Question

Native silver metal forms a water soluble complex with a dilute aqueous solution of NaCN in the presence of(a) nitrogen (b) oxygen (c) carbon dioxide (d) argon

Answer 1

(B)

Ag dissociates in a solution of NaCN in the presence of air, and forms sodium argentocyanide.

Answer 2

Answer:

B) Oxygen

Explanation:

A water soluble complex of silver with a dilute aqueous solution of NaCN is known as sodium argentocyanide. In the cyanide process, the native form is first crushed and is then treated with 0.142% solution of NaCN and then aerated. The equation so formed is -

= 4Ag + 8NacN + 2H20 + O2 → 4Na [ Ag(Cn)2] + 4NaOH

Argentocyanide is a soluble element. Further, the metal is recovered from the complex by overall reduction with the zinc. Thus, native silver metal forms a water soluble complex with a dilute aqueous solution of NaCN in the presence of oxygen.