Question

The freezing point of aqueous solution that contains `5%` by mass urea. `1.0%` by mass `KCl` and `10%` by mass of glucose is:
`(K_(f) H_(2)O = 1.86 K "molality"^(-1))`
A. (a) `290.2 K`
B. (b) `285.5 K`
C. ( c) `269.93 K`
D. (d) `250 K`

Answer 1

Correct Answer - C
` Delta T = Delta T` for glucose `+ Delta T` for `KCl+Delta T` for urea
`= (1000 xx 1.86 xx 10)/(100 xx 180) + (1000 xx 1.86 xx 1 xx 2)/(74.5 xx 100) + (1000 xx 1.86 xx 5)/(100 xx 60) = 3.069`
`:. f.pt = 273 - 3.069 = 269.93 K`