KI eill combine with mercuric iodide `(HgI_(2))` to from `K_(2)HgI_(4)`. The number of solute of solute perticles in solution will decrese. As a result, the depression ion freezing point temperature `(DeltaT_(f))` will decreas and the freezing point of the solution `(T_(f))` will increse.
`2KI+HgI_(2)toK_(2)[HgI_(4)]`
Potassium mercuro-iodide