A 5.25% solution of a substance is isotonic with a 1.5% solution of urea ( molar mass = 60 g mol -1 ) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g cm -3

Question

A 5.25% solution of a substance is isotonic with a 1.5% solution of urea ( molar mass = 60 g mol -1 ) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g cm -3 , molar mass of the substance will be

TestHub · Accepted Answer

Isotonic solutions have same osmotic pressure.

$π_{1} = C_{1} {RT, π}_{2} = C_{2} RT$

For isotonic solution, $π_{1} = π_{2}$

$π = (\frac{5 \cdot 25 / M}{100} \times 10) RT = (\frac{1 \cdot 5 / 60}{100} \times 10) RT$

$\frac{5 \cdot 25}{M} = \frac{1 \cdot 5}{60}$

$M = \frac{60 \times 5 \cdot 25}{1 \cdot 5} = 210 g / mole$

Chemistry - Liquid Solution Question with Solution | TestHub

Options:

Doubts & Discussion