Question

5 % Solution of cane sugar (m.wt. 342) is isotonic with 0.877 % solution of urea. What is the molecular weight of urea? *

Answer 1

Answer:

ANSWER

When two solutions are isotonic, they have equal osmotic pressures.

But osmotic pressure is directly proportional to the concentration. Hence, the two solutions have equal value of concentrations.

Hence,

molar mass of cane sugar

mass of cane sugar

=

molar mass of urea

mass of urea

.

Hence,

342

5

=

molar mass of urea

0.877

.

Hence, the molar mass of urea is 60 g/mol.