Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# 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. - Chemistry

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.

#### Solution 1

For isotonic solution

π1 = π2

C1 = C2 (at same temperature)

or n1 = n2 (is same volume)

15/60=x/180

x = 45 g, mass of glucose per liter of solution.

#### Solution 2

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

(n_

=>(n_

=>(w_

=>w_

Hence, the mass of glucose present in one litre of its solution = 45 g

Concept: Colligative Properties and Determination of Molar Mass - Osmosis and Osmotic Pressure
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