Question

The freezing point of pure chloroform is -63.5°C, and its freezing point depression constant is 4.07°C•kg/mol. If the freezing point of a solution of benzoic acid in chloroform is -70.55°C, what is the molality of this solution? 0.58 m 1.7 m 16 m 17 m

Answer 1

Answer: The molality of this solution is 1.7 m

Step-by-step explanation:

Depression in freezing point:

`T_f^0-T^f=i* k_f* m`

where,

`T_f` = freezing point of solution =
`-70.55^0C`

`T_f^0` = freezing point of pure chloroform =
`-63.5^0C`

`k_f` = freezing point constant of benzene =
`4.07^0Ckg/mol`

m = molality

i = Van't Hoff factor = 1 (for non-electrolyte)

`-63.5-(-70.55)^0C=1* 4.07^0Ckg/mol* m`

`7.05=1* 4.07^0Ckg/mol* m`

`m=1.7`

Thus the molality of this solution is 1.7 m