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 produce nitric acid.`HNO_(3)` oxidises `KI` i.e., `I_(2)` (brown ppt.) is formed . The precipitate which dissolves in excess of `KI` and forms a yellow coloured solution of `Kl_(3)`
`Bi(NO_3)_(3)+H_(2) to Bi(OH)(NO_3)_(2)+HNO_(3)`
`6KI+8HNO_(3) rarr 6KNO_(3)+2NO+underset("Brown ppt")(3I_(2))+4H_(2)O`
`KI+I_(2) rarr underset("Yellow soin")(KL_(3))`.