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The "(s)" annotation indicates equilibrium temperature of vapor over solid. Otherwise value is equilibrium temperature of vapor over liquid. log 10 of Cyclohexane vapor pressure.
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).
Lee [4] developed a modified form of the Antoine equation that allows for calculating vapor pressure across the entire temperature range using the acentric factor (𝜔) of a substance. The fundamental structure of the equation is based on the van der Waals equation and builds upon the findings of Wall [ 5 ] and Gutmann et al. [ 6 ] , who ...
The C coefficient is useful for vapor-liquid equilibria data as well. The use of such an expression ignores the fact that on a molecular level the energy, , is temperature independent. It is a correction to repair the simplifications, which were applied in the derivation of the model.
The low-temperature (below 186 K) phase II is ordered. Two other low-temperature (metastable) phases III and IV have been obtained by application of moderate pressures above 30 MPa, where phase IV appears exclusively in deuterated cyclohexane (application of pressure increases the values of all transition temperatures). [15]
The Lee–Kesler method [1] allows the estimation of the saturated vapor pressure at a given temperature for all components for which the critical pressure P c, the critical temperature T c, and the acentric factor ω are known.
The acentric factor ω is a conceptual number introduced by Kenneth Pitzer in 1955, proven to be useful in the description of fluids. [1] It has become a standard for the phase characterization of single and pure components, along with other state description parameters such as molecular weight, critical temperature, critical pressure, and critical volume (or critical compressibility).
The atmospheric pressure boiling point of a liquid (also known as the normal boiling point) is the temperature at which the vapor pressure equals the ambient atmospheric pressure. With any incremental increase in that temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure and cause the liquid to form vapor bubbles.