Write the equation for the extraction of silver by leaching with sodium cyanide and show that the leaching proces is a redox reaction.

Explanation

The crushed ore of argentite `(Ag_(2)S)` is leached with sodium cyanide solution.This reaction froms sodium argento cyanide Na `[Ag(CN)_(2)]`.
Step1. `Ag_(2)S+4NaCN hArr2Na[Ag(CN)_(2)]+Na_(2)S`
The solution of sodium argento cyanide combines with zinc dust and forms sodium tetra cyano zincate and precipitated silver.
Step2:`Zn+2Na[Ag(CN)_(2)]toNa2[Zn(CN)_(4)]+2Ag darr`
In the step2,redox reaction take place.
` (0)" "(2+)`
`Zn " " to " "Zn` (Oxidation)
`(+1)" "(0)`
`Ag " to "Ag(reduction)`.