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11/09/2020 12:07 pm
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An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?
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11/09/2020 12:12 pm
At boiling point, the vapour pressure of pure water is 1 atm or 1.004 bar.
Vapour pressure of solution is 1.004 bar.
Mass of solute is 2 g.
Mass of solution is 100 g.
Mass of solvent is 100 - 2 = 98 g
Applying Raoult's law, we get
Po - p/p = x2 = W2M1/M2W1
1.013-1.004/1.013 = 2 x 18/M2 x 98
=> M2 = 41.35 g/mol