Question

A solution contains non-volatile solute of molecular mass $M_{p}$. Which of the following can be used to calculate molecular mass of the solute in terms of osmotic pressure (m = Mass of solute, V = Volume of solution and π = Osmotic pressure).

• A. $Mp = \left( \frac{m}{\pi} \right)VRT$
• B. $Mp = \left( \frac{m}{V} \right)\frac{RT}{\pi}$
• C. $Mp = \left( \frac{m}{V} \right)\frac{\pi}{RT}$
• D. $Mp = \left( \frac{m}{V} \right)\pi RT$

Answer 1

Answer: (B)

$Mp = \left( \frac{m}{V} \right)\frac{RT}{\pi}$

Answer 2

$\pi = \frac{n}{V}RT \Rightarrow M_{P} = \left( \frac{m}{V} \right)\frac{RT}{\pi}$