calculate i and the apparent dissociation of CsCL in this solution?

Question

CsCL dissolves in water according to
CsCL(s)===>Cs(aq)+CL(aq)
A 0.121m solution of CsCL freezes at -0.403C calculate i and the apparent dissociation of CsCL in this solution

Answer 1

the cryoscopic constant of water is -1.858
so -0.403/-1.858=2.169
if CsCl was not dissociated the freezing depression would be
-0.121*1.85 =-2.239
so i=0.403/0.2239=1.8

and you have i = 1+D (degree dissociation)*(p-1)
where p =2 as there are 2ions
so 1.8 =1+(2-1)*D=1+D

D=0.8 4molecules out of 5 are dissociated