Question

A 0.10 M solution of a mono protic acid (`d=1.01g//cm^(3)`) is 5% dissociated what is the freezing point of the solution the molar mass of the acid is 300 and `K_(f)(H_(2)O)=1.86C//m`
A. `-0.189^(@)C`
B. `-0.194^(@)C`
C. `-0.199^(@)C`
D. none

Answer 1

Correct Answer - C
Mass of 1 litre of solution =1010 gram
mass of solvent =1010 `-300xx0.1=980` gram
`m=(0.1)/(0.98)=0.102`
`DeltaT_(f)=iK_(f)m=(1+alpha)K_(f)m`
`impliesDeltaT_(f)=0.199^(@)C`
`impliesT_(f)=0-0.199^(@)C=-0.199^(@)C`