Question

At 300 K, 36 g of glucose present per litre in its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of a urea solution is 1.52 bar its at the same temperature, concentration is

• A. 1.6 M
• B. 0.61 M
• C. 0.061 M
• D. None of these

Answer 1

Answer: (C)

0.061 M

Answer 2

$\pi_1 V = n_1 RT$
$\pi_2 V = n_2RT$
$\frac{\pi_1}{\pi_2} = \frac{n_1}{n_2}$

$n_1=\frac {36}{180}=\frac 15$ mol
$\pi_1$ = 4.98 bar
$\pi_2$ = 1.52 bar
$\frac{4.98}{1.52} = \frac{\frac 15}{n_2}$

$n_2 = \frac{1.52}{4.98 \times 5}$ = 0.061 M
Osmotic pressure is a colligative property

$\therefore$ 0.061 M Glucose = 0.061 M urea