# Colligative Properties of Solutions

### Problems and Solutions

Problem :

What is the vapor pressure of the pure solvent if the vapor pressure of a solution of 10 g of sucrose (C6H12O6) in 100 g of ethanol (C2H6O) is 55 mmHg?

Problem :

What is the freezing point of a solution of 15.0 g of NaCl in 250 g of water? The molal freezing point constant, Kf, for water is 1.86 oC kg / mol.

Problem :

A solution of 0.5 g of an unknown nonvolatile, nonelectrolyte solute is added to 100 mL of water and then placed across a semipermeable membrane from a volume of pure water. When the system reaches equilibrium, the solution compartment is elevated 5.6 cm above the solvent compartment. Assuming that the density of the solution is 1.0 g / mL, calculate the molecular mass of the unknown.

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