What frezing point depression would be predicted for `0.2`molal solution of benzoic acid in benzene if latent heat of fusion is `40.00cal g^(-1)` at (freezing point)for benzene ?(assume no change in molecular state)

Options

A. `0.52^(@)`
B. `5.2^(@)`
C. `0.0052^(@)`
D. `0.78^(@)`

Answer

D

Explanation

`T_(0)`=freezing point of solvent
`DeltaH_(f)`=Latent heat of fusion
`k_(f)=(RT_(0)^(2))/(1000cancelOH_(f))=(2xx(280^(2)))/(1000xx40)=(156800)/(40000)=3.92kmol^(-1)kg`
`DeltaT_(f)= "molarity" xxk_(f)=0.2xx3.92=0.78^(@)`