The freezing point of 0.2 molal K2SO4 is −1.1oC. Calculate percentage degree of dissociation of K2SO4. Kf for water is 1.86o

ΔTf=freezing point of water - freezing point of solution =0oC−(−1.1oC)=1.1oWe know that, ΔTf=i×Kf×m1.1=i×1.86×0.2∴ i=1.11.86×0.2=2.95But we know i=1+(n−1)α2.95=1+(3−1)α=1+2αα=0.975Percentage degree of dissociation = 97.5