1 as a side product in electrolytic refining of copper
2 Parke's process in which \(\mathrm{Zn}\) is used to extract silver by solvent extraction from molten lead
3 by reaction of silver sulphide with \(\mathrm{KCN}\) and then reaction of soluble complex with \(\mathrm{Zn}\)
4 by heating \(\mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN})_{2}\right]\)
Explanation:
Silver is not obtained by heating \(\mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN})_{2}\right]\). It is obtained by treating \(\mathrm{Na}\left[\operatorname{Ag}(\mathrm{CN})_{2}\right]\) with more electropositive metal \(\mathrm{Zn}\), which replaces \(\mathrm{Ag}\) from it.
\(2{\rm{Na}}\left[ {{\rm{Ag}}{{({\rm{CN}})}_2}} \right] + {\rm{Zn}} \to \)
\(\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\rm{N}}{{\rm{a}}_2}\left[ {{\rm{Zn}}{{({\rm{CN}})}_4}} \right] + 2{\rm{Ag}} \downarrow \)
