Question on Freezing Point

What will be the freezing point of an 1 molal Sulphuric Acid solution if K_f of water is 1.8 K.Kg/mol?

Answer:

The depression in freezing point DT_f = i * K_f * m where “i” is the number of particles present in the solution for every particle dissolved and “m” is the molality of the solution. One mole of Sulphuric acid will dissociate to give two moles of H⁺ and one mole of SO₄^2- ions.

DT_f = i * K_f * m = 3 * 1.86 * 1 = 5.58

So, the freezing point of the solution will be, 0 - 5.58 = -5.58°C