Question

What is the relationship between boiling point and vapour pressure?

Answer 1

Hint: We have to know that the boiling point of a liquid is the temperature required to boil and it is converted to gas. Here, the liquid is converted into a gaseous state. Which means, a phase transition takes place from liquid phase to gaseous phase. All the substances have different boiling points according to their properties. And the vapour pressure is the tendency of a substance to change into the vapour state or gaseous state. The vapour pressure increases with increasing temperature.

Complete answer:
As we know, when the specific temperature at which the vapour pressure of the given liquid becomes equal to the atmospheric pressure, then it is called boiling point. If the intermolecular forces are weak, then the vapour pressure of the liquid will be very high. That time, very less energy is required to separate or break the molecules. Hence, the boiling point will decrease. But, as the intermolecular forces increase, the vapour pressure of the liquid also increases. Because it requires more energy to break the molecules. Therefore, the boiling point of the liquid is increasing. Hence, we can say that the boiling point of a liquid is increasing with increasing the vapour pressure as well as the intermolecular forces.

Note:
We have to know that the boiling point is the required temperature to boil the liquid and it converts into vapour state or gaseous state. The boiling point increases with increasing vapour pressure. Because, when the vapour pressure increases, there is also increasing the intermolecular forces of attraction. Hence, it needs more energy to break the molecules. Then, we have to apply more temperature to boil a liquid. Therefore, we can say that the boiling point is directly proportional to the vapour pressure.