Define relative lowering of vapour pressure.

Show that relative lowering of vapour pressure is a colligative property.

State Raould's law regarding relative lowering of vapour pressure. Why is said to be colligative property.

Why Raoults law for relative lowering of vapour pressure is not applicable for concentrate solution?

A solution is prepared by dissolving 10 g of nonvolatile solute in 180 g of H_2O . If the relative lowering of vapour pressure is 0.005, find the mol. wt. of the solute.

Addition of non-volatile solute to a solvent always increases the colligative properties such as osmotic pressure. Delta P . Delta T_b and Delta T_f . All these colligative properties are directly proportional to molality if solutions are dilute. The increases in colligative properties on addition of non-volatile solute is due to increases in number of solute particles. 1 g mixture of glucose and urea present in 250mL aqueous solution shows the osmotic pressure of 0.74 atm at 27^@C . Assuming solution to be dilute which are correct ? 1. Percentage of urea in mixture is 17.6. 2. Relative lowering in vapour pressure of this solution is 5.41 xx 10^(-4) . 3. The solution will boil at 100.015^@C . if k_b of water is 0.5 k molality^(-1) . 4. If glucose is replaced by same amount of sucrose the solution will show higher osmotic pressure at 27^@C . 5. If glucose is replaced by same amount of NaCI, the solution will show lower osmotic pressure at 27^@C .

When some NaCl was dissolved in water, the freezing point depression was numerically equal to twice the molal depression constant. The relative lowéring of vapour pressure of the solution is