When `1.22 g C_(6)H_(5)COOH` is added into two solvents, the following data of `DeltaT_(b)` and `K_(b)` are obtained:
i. In `100 g CH_(3)COCH_(3)`,`DeltaT_(b)=0.17`,`K_(b)=1.7 kg K mol^(-1)`.
ii. In `100 g` benzene,`DeltaT_(b)=0.13` and `K_(b)=2.6 kg K mol^(-1)`.
Find out the molecular weight of `C_(6)H_(5)COOH` in both cases and interpret the results.

Explanation

(a) `DeltaT=K_(b)xx(w_(B)xx1000)/(m_(B)xxw_(A))`
`0.17=1.7xx(1.22xx1000)/(m_(B)xx100)`
`m_(B)=122` (normal molecular mass of benzoic acid)
(b) `DeltaT=(K_(b)xxw_(B)xx1000)/(m_(B)xxw_(A))`
`0.13=(2.6xx1.22xx1000)/(m_(B)xx100)`
`m_(B)=244`
(Abnormally double molecular mass of benzoic acid, it shows association of benzoic acid in benzene).