0.5 molal aqueous solution of a weak acid ( HX ) is 20 % . ionised. If K _ f of water is 1.86 ~K ~kg ~mol ⁻¹ , the lowering in freezing point of solution is

Step-by-step solution

HX H ⁺+ X ⁻ For dissociation of an electrolyte, = i-1 n-1 0.2= i-1 2-1 i -1=0.2 i =0.2+1=1.2 Now, T _ f = i k _ f m =1.2 1.86 0.5=1.12 ~K