What factors affect the boiling point? (2024)

• Boiling point is the temperature where the liquid turns into vapour and vapour pressure is equal to the atmospheric pressure.
• The boiling point of a liquid depends on pressure, vapour pressure and molecular weight.

The factors affecting boiling point are shown below.

1. Pressure: Boiling point increases as the pressure increases. If external pressure is lower than the atmospheric pressure then the boiling point is less than the normal boiling point. It increases when the pressure is more than the atmospheric pressure.
2. Effect of impurities: The boiling point increases with the increase in impurities.
3. Intermolecular forces: If the forces are weak, then the boiling point is also low and if the forces are strong then the boiling is high.
4. Molecular weight: Boiling increases if the chain length of the molecule increases.
5. Branching: With the increase in branching, the boiling point decreases.