Question

Name of the process is cyanide process, in which we add ${\text{Zn}}$ to soluble ${\left[ {{\text{Ag}}{{\left( {{\text{CN}}} \right)}_{\text{2}}}} \right]^ - }$ to get ${\text{Ag}}$. If true enter 1 else 0.

Answer 1

Hint: The cyanide process is used for the extraction of pure silver metal from its ore. Sodium cyanide is used for leaching the roasted ore of silver. And zinc is used to obtain pure silver metal. The metal like silver and gold are not soluble in water and thus, sodium cyanide is used.

Complete step-by-step answer:
We know that the cyanide process is used for the extraction of silver from its ores.
The silver ore is crushed, concentrated and then leached with sodium cyanide $\left( {{\text{NaCN}}} \right)$ solution. The roasted ore of silver is leached using a solution of sodium cyanide.

We know that the process in which the valuable metals are converted to their soluble salts and the impurities remain insoluble is known as leaching. The leaching process of silver metal by sodium cyanide is carried out in the presence of oxygen. The role of sodium cyanide in this process of leaching is to dissolve the silver metal to form a silver cyanide complex. The reaction is as follows:
${\text{4Ag + 8NaCN + 2}}{{\text{H}}_2}{\text{O + }}{{\text{O}}_2}{\text{ }} \to {\text{ 4Na}}\left[ {{\text{Ag}}{{\left( {{\text{CN}}} \right)}_2}} \right]{\text{ + 4NaOH}}$

The pure silver metal can be obtained from the silver cyanide complex by a displacement reaction with zinc metal. The reaction is as follows:
${\text{2Na}}\left[ {{\text{Ag}}{{\left( {{\text{CN}}} \right)}_2}} \right]{\text{ + Zn }} \to {\text{ N}}{{\text{a}}_2}\left[ {{\text{Zn}}{{\left( {{\text{CN}}} \right)}_4}} \right]{\text{ + 2Ag}}$
From the above reaction, we can conclude that ${\left[ {{\text{Ag}}{{\left( {{\text{CN}}} \right)}_{\text{2}}}} \right]^ - }$ combines with ${\text{Zn}}$ and forms $\left[ {{\text{Zn}}{{\left( {{\text{CN}}} \right)}_4}} \right]$ and ${\text{Ag}}$ is obtained in its pure form.
Thus, the role of ${\text{Zn}}$ in the extraction of silver is to obtain pure ${\text{Ag}}$.
Thus, the statement ‘name of the process is cyanide process, in which we add ${\text{Zn}}$ to soluble ${\left[ {{\text{Ag}}{{\left( {{\text{CN}}} \right)}_{\text{2}}}} \right]^ - }$ to get ${\text{Ag}}$’ is true hence, 1.

Note: The most common ore of silver is argentite or silver glance. Potassium cyanide can also be used to dissolve the silver metal instead of sodium cyanide. The process is mainly used for the extraction of valuable metals like gold and silver.