Iodine is sparingly soluble in pure water. However, it does `dissolve' in solutions containing excess iodide ion because of the following reaction:

I-(aq) + I2(aq)= I3-(aq) K = 710.
For each of the following cases calculate the equilibrium ratio of [I3-] to [I2].

6.00×10-2 mol of I2 is added to 1.00 L of 6.00×10-1 M KI solution.