Question

What is the relationship between Boiling point and Vapour pressure ?

Answer 1

1. Vapour pressure is the ability of any liquid to change into its gaseous or vapour state.
2. As the liquid evaporates then the pressure exerted by the vapours known as vapour pressure, increases.
3. The boiling point is the temperature at which the vapour pressure is equal to the atmospheric pressure.
4. On heating continuously, the vapour pressure increases.
5. As we increase the temperature, more and more molecules go to vapour phase and vapours become dense.
6. Therefore, vapour pressure increases as we increase the temperature.
7. If the intermolecular forces are weak, then the liquid will have high vapour pressure and hence low temperature will be required to break the molecules and hence boiling point will be low.
8. Therefore, vapour pressure and boiling point are inversely related to each other.