Answer: The approximate molecular mass of the polypeptide is 856 g/mol
Explanation:
To calculate the concentration of solute, we use the equation for osmotic pressure, which is:
[tex]\pi=iMRT[/tex]
Or,
[tex]\pi=i\times \frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution in L)}}\times RT[/tex]
where,
[tex]\pi[/tex] = osmotic pressure of the solution = 4.19 torr
i = Van't hoff factor = 1 (for non-electrolytes)
Mass of solute (polypeptide) = 0.327 g
Volume of solution = 1.70 L
R = Gas constant = [tex]62.364\text{ L.torr }mol^{-1}K^{-1}[/tex]
T = temperature of the solution = [tex]26^oC=[273+26]K=299K[/tex]
Putting values in above equation, we get:
[tex]4.19torr=1\times \frac{0.327}{\text{Molar mass of solute}\times 1.70}\times 62.364\text{ L.mmHg }mol^{-1}K^{-1}\times 299K\\\\\text{molar mass of solute}=856g/mol[/tex]
Hence, the molar mass of the polypeptide is 856 g/mol
