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759.9625. 1.0000. The vapor pressure of water is the pressure exerted by molecules of water vapor in gaseous form (whether pure or in a mixture with other gases such as air). The saturation vapor pressure is the pressure at which water vapor is in thermodynamic equilibrium with its condensed state. At pressures higher than vapor pressure, water ...
This is illustrated in the vapor pressure chart (see right) that shows graphs of the vapor pressures versus temperatures for a variety of liquids. [7] At the normal boiling point of a liquid, the vapor pressure is equal to the standard atmospheric pressure defined as 1 atmosphere, [ 1 ] 760 Torr, 101.325 kPa, or 14.69595 psi.
The Clausius–Clapeyron equation [7]: 509 applies to vaporization of liquids where vapor follows ideal gas law using the specific gas constant and liquid volume is neglected as being much smaller than vapor volume V. It is often used to calculate vapor pressure of a liquid. [8]
The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances. The Antoine equation is derived from the Clausius–Clapeyron relation. The equation was presented in 1888 by the French engineer Louis Charles Antoine [fr] (1825–1897). [1]
Values are given in terms of temperature necessary to reach the specified pressure. Valid results within the quoted ranges from most equations are included in the table for comparison. A conversion factor is included into the original first coefficients of the equations to provide the pressure in pascals (CR2: 5.006, SMI: -0.875).
The Tetens equation is an equation to calculate the saturation vapour pressure of water over liquid and ice. It is named after its creator, O. Tetens who was an early German meteorologist. He published his equation in 1930, [1] and while the publication itself is rather obscure, the equation is widely known among meteorologists and ...
Goff–Gratch equation. The Goff–Gratch equation is one (arguably the first reliable in history) amongst many experimental correlation proposed to estimate the saturation water vapor pressure at a given temperature. Another similar equation based on more recent data is the Arden Buck equation.
Reid vapor pressure (RVP) is a common measure of the volatility of gasoline and other petroleum products. [1] It is defined as the absolute vapor pressure exerted by the vapor of the liquid and any dissolved gases/moisture at 37.8 °C (100 °F) as determined by the test method ASTM-D-323, which was first developed in 1930 [2] and has been revised several times (the latest version is ASTM D323 ...