What do we call the pressure exerted by gas molecules above a liquid when the rates of vaporization and condensation are equal?

The pressure exerted by gas molecules above a liquid when the rates of vaporization and condensation are equal is known as vapor pressure. This phenomenon occurs when the number of molecules escaping from the liquid phase into the gas phase (vaporization) is balanced by the number of gas molecules returning to the liquid phase (condensation). At this equilibrium, the exerted pressure by the vapor in the space above the liquid is referred to as vapor pressure.

Vapor pressure is a critical concept in understanding how liquids behave under different conditions, including temperature and pressure changes. Higher temperatures typically lead to increased vapor pressure because more molecules have enough energy to escape into the vapor phase.

Knowing vapor pressure is essential for various applications, including safety calculations in fire scenarios, as it can influence how substances behave when heated or exposed to flames. Understanding this concept helps in the effective management of hazardous materials and the prevention of dangerous situations in firefighting.