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What is the Role of Zinc Metal in the Extraction of Silver ? - CBSE (Science) Class 12 - Chemistry

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Question

What is the role of zinc metal in the extraction of silver ?

Solution

Silver is extracted from the ore-argentite (Ag2S). This process of extraction of silver is called as cyanide process as sodium cyanide solution is used. The ore is crushed, concentrated and then treated with sodium cyanide solution. This reaction results into sodium argento cyanide Na[Ag(CN)2]. The reaction is as follows:

AgS + 4NaCN ⇌ 2Na[Ag(CN)2] + Na2S

The solution of sodium argento cyanide combines with zinc dust. It forms sodium tetra cyanozicate and precipitates silver. This precipitated silver is called as spongy silver. The reaction is as follows:

Zn + 2Na[Ag(CN)2] → Na2[Zn(CN)4] + 2Ag

The spongy silver is fused with potassium nitrate to get pure silver. This silver obtained is purified by electrolytic process.

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Solution What is the Role of Zinc Metal in the Extraction of Silver ? Concept: Oxidation Reduction.
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