Definition - What does Vapor Pressure mean?
Vapor Pressure is the pressure exerted by the vapors on a liquid surface in thermodynamic equilibrium state. It is an indication of the evaporation rate of a liquid. Materials which have high Vapor Pressure at normal temperature are volatile in nature, whereas materials which have low Vapor Pressure at normal temperature are non-volatile in nature. Vapor Pressure follows the Clausius-Clapeyron relation meaning it increases nonlinearly with the increase in temperature.
Vapor Pressure is also known as Equilibrium Vapor Pressure. It relates to the tendency of a liquid to evaporate into gaseous form. The surface area of the liquid has no effect on Vapor Pressure, but it is affected by the type of molecules. If the intermolecular forces are strong such as in solids then the Vapor Pressure is low. Methyl chloride is one of the best examples to show the highest Vapor Pressure in terms of all the liquids which have the lowest boiling points. It is measured in standard units of pressure and is designated by Pascal.