Question

How does atmospheric pressure affect boiling points?

Answer 1

Hint: We know that the temperature at which vapor pressure of a liquid becomes equal to the vapor pressure surrounding the liquid and the liquid changes to its vapor state is termed as boiling point of the substance.

Complete step by step answer:
Let’s first discuss atmospheric pressure in detail. Atmospheric pressure is also known by the name of air pressure. This is the force exerted by air on a surface. An instrument called a barometer is used to measure atmospheric pressure.
Let’s discuss the effect of atmospheric pressure on the boiling point. We know that boiling point is achieved when vapour pressure of liquid equals to the atmospheric pressure. That means, increasing the atmospheric pressure results in an increase of boiling point and lowering of atmospheric pressure results in lowering of boiling point of the liquid.
Let’s discuss the reason behind the above phenomenon. The above phenomenon occurs because vapor pressure of water is dependent on temperature. It rises as temperature increases and lowers as temperature drops. We can also assume atmospheric pressure as a pressure that pushes the liquid in a container back into the container (prevents the transition to the gaseous phase). So, greater the pressure means that more force is pushing back the particles down to the container. So, we need to heat the liquid more to achieve boiling point.

Note: It is to be noted that on increasing the temperature boiling point of the liquid rises because when temperature increases, energy available for liquid molecules to undergo expansion into the gaseous phase also increases.