Question

The electrolytes usually used in the electroplating of gold and silver, respectively, are
1. [Au(OH)₄]^- and [Ag(OH)₂]^-
2. [Au(NH₃)₂]⁺ and[Ag(CN)₂]^-
3. [Au(CN)₂]^- and [Ag(CN)₂]^-
4. [Au(CN)₂]^- and [AgCl₂]^-

Answer 1

Correct Answer - Option 3 : [Au(CN)₂]^- and [Ag(CN)₂]^-

Concept:

Electroplating is a process of coating one metal or metal object with a very thin layer of another metal typically applying a direct electric current. Electrolytes used in the electroplating of gold and silver are given in the table below:

Process	Article to be plated out Acts as cathode	Pure metal block acts an anode by which electroplating will be done	Electrolyte (aqueous solution)
a) Gold plating	Article	Au(s)	Na[Au(CN)2] (sodium auro-cyanide)
b) Silver plating	Article	Ag(s)	Na[Ag(CN)2] (sodium argento-cyanide)