Question

Gradual addition of `KI` solution to `Bi(NO_3)_(3)` solution initially produces a dark brown precipitate which dissolves in excess of `KI` to give a clear yellow solution. Write chemical equation for the above reactions.

Answer 1

`Bi(NO_(3))_(3)` undergoes hydrolysis to give `HNO_(3)` (oxidising agent) which liberates `l_(2)` (dark brown ppt) from Kl solution, iodine `(I_(2))` dissolves in excess of `Kl` to give `KI_(3)` (yellow solution)
(a) `Bi(NO_(3))_(3)+H_(2)Oto[Bi(OH)(NO_(3))_(2)]+HNO_(3)`
(b) `6I^(-)+2NO_(3)^(-)+8H^(+)to2NO_(2)+4H_(2)O+3I_(2)`
(c) `KI+I_(2) to KI_(3) ` (Yellow solution).