(CuSO\_4 ) when reacts with KCN forms CuCN which is insolubl... | Chemistry | SolveeIt

Question

$CuSO_4$ when reacts with KCN forms CuCN which is insoluble in water. It is soluble in excess of KCN due to the formation of the complex :-

$K_2[Cu(CN)_4]$

$K_3[Cu(CN)_4]$

$Cu(CN)_2$

$Cu[KCu(CN)_4]$

Answer

$K_3[Cu(CN)_4]$

Explanation

Solution

$CuSO_4$ reacts with KCN to give a white precipitate of cuprous cyanide and cyanogen gas.
The cuprous cyanide dissolves in excess of KCN forming $K_3[Cu(CN)_4]$
$CuSO_4+2KCN \rightarrow K_2SO_4+Cu(CN)_2$
$\hspace57mm Unstable$
$2Cu(CN)_2 \rightarrow 2CuCN+CN-CN$
$\hspace30mm Insoluble\, \, cyanogen$
$CuCN+3KCN \rightarrow K_3[Cu(CN)_4]$
$\hspace45mm Soluble$

Chemistry Question on coordination compounds

Solution