Question

Define osmotic pressure. Why is measurement of osmotic pressure method preferred for the determination of molar masses of macromolecules such as proteins and polymers?

Hint:

Osmotic pressure is a useful method for determining molar masses of substances that are too large to volatilize or are not easily distilled.

Answer 1

Osmotic pressure is the force exerted by a solution across a semipermeable membrane separating it from a pure solvent. This phenomenon arises from solvent molecule migration from regions of lower solute concentration to those of higher concentration. Osmotic pressure is favored for ascertaining macromolecule molar masses due to its colligative nature, meaning it is contingent on the number of solute particles, not their identity. This technique is especially beneficial for large molecules like proteins and polymers, which may pose challenges for alternative analytical methods.