Question

How do atmospheric pressure and elevation affect boiling point?

Answer 1

Boiling point is the temperature at which its vapour pressure is equal to the pressure of gas above it. The greater the pressure, the more energy required for liquids to boil and the higher the boiling point. As elevation increases, atmospheric pressure decreases because air is less dense at higher altitudes.

Complete step by step answer:
The boiling point is the temperature at which the vapour pressure of a liquid equals the pressure surrounding the liquid and liquid changes into vapour. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid t high pressure has a higher boiling point than when that liquid is at atmospheric pressure.
The vapour pressure is the pressure exerted by the gas when the amount of particles leaving the liquid equals the amount of particles entering the liquid. As temperature increases, more particles move to form gas phases. This increases the vapour pressure. When the vapour pressure equals atmospheric pressure, the liquid boils.
At higher altitudes air is less dense and hence pressure of air decreases. Since atmospheric pressure is lowered, vapour pressure of liquid needs to be lower to reach boiling point. Therefore less heat is required to make the vapour pressure equal to the atmospheric pressure. The boiling point is lower at higher altitude.

Additional Information:
Atmospheric pressure varies widely on earth, and these changes are important in studying weather and climate. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. Pressure measures force per unit area, with SI unit pascals. The normal boiling point of a liquid is the temperature at which its vapor pressure is equal to one atmosphere. The heat of vaporization is the energy required to transform a given quantity of a substance from liquid into a gas at a given pressure. Boiling is a process in which molecules anywhere in the liquid escape, resulting in formation of vapour bubbles within liquid.

Note: A liquid in a partial vacuum has a lower boiling point that when that liquid is at atmospheric pressure. Temperature and humidity also affect the atmospheric pressure. The type of molecules that make up a liquid determine its boiling point. If molecular forces are strong boiling point is high and if boiling point is less it means weak molecular forces. The temperature of a boiling liquid remains constant, when more heat is added. The critical point of a liquid is the highest temperature it will actually boil at. The element with the lowest boiling point is hdium.