenium (\[Ru\] ), rhodium (\[Rh\] ), palladium (\[Pd\] ), osmium (\[Os\]), iridium (\[Ir\]), silver (\[Ag\]) are considered as noble metals but sometimes copper (\[Cu\] ) and mercury (\[Hg\]) also counted as noble metals.