Chemistry 1 Marks Question

Ideal solutions are those solutions which obeys Raoult's law at any concentration and temperature. Non-ideal solutions are those solution which do not follows Raoult's law.

Positive deviation.

Mole Fraction: It is the ratio of the number of moles of one component (i.e., solute or solvent) to the total number of moles of the solution (i.e., both the components). It is usually represented by x.

Osmotic Pressure: The excess pressure that must be applied to the solution side to prevent the passage of solvent into it through semi-permeable membrane.

For a solution containing a non-volatile solute, there is no contribution of the solute to the total vapour pressure of the solution. Therefore, the vapour pressure of the solution will be the vapour pressure due to solvent only. Vapour Pressure of the Solution = Vapour Pressure of the Solvent in the Solution.

Reverse Osmosis: If an external pressure higher than the osmotic pressure is applied, the process of osmotic is reversed i.e., solvent start flowing from solution into the pure solvent higher to lower concentration. One application of reverse osmosis is desalination of sea water.

Freezing point: It is that temperature of a liquid at which it begins to solidify. At this temperature vapour pressure becomes zero.
Depression in freezing point: When a non-volatile solute is added, the vapour pressure of solution is lowered. With decrease in vapour pressure the freezing point also decreases. It is known as depression in freezing point.

Molal elevation constant: It is elevation of boiling point temperature for 1 molal solution.