Question

PROVE THAT OSMOTIC PRESSURE IS A COLLIGATIVE PROPERTY . WHY THIS METHOD IS USED TO DETERMINE THE MOLAR MASS OF MACROMOLECULES

Answer 1

HELLO DEAR..!!!


Firstly, colligative properties are the properties of solutions which depend upon the number of solutes particles in the solution irrespective of their nature. So, osmotic pressure is also a colligative property as it is proportional to the molarity( number of moles in one lifter solution)  and temperature of a solution according to the following equation:
πV=nRT  (basic equation for the ideal solutions)
or,
π=CRT
where, n/V = C
π is the osmotic pressure
C is the concentration i.e. n/V
V is the volume
T is the absolute temperature
n is the number of moles of solute in a solution
R is the gas constant 8.314 J K-1 mol-1
Therefore, osmotic pressure is directly proportional of the number of moles(or concentration) of the solute. Hence, it is a colligative property.


 it is done at room temperature
the concentration term is molarity which is easy to handle at lab level
the numerical value for osmotic pressure comes out to be large even for dilute solutions and hence reduce the % error
also in case of polymers since they have very  high molar masses they give very less value of the colligative properties which leads to more error but osmotic pressure values are significant enough for higher molar masses.

hope it helps :)