General Principles and Processes of Isolation of Elements - Result Question 8

####8. Extraction of gold and silver involves leaching with CNion. Silver is later recovered by [2017]

(a) distillation

(b) zone refining

(c) displacement with Zn

(d) liquation

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Solution:

  1. (c) Zn being more reactive than Ag and Au, displaces them.

4Ag+8NaCN+2H2O+O2 Leaching 4Na[Ag(CN)2]+4NaOH

Soluble Sodium dicyanoargentate (I)

Soluble cyanide compound can be treated with Zn to give metal by displacement.

2Na[Ag(CN)2]+ZnNa2[Zn(CN)4+2Ag] Displacement 



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