Question

1) In metallurgy of Ag and Au with NaCN,
is used as an oxidising agent.
(Chp.6)
(a) Air (O) (b) KNO, (c) Zn (d) H2O2​

Answer 1

Air(0)

Explanation:

• In  extraction of Ag (gold) and  Au (silver)  the metal is subjected to leaching with NaCN and KCN

• The given equation will be - 4M+8CN⁻+ 2H₂O +O₂⇒ 4[M(CN)₂] + 4OH⁻
• It is a type of oxidation reaction

• The compound formed is reacted with zinc which forms the metal.

• 4[M(CN₂)]⁻+Zn→ [Zn (CN)₄]⁻²+ 2M
• M represents silver or gold metal.