Question

Extraction of gold and silver involves leaching the metal with $C{N}^{-}$ ion. The metal is recovered by:

• A. Displacement of metal by some other metal from the complex ion
• B. Roasting of the metal complex
• C. Calcination followed by roasting
• D. Thermal decomposition of metal complex

Answer 1

The correct option is A Displacement of metal by some other metal from the complex ion

$2\left[Ag\right(CN{)}_2{]}^{-}+Zn\to 2Ag+\left[Zn\right(CN{)}_4{]}^{2-}$
or, $2\left[Au\right(CN{)}_2{]}^{-}+Zn\to 2Au+\left[Zn\right(CN{)}_4{]}^{2-}$