Question

A solution containing 3 g of solute A (M=60 g/mol) in 1L solution is isotonic with a solution containing 8.5
of solute B in 500 mL solution. What is the molar mass of B? (Ans:342 g/mol)​

Answer 1

Answer:

Concept

Osmotic Pressure, π = CRT.

Two solutions are called isotonic if their osomotic pressure is same.

Solution

Since, Temperature is same. The solutions will be isotonic when :-

Let us find concentration of A.

Let us assume molar mass of B be m.

Hence, concentration of B will be :-

Equating concentration of both solutions :

Hence, Molar mass of B is 342 g.