Question

Explain osmotic pressure and establish an expression for finding the molar mass of solute with the help of this.

Hint:

Osmotic pressure is a colligative property used to determine the molar mass of large biomolecules.

Answer 1

Step 1: Definition of Osmotic Pressure Osmotic pressure (\(\pi\)) is the pressure required to stop the flow of solvent molecules through a semipermeable membrane. Step 2: Van't Hoff Equation for Osmotic Pressure \[ \pi = CRT \] where:
- \( C \) = Concentration of solute (mol L\(^{-1}\))
- \( R \) = Universal gas constant
- \( T \) = Temperature (Kelvin) Step 3: Finding Molar Mass of Solute Since concentration (\( C \)) is given by \( C = \frac{n}{V} \) and \( n = \frac{w}{M} \), we substitute: \[ \pi V = \frac{wRT}{M} \] Rearranging for molar mass \( M \): \[ M = \frac{wRT}{\pi V} \]