Chemistry - Metallurgy Question with Solution | TestHub

The cyanide process (MacArthur-Forrest process) for silver extraction involves leaching silver ore with a dilute sodium cyanide solution in the presence of air. Silver sulfide reacts with sodium cyanide to form a soluble dicyanoargentate(I) complex.

The reaction is:

$${\mathrm{Ag}}_2\mathrm{S}(s)+4\mathrm{NaCN}(aq)⟶2\mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN}{)}_2\right](aq)+{\mathrm{Na}}_2\mathrm{S}(aq)$$

This corresponds to option 3, with a slight correction to the stoichiometry of the product complex. The correct complex formed is $\mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN}{)}_2\right]$.