Question

What is the role of zinc metal in the extraction of silver? [AI 2015 Ajmer; AI 2014]

Answer 1

Answer:

During extraction of silver, the finely powdered silver ore is treated with dilute KCN solution to form a cyano complex of silver. This complex is water soluble. Then zinc is added to the solution. More electropositive zinc displaces silver from the complex.

Explanation:

Answer 2

Answer:

During extraction of silver, the finely powdered silver ore is treated with dilute KCN solution to form a cyano complex of silver. This complex is water soluble.

Ag2 S + 4NaCN ⇌ 2Na[Ag(CN)2 ] + Na2 S

Then zinc is added to the solution. More electropositive zinc displaces silver from the complex.

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