Question

A solution of glycerine with a concentration of 10.2 gm/ lit. and 2% solution of glucose are isotonic. Determine the molecular weight of glycerine. (Molecular weight of glucose = 180)

Answer 1

For glucose solution ${\pi }_{A}V=mRT⟶\left(1\right)$

${\pi }_A\times 0.1=\left(\frac{2}{180}\right)RT$

For glycerin solution= ${\pi }_{B}V=nRT⟶\left(2\right)$

$\Rightarrow {\pi }_B\left(1L\right)=\left(\frac{10.2}{M_B}\right)\times R\times T$

$\Rightarrow {\pi }_A={\pi }_B$

$\Rightarrow \frac{1}{180}\times \frac{RT}{0.1}=\frac{10.2}{M_B}\frac{RT}{1}$

$\Rightarrow M_B=91.8g/mol$