A solution containing 15 g urea (molar mass = 60 g mol–1) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass = 180 g mol–1) in water. Calculate the mass of glucose present in one litre of its solution.
For isotonic solution
π1 = π2
C1 = C2 (at same temperature)
or n1 = n2 (is same volume)
x = 45 g, mass of glucose per liter of solution.
Osmotic pressure π = CRT =`(n2)/VRT`
where n is the number of moles of solute present in volume V of solvent.
It is given that the solution of urea is isotonic with the solution of glucose, thus
Hence, the mass of glucose present in one litre of its solution = 45 g