General Principles and processes of Isolation of Elements
medium

There are following extraction process of silver but not

A

as a side product in electrolytic refining of copper

B

Parke's process in which $Zn$ is used to extract silver by solvent extraction from molten lead

C

by reaction of silver sulphide with $KCN$ and then reaction of soluble complex with $Zn$

D

by heating $Na[Ag(CN)_2)$

Solution

The Parkes process is a process for removing silver from lead.

Electrolytic process gives the highest-purity metal product as well as the best recovery of valuable impurities. It is used for copper, nickel, lead, gold, and silver.

Reactions occurs in extraction of silver-

$Ag _2 S +4 NaCN \rightarrow 2 Na \left[ Ag ( CN )_2\right]+ Na _2 S$ (reversible reaction)

$2 Na \left[ Ag ( CN )_2\right]+ Zn \rightarrow Na _2\left[ Zn ( CN )_4\right]+2 Ag$

here we can also use $K$ instead of $Na$.

But by heating of $Na \left[ Ag ( CN )_2\right], Ag$ is not produced as on and heating

$Na \left[ Ag ( CN )_2\right]$ forms a complex product of $Ag$ and not simple $Ag$.

Hence option $D$ is correct.

Standard 12
Chemistry

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