Question

Insulin is dissolved in suitable solvent and the osmotic pressure $\left(\pi \right)$ of solutions of various concentrations $\left(g/c{m}^3\right)$ C is measured at ${27}^{0}C$.The slope is plot of $\pi$ against C is found to be $4.1\times {10}^{-3}$.the molecular mass of insulin is?

Answer 1

Expression for osmotic pressure $\pi =CRT$.

$\pi =\frac{1000RT}{M}$

when a graph of the osmotic pressure vs concentration (g/cc) is plotted. The slope is $\frac{1000RT}{M}$

$\Rightarrow 4.65x{10}^{-3}=\frac{\left(0.0821\right)\left(293\right)\left(1000\right)}{M}$

$\Rightarrow M=5.26x{10}^{6}g/mol$

Molecular mass of insulin $=5.26x{10}^{6}g/mol$