MetallurgyHard
Question
Extraction of silver from Ag2S by the use of sodium cyanide is an example of :
Options
A.roasting
B.hydrometallurgy
C.electrometallurgy
D.smelting
Solution
Ag2S (concentrated ore) + 2NaCN (aq) 
2AgCN (s) + Na2S (aq).
4Na2S (aq) + 5O2 (g) + 2H2O (l) → 2Na2SO4 (aq) + 4NaOH (aq) + 2S (s)
AgCN (s) + NaCN (aq) → Na[Ag(CN)2] (soluble complex)
2Na[Ag(CN)2] (aq) + Zn (dust) → 2Ag (s) + Na2[Zn(CN)4] (aq). Hence these reactions suggest that extraction of silver from Ag2S by the use of sodium cyanide is an example of hydrometallurgy.
2AgCN (s) + Na2S (aq).4Na2S (aq) + 5O2 (g) + 2H2O (l) → 2Na2SO4 (aq) + 4NaOH (aq) + 2S (s)
AgCN (s) + NaCN (aq) → Na[Ag(CN)2] (soluble complex)
2Na[Ag(CN)2] (aq) + Zn (dust) → 2Ag (s) + Na2[Zn(CN)4] (aq). Hence these reactions suggest that extraction of silver from Ag2S by the use of sodium cyanide is an example of hydrometallurgy.
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