Chemistry · Importance of coordination compounds (in qualitative analysis, extraction of metals and in biological systems)
Extraction of gold and silver involves leaching the metal with ion. The metal is
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 metal complex
- C. calcination followed by roasting
- D. thermal decomposition of metal complex
Step-by-step solution
In the cyanide process, gold and silver form soluble complexes like [Au(CN)2]− and [Ag(CN)2]−. These are treated with a more reactive metal, typically zinc, which displaces the precious metal from the complex through a redox reaction: 2[Au(CN)2]− + Zn → [Zn(CN)4]2− + 2Au. Roasting, calcination, or thermal decomposition are not used for recovery from cyanide complexes.
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