IIT JEE , AIEEE Forum - Chemistry , Inorganic Chemistry

priyamuthu

A: No special reagents needs to be added to prevent the reverse reations during leaching of silver glance by NaCN .
R:O2 in air converts Na2S to Na2SO4 thereby removing the by product formed

dev_22oct

REAGENT IS ADDED TO PREVENT THE REVERSE REACTION

the modern cynide process is based on the property of silver ore to pass into the solution with alkali cynides and ppt of ag from solution by adding zn.

Ag₂S + 4NaCN-----> 2Na[Ag(Cn)₂] + Na₂S

the sulphide formed is converted to thiosulphate and sulphate and thus prevent back ward reaction.

2NaS + 2O₂ +H₂O----->Na₂S₂O₃+ 2NaOH

Na₂S₂O₃+2NaOH+2O₂--->2Na₂SO₄+H₂O

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