a std soln of I2in water contains 0.33 g of I2 in one litre flask.more than this dissolve in a KI soln bcoz of the foll. equil.
I
2+I
-
I
3- A 0.1M KI soln. actually dissolves 12.5g of iodine per litre most of which is converted to I3- Assuming tat conc of I2 in all saturated soln. is same,calc K for d above reacn.