Question

Copper sulphate when dissolved in excess of kcn gives

Answer 1

Copper sulphate when react with KCN first give

precipitate of cupric cyanide which reduce into

Cu2CN2 and dissolve in excess of KCN to give

soluble K3[Cu(CN)4] complex salt

[CuSO4+2KCN→Cu(CN)2+K2SO4|×2 Cupriccyanide

2Cu(CN)2→Cu2(CN)2+NC−CN Cyanogen

Cu2(CN)2+6KCN→2K3[Cu(CN)4] Soluble complex salt 2CuSO4+10KCN→2K3[Cu(CN)4]+2K2SO4+(CN)2