Question

The osmotic pressure of a solution of an organic substance containing $18g$ in one litre of solution at $293K$ is $2.414\times {10}^{5}N{m}^{-2}$. Find the molecular mass of the substance if $S=8.3J{K}^{-1}$ per mol

• A. $181.33$
• B. $173.33$
• C. $160.33$
• D. $152.33$

Answer 1

The correct option is A $181.33$

Applying the equation,

$PV=\frac{w}{m}\cdot \text{RT}\text{or}m=\frac{w}{PV}\cdot \text{RT}\text{Given,}P=2.414N{m}^{-2},V=1.0\text{lit}=1\times {10}^{-3}{m}^3,R=8.3{\text{JK}}^{-1}\text{per mol,}w=18\text{g and}T=293\text{K}$
$m=\frac{18}{2.414\times {10}^5\times 1\times {10}^{-3}}\times 8.3\times 293=181.33g$