How does vapor pressure affect the boiling point of a liquid?
Vapor pressure is the pressure exerted by a certain amount of gas in equilibrium with the liquid and solid phases of a substance, and is proportional to the amount of gas present.
There are 3 key ideas to understand here:
1) Boiling point is the temperature at which a substance changes from liquid to gas.
2) Molecules in a liquid sample will transition to a gas when their vapor pressure is equal to the surrounding .
3) The Vapor Pressure of the substance changes with temperature. (higher temperature, increase in VP)
When you put this all together, it means that there is a temperature that exists where the vapor pressure of a substance is equal to the surrounding atmospheric pressure… we call that temperature the boiling point.