question_answer

Zinc and not copper is used for the recovery of silver from the complex \[{{[Ag{{(CN)}_{2}}]}^{-}}\]. Discuss.

Answer:

                Zinc is a very powerful reducing agent and readily displaces silver present in the complex. \[Zn+2\,{{[Ag\,{{(CN)}_{2}}]}^{-}}\xrightarrow{\,}\,\underset{\text{Soluble}}{\mathop{{{[Zn{{(CN)}_{4}}]}^{2-}}}}\,+\underset{\text{(ppt}\text{.)}}{\mathop{2Ag}}\,\] No doubt copper is also more reducing than silver but is not so effective as zinc. Moreover, zinc is cheaper than copper.