Answer: The molar mass of unknown solute is 195.44 g/mol.
Explanation:
To calculate the concentration of solute, we use the equation for osmotic pressure, which is:
[tex]\pi=icRT[/tex]
where,
[tex]\pi[/tex] = osmotic pressure of the solution = 0.750 atm
i = Van't hoff factor = 1 (for non-electrolytes)
c = concentration of solute = ?
R = Gas constant = [tex]0.0820\text{ L atm }mol^{-1}K^{-1}[/tex]
T = temperature of the solution = [tex]25^oC=[273+25]=298K[/tex]
Putting values in above equation, we get:
[tex]0.750atm=1\times c\times 0.0820\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\c=0.0307mol/L[/tex]
The concentration of solute is 0.0307 mol/L
This means that, 0.0307 moles are present in 1 L of solution.
To calculate the molecular mass of solute, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Moles of solute = 0.0307 mol
Given mass of solute = 6g
Putting values in above equation, we get:
[tex]0.0307mol=\frac{6g}{\text{Molar mass of solute}}\\\\\text{Molar mass of solute}=195.44g/mol[/tex]
Hence, the molar mass of unknown solute is 195.44 g/mol.
