Question

The metal extracted by leaching with a cyanide is :

• A. Mg
• B. Ag
• C. Cu
• D. Na

Answer 1

Answer: (B)

Ag

Answer 2

Silver ore forms a soluble complex when leached with NaCN solution and from which silver is precipitated using scrap zinc.

Ag2S (conc. ore) + 2NaCN 2AgCN + Na2S.

4Na2S + 5O2 + 2H2O $\longrightarrow$ 2Na2SO4 + 4NaOH + 2S

Na2S is converted in to Na2SO4 . Hence equilibrium shifts towards right side.

AgCN + NaCN $\longrightarrow$ Na[Ag(CN)2] (soluble complex).