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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.
A saturation dome uses the projection of a P–v–T diagram (pressure, specific volume, and temperature) onto the P–v plane. The points that create the left-hand side of the dome represent the saturated liquid states, while the points on the right-hand side represent the saturated vapor states (commonly referred to as the “dry” region).
p is the pressure; V is the volume; n is the amount of substance of gas (moles) R is the gas constant, 8.314 J·K −1 mol −1; T is the absolute temperature; To simplify, a volume of gas may be expressed as the volume it would have in standard conditions for temperature and pressure, which are 0 °C (32 °F) and 100 kPa. [2]
The two first partial derivatives of the vdW equation are | = = | = + = where = is the isothermal compressibility (a measure of the relative increase of volume from an increase of pressure, at constant temperature), and = is the coefficient of thermal expansion (a measure of the relative increase of volume from an increase of temperature, at ...
The Clausius–Clapeyron equation [8]: 509 applies to vaporization of liquids where vapor follows ideal gas law using the ideal 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. [9]
The vapour pressure above the curved interface is then higher than that for the planar interface. This picture provides a simple conceptual basis for the Kelvin equation. The change in vapor pressure can be attributed to changes in the Laplace pressure. When the Laplace pressure rises in a droplet, the droplet tends to evaporate more easily.
A nice feature with the volume translation method of Peneloux et al. (1982) is that it does not affect the vapor–liquid equilibrium calculations. [9] This method of volume translation can also be applied to other cubic EOSs if the c-parameter correlation is adjusted to match the selected EOS.
To exactly calculate the work done by the system it is necessary to calculate the integral of the pressure with respect to volume. One can often quickly calculate this using the PV diagram as it is simply the area enclosed by the cycle. [citation needed] Note that in some cases specific volume will be plotted on the x-axis instead of volume, in ...