Chemistry 12
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    After studying this Unit, you will be able
    · describe the formation of different types of solutions;
    · express concentration of solution in different units;
    · state and explain Henry’s law and Raoult’s law;
    · distinguish between ideal and non-ideal solutions
    · explain deviations of real solutions from Raoult’s law;
    · describe colligative properties of solutions and correlate these with molar masses of the solutes;
    · explain abnormal colligative properties exhibited by some solutes in solutions.

1.1 Types of Solutions
1.2 Expressing Concentration of Solutions
1.3 Solubility
1.3.1 Solubility of a Solid in a Liquid
1.3.2 Solubility of a Gas in a Liquid
1.4 Vapour Pressure of Liquid Solutions
1.4.1 Vapour Pressure of Liquid-Liquid Solutions
1 .5 Ideal and Nonideal Solutions
1.4.3 Vapour Pressure of Solutions of Solids in Liquids
1 .5 Ideal and Nonideal Solutions
1.5.1 Ideal Solutions
1.5.2 Non-ideal Solutions
1.6 Colligative Properties and Determination of Molar Mass
1.6.1 Relative Lowering of Vapour Pressure
1.6.2 Elevation of Boiling Point
1.6.3 Depression of Freezing Point
1.6.4 Osmosis and Osmotic Pressure
1.6.5 Reverse Osmosis and Water Purification
1.7 Abnormal Molar Masses

ℹ️ Henry’s law
The solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of liquid or solution.
The most commonly used form of Henry’s law states that
“the partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution”
and is expressed as: $p = K_H x$ Here $K_H$ is the Henry’s law constant.

Solubility of gases in liquids decreases with rise in temperature.

ℹ️ Raoult’s law
For a solution of volatile liquids, the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution.
$p_{total} = x_1 p_1^0 + x_2 p_2^0$
(i) Total vapour pressure over the solution can be related to the mole fraction of any one component.
(ii) Total vapour pressure over the solution varies linearly with the mole fraction of component 2.
(iii) Depending on the vapour pressures of the pure components 1 and 2, total vapour pressure over the solution decreases or increases with the increase of the mole fraction of component 1.

Decrease in the vapour pressure of the solvent on account of the presence of solute in the solvent as evaporation of the molecules of the solvent from its surface decreases.

When a solution does not obey Raoult’s law over the entire range of concentration, then it is called non-ideal solution.

Minimum boiling azeotrope and Maximum boiling azeotrope.

The solutions which show a large positive deviation from Raoult’s law form minimum boiling azeotrope at a specific composition

The solutions that show large negative deviation from Raoult’s law form maximum boiling azeotrope at a specific composition.
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