Question

The freezing point (in `.^(@)C)` of a solution containing `0.1g` of `K_(3)[Fe(CN)_(6)]` (Mol. wt. `329`) in `100 g` of water `(K_(f) = 1.86 K kg mol^(-1))` is :
A. `-2.3 xx 10^(-2)`
B. `-5.7 xx 10^(-2)`
C. ( c) `-5.7 xx 10^(-3)`
D. `-1.2 xx 10^(-2)`

Answer 1

Correct Answer - A
`K_(3)[Fe(CN)_(6)] rarr 3K^(+) + [Fe(CN)_(6)]^(3-)`
`i=4`
`Delta T_(f) = K_(f) xx i xx (w)/(m) xx (1000)/(W_("in g"))`
`= 1.86 xx 4 xx (0.1)/(329) xx (1000)/(100) = 2.3 xx 10^(-2)`
`T_(f) = -2.3 xx 10^(-2)`