Question

Insulin is dissolved in a suitable solvent and the osmotic pressure $\pi$ of solution of various concentrations$\left(g/c{m}^{-3}\right)$ C is measured at $\text{2}{\text{0}}^{\text{o}}$ . The slope of a plot of $\pi$ against c is found to be $4.65\times {10}^{-3}$. The molecular weight of the insulin(g/mol) is :

• A. $3\times {10}^5$
• B. $9\times {10}^5$
• C. $4.5\times {10}^5$
• D. $5.16\times {10}^6$

Answer 1

The correct option is D $5.16\times {10}^6$

$\pi =\frac{W}{M}\times \frac{RT}{V}or\frac{\pi }{C}=\frac{RT}{M}$
$\therefore slope=\frac{RT}{M}$

or $M=\frac{0.082\times 293}{4.65\times {10}^{-3}\times {10}^{-3}}$

$\Rightarrow 5.16\times {10}^{6}g$