Væskegasspændingen

Væskegasspændingen, also known as vapor pressure, is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. It is a fundamental property of a substance. When a liquid is placed in a sealed container, some of its molecules will evaporate and enter the gaseous phase. As the number of gas molecules increases, they collide with the liquid surface and re-condense. Equilibrium is reached when the rate of evaporation equals the rate of condensation. At this point, the pressure exerted by the vapor is the væskegasspænding.

This pressure is dependent on the temperature; as temperature increases, the kinetic energy of the liquid molecules increases, leading to a higher rate of evaporation and thus a higher væskegasspænding. For solids, the equivalent concept is sublimation pressure. Væskegasspændingen is a crucial factor in many physical and chemical processes, including distillation, boiling, and the design of storage tanks for volatile substances. Different substances have different væskegasspændinger at the same temperature. For example, volatile liquids like acetone have a high væskegasspænding, while less volatile liquids like water have a lower væskegasspænding.