Question

The most suitable property for molecular weight determination of polymers is:

• A. osmotic pressure
• B. lowering of vapour pressure
• C. elevation in boiling point
• D. depression in freezing point

Answer 1

The correct option is A osmotic pressure

The osmotic pressure method is quite advantageous over other methods for determination of molecular weight of high molecular masses as pressure measurement is around room temperature and the molarity of solution is used instead of molality.

As compared to other colligative properties, its magnitude is large even for very dilute solutions. The technique of osmotic pressure for determination of molar mass of solutes is particularly useful for biomolecules as they are generally not stable at high temperatures and polymers have poor solubility.