What is osmotic pressure and how is it related with the molecular mass of a non-volatile substance? What advantage the osmotic pressure method has over the elevation of boiling point method for determining molecular masses?

Explanation

For definition of osmotic pressure, refer to Section 2.10.4. `piV=nRT`
`pi=(n)/(V)RT=(W_(B)xxRxxT)/(Mw_(B)xxV)`
`Mw_(B)=(W_(B)xxRxxT)/(pixxV)` ,
where `Mw_(B)` is the molar mass of the solute.
The advantage of the osmotic pressure method is that it is measured at room temperature. It is convenient to measure at room temperature then at boiling point. The value of osmotic pressure is quite appreciable even for very dilute solutions of polymers as compared to that of elevation boiling point.