An aqueous solution containing urea found to have boiling point more than the normal boiling point of water (373.13 K). When the same solution was cooled, it was found that its freezing point is less than the normal freezing point of watre (273.13K). Explain there observations.

Explanation

In aqueous solution, urea action as a non-volatile solute with very little vapour pressure of its own. However, it occupies some surgace area. Since evapouration is a surface phenomerna, the vapour pressure of the solutio gets reduced. This means that the solution has to be heated to a higher temperature so that the vapour pressure on its surface may match the atmospheric pressure that corresponds to the biling point temperature of the solution. In other words, the boiling point of the solution gets raise. For more detailos consult Section 10.
Reverse happents to the freezing point of the solution when teh same non-volatile solute is added to it. A solution freezes when the vapour pressure on its surface becomes equal to that of pure solvent. On adding a non-volalite solute, the vapour when the vapour pressure of the solution becomes equal to that of th pure sovent at a lower temperature. In other wards, freezing point temperature of dthe solution gets lowerd. For more details, consults Section 11.