 # Solutions Class 12 Notes - Chapter 2

A solution comprises of a solute and a solvent. It is defined as a homogeneous mixture of two or more than two substances. They can be classified into three types:

• Solid solutions
• Gaseous solutions
• Liquid solutions

Molarity, mole fraction, percentages, and molality are the terms used to express the concentration of a solution.

## Henry’s law

In liquids, the dissociation of gas is controlled by Henry’s law. The states that, the solubility of a gas in a liquid, at a given temperature, is directly proportional to the partial pressure of the gas. Due to the presence of a non-volatile solute, the vapor pressure of the solvent is lowered.

## Raoult’s Law

The lowering of the vapor pressure of the solvent is ruled by Raoult’s law. The law states that the relative lowering of the vapor pressure of the solvent over a solution and the mole fraction of a non-volatile solute present in the solution is equal. It is expressed as:

Ptotal= p10x1+p20x2

## Ideal Solutions

When a solution obeys Raoult’s law over the entire range of concentrations it is called an ideal solution. Types of deviations from Raoult’s law:

• Positive deviations
• Negative deviations

### Few Important Questions

1. What is mole fraction?
2. Explain the role of molecular interaction in a solution of water and alcohol?
3. Give the statement of Henry’s law. List some applications.
4. What is a solution? Explain the different types of solution.
5. What is molarity?