What is vapor pressure?

Vapor pressure refers to the pressure exerted by the molecules of a vapor in equilibrium with its liquid or solid phase at a given temperature. This concept is vital in understanding phase transitions and thermodynamic principles involving substances in their gaseous state. At a certain temperature, some molecules in a liquid escape into the gas phase, creating a vapor, and the vapor pressure is the result of these gas molecules exerting force on the walls of their container.

In scenarios involving liquids, vapor pressure can indicate how easily a substance can evaporate; a higher vapor pressure signifies a higher tendency for the liquid to enter the vapor phase. This is important in various applications, such as predicting how volatile a substance is or understanding how it behaves under different conditions in a measurement verification context.