Solutions Question 172
Question: How many grams of methyl alcohol should be added to 10 litre tank of water to prevent its freezing at 268K ? ( $ K_{f} $ for water is $ 1.86Kkgmo{l^{-1}} $ )
Options:
A) 880.07 g
B) 899.04 g
C) 886.02 g
D) 868.06 g
Show Answer
Answer:
Correct Answer: D
Solution:
$ \Delta T_{f}=K_{f}m $ where w=molality $ 273-268=1.86\times \frac{w}{M\times v} $
$ 5=1.86\times \frac{w}{32\times 10} $
$ w=\frac{5\times 32\times 10}{1.86} $
$ =860.2\approx 868.06g $
BETA
