Discussion Forum



1)

In the cyanide extraction process of silver from argentite ore' the oxidizing and reducing agents used are


A) $O_{2}$ and CO respectively

B) $O_{2}$ and Zn dust respectively

C) $HNO_{3}$ Zn dust respectively

D) $HNO_{3}$ and CO respectively

Answer:

Option B

Explanation:

The reactions involved in the extraction of silver by the cyanide process are

   $Ag_{2}S+CN^{-}+O_{2}  \rightarrow   [Ag(CN)_{2}]^{-}+SO_{2}$ ..................(i)

$[Ag(CN)_{2}]^{-}+Zn \rightarrow [Zn(CN)_{4}]^{2-}$+Ag ..........(ii)

In reaction (i), sulphide is oxidized to SO2 by oxygen. In the reaction (ii),

Silver ion ($Ag^{+}$) is reduced to Ag by Zn.

Therefore,  $O_{2}$ . is oxidisinS agent and Zn is reducing agent.