Question

Extraction of silver is done mainly from argentite (Ag₂S) ore.

The concentrated ore on treatment with dil. NaCN solution and then followed by continuous agitation for several hours, which of the following products are obtained?

Options

• AgCN and Na₂S

• Ag and NaCN

• Na₂SO₄ and Na₂SO₃

• Na[Ag(CN)₂] and Na₂S

Answer 1

AgCN and Na₂S

Explanation:

In the MacArthur-Forrest cyanide process, the concentrated argentite ore (Ag₂S) is treated with dilute NaCN and agitated with air. This causes silver to form a soluble complex, sodium dicyanoargentate (I):

\[\ce{Ag2S + 4NaCN -> 2Na[Ag(CN)2] + Na2S}\]

Na[Ag(CN)₂] is the soluble complex formed. Na₂S is the by-product formed in the reaction.