Extraction of gold and silver involes leaching with $CN^-$ ion. Silver is later recovered by :-
- distillation
- zone refining
- displacement with Zn
- liquation
The Correct Option is C
Solution and Explanation
From Native ore,
$4 Ag +8 NaCN +2 H _{2} O + O _{2} \stackrel{\text { Leaching }}{\longrightarrow} \underset{\text{Soluble Sodium dicyanoargentate(I)}}{4Na [Ag(CN)_2]} + 4 Na OH$
$2 Na \left[ Ag ( CN )_{2}\right]+ Zn \stackrel{\text { Displacement }}{\longrightarrow} Na _{2}\left[ Zn ( CN )_{4}\right]+2 Ag \downarrow$
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Concepts Used:
General Principles and Processes of Isolation of Elements
What are Ores and Minerals?
Minerals are the naturally occurring, homogeneous inorganic solid substances. They are having a definite chemical composition and crystalline structure, hardness and color. For example, copper pyrite, calamine, etc.
Impurities in an ore are called gauge. The removal of a gauge from the ore is called concentration ore.
Several steps are involved in the extraction of pure metal from ores. Major steps are as follows –
- Concentration of the ore
- Isolation of the metal from its concentrated ore
- Purification of the metal