Question

How do atmospheric pressure and elevation affect boiling point?

Answer 1

Elevation in Boiling point:-

1. The temperature at the pressure exerted by the surroundings upon a liquid is equalled by the pressure exerted by the vapour of the liquid is known as the boiling point.
2. The vapour pressure is the pressure exerted by the gas when the amount of particles leaving the liquid equals the number of particles present entering the liquid.
3. As temperature increases, more particles have enough energy to escape to the gas phase. This increases the vapour pressure. When the vapour pressure equals atmospheric pressure, the liquid boils.
4. As elevation increases, atmospheric pressure decreases because air is less dense at higher altitudes.
5. The atmospheric pressure is lower, and the vapour pressure of the liquid needs to be lower to reach the boiling point.
6. So, less heat is required to make the vapour pressure equal to atmospheric pressure. Hence, the boiling is lower at high altitudes.

Therefore, due to a decrease in atmospheric pressure the boiling point is lower at higher altitudes.