Gradual addition of potassium iodide solution to aqueous B i N O 3 3 solution initially produces a dark brown precipitate which dissolves in excess of KI to give a clear yellow solution. Identify the yellow precipitate.

Step-by-step solution

At first B i N O 3 3 undergoes hydrolysis. Nitric acid is formed which oxidises I − to iodine. The liberated iodine dissolves in K to form yellow precipitate of KI 3 . B i N O 3 3 + H 2 O → B i O H N O 3 2 + H N O 3 2 H N O 3 → H 2 O + 2 N O 2 + O 2 K I + H 2 O + O → 2 K O H + I 2 D a r k b r o w n I 2 + K I → K I 3 y e l l o w s o l u t i o n