Question

In blue solution of copper sulphate excess of `KCN` is added then solution becomes colourless due to the formation of :
A. `[Cu(CN)_(4)]^(2-)`
B. `Cu^(2+)` get reduced to form `[Cu(CN)_(4)]^(3-)`
C. `Cu(CN)_(2)`
D. `CuCN`

Answer 1

Correct Answer - B
`Cu^(2+)+6CN^(-) to [Cu^(+)(CN)_(4)]^(3-)+(CN)_(2)`
`Cu^(2+)+2CN^(-) to Cu(CN)_(2)darr("yellow"), 2Cu(CN)_(2)darr ("white")+(CN)_(2) darr`
`CuCN darr +CN^(-) to [Cu^(I)(CN)_(4)]^(3-)` (colourless soluble complex)