Pressure Vapor pressure

Vapor Pressure pressure exerted by a liquid or solid s vapor when the liquid or solid is in equilibrium with its vapor Vaporization evaporation, process that occurs when molecules pass from liquid to gaseous state... 

Vapor pressure Pressure at which a liquid and its vapor are in equilibrium at a given temperature. 

Vapor Pressure Pressure exerted by the vapor of a liquid as the molecules of the liquid evaporate. 

Strictly speaking, the enthalpies tabulated in A.2-9 are for saturated Uquid, meaning that the pressure on the liquid equals the vapor pressure. Here the pressure on the feed is probably 1 atm (or 14.7 psia) rather than 0.3622 psia (the vapor pressure). Pressure has a very weak effect on the enthalpy of Uquid water and the effect of pressure usually neglected. For example, the effect of a change on pressure equal to latm on the enthapy of Uquid water can be estimated as... 

Liquid vapor pressure Pressure at which Hquid vaporizes. 

Pressure gradient Temperature gradient Vapor pressure Vapor pressure Pressure gradient Concentration gradient Gradient of electric potential Concentration gradient Pressure gradient and... 

At equilibrium, the molecules in the vapor exert a pressure like any other gas. The pressure exerted by a vapor in equilibrium with its liquid is known as the vapor vapor pressure pressure of the liquid. The vapor pressure may be thought of as a measure of the escaping tendency of molecules to go from the liquid to the vapor state. The vapor pressure of a liquid is independent of the amount of liquid and vapor present, but it increases as the temperature rises. We can measure the vapor pressure of a liquid by using a simple barometer as shown in Figure 13.4. Mercury is so dense that if we inject a sample of liquid at the bottom of the Hg tube, the liquid rises to the top of the Hg column. It is than trapped in a closed space where it produces a vapor that pushes down the Hg column. When equilibrium between the liquid and vapor is reached, we can measure the vapor pressure by the change in height of the Hg column. 

Vapor Pressure Pressure exerted by gas in equilibrium with its liquid phase. 

The polymerization takes place in an autoclave resistant to the VCM vapor pressure. Pressures of 6.4-10.0 bar correspond to polymerization temperatures of 40-60°C, depending on the desired molecular mass. The polymerization reaction... 

Vapor pressure Pressure exerted by a vapor. If a vapor is kept in confinement over its liquid so the vapor can accumulate above the liquid (the temperature being held constant), the vapor pressure approaches a fixed limit call the maximum (or saturated vapor pressure, dependent only on the temperature and the liquid. 

American Petroleum Institute, Bibliographies on Hydrocarbons, Vols. 1-4, "Vapor-Liquid Equilibrium Data for Hydrocarbon Systems" (1963), "Vapor Pressure Data for Hydrocarbons" (1964), "Volumetric and Thermodynamic Data for Pure Hydrocarbons and Their Mixtures" (1964), "Vapor-Liquid Equilibrium Data for Hydrocarbon-Nonhydrocarbon Gas Systems" (1964), API, Division of Refining, Washington. 

Boublik, T., V. Fried, and E. Hala "The Vapor Pressure of Pure Substances," Elsevier, Amsterdam, 1973. 

Compilation of physical properties for 321 heavy hydrocarbons. Vapor pressures at low pressures. ... 

Correlation and compilation of vapor-pressure data for pure fluids. Normal and low pressure region. 

Source for liquid-liquid and vapor-liquid equilibrium data and vapor-pressure data. 

Jordan, T. E. "Vapor Pressure of Organic Compounds," Interscience, New York, 1954. 

Compilation of vapor-pressure data for organic compounds data are correlated with the Antoine equation and graphs are presented. 

Vapor-liquid equilibrium data and vapor pressure data, Vol. 2 (2a) and Vol. 4 (4b) and liquid-liquid equilibrium data, Vol. 2 (2b, 2c). 

Nesmeyanov, A. N. "Vapor Pressure of the Chemical Elements," Elsevier, New York, 1963. 

Vapor-pressure data correlated with the Antoine equation. Results displayed graphically. 

Vapor-pressure data and other thermodynamic properties. 

Wichterle, I., and J. Linek "Antoine Vapor Pressure Constants of Pure Compounds," Academia, Prague, 1971. 

Presents vapor-pressure data for a large number of substances. 

Presents Antoine vapor-pressure constants for pure compounds for two pressure ranges. 

Zwolinski, B. J., and R. C. Wilhoit "Vapor Pressures and Heats of Vaporization of Hydrocarbons and Related Compounds," Thermodynamic Research Center, Dept, of Chemistry, Texas A M University, College Station, Texas, 1971. 

Compilation of vapor pressures of organic and related compounds to one atmosphere. 

Normally, Henry s constant for solute 2 in solvent 1 is determined experimentally at the solvent vapor pressure Pj. The effect of pressure on Henry s constant is given by... 

P the other terms provide corrections which at low or moderate pressure are close to unity. To use Equation (2), we require vapor-pressure data and liquid-density data as a function of temperature. We also require fugacity coefficients, as discussed in Chapter 3. 

Enthalpies are referred to the ideal vapor. The enthalpy of the real vapor is found from zero-pressure heat capacities and from the virial equation of state for non-associated species or, for vapors containing highly dimerized vapors (e.g. organic acids), from the chemical theory of vapor imperfections, as discussed in Chapter 3. For pure components, liquid-phase enthalpies (relative to the ideal vapor) are found from differentiation of the zero-pressure standard-state fugacities these, in turn, are determined from vapor-pressure data, from vapor-phase corrections and liquid-phase densities. If good experimental data are used to determine the standard-state fugacity, the derivative gives enthalpies of liquids to nearly the same precision as that obtained with calorimetric data, and provides reliable heats of vaporization. 

This chapter presents quantitative methods for calculation of enthalpies of vapor-phase and liquid-phase mixtures. These methods rely primarily on pure-component data, in particular ideal-vapor heat capacities and vapor-pressure data, both as functions of temperature. Vapor-phase corrections for nonideality are usually relatively small. Liquid-phase excess enthalpies are also usually not important. As indicated in Chapter 4, for mixtures containing noncondensable components, we restrict attention to liquid solutions which are dilute with respect to all noncondensable components. 

An apparent systematic error may be due to an erroneous value of one or both of the pure-component vapor pressures as discussed by several authors (Van Ness et al., 1973 Fabries and Renon, 1975 Abbott and Van Ness, 1977). In some cases, highly inaccurate estimates of binary parameters may occur. Fabries and Renon recommend that when no pure-component vapor-pressure data are given, or if the given values appear to be of doubtful validity, then the unknown vapor pressure should be included as one of the adjustable parameters. If, after making these corrections, the residuals again display a nonrandom pattern, then it is likely that there is systematic error present in the measurements. ... 

Correlations for standard-state fugacities at 2ero pressure, for the temperature range 200° to 600°K, were generated for pure fluids using the best available vapor-pressure data. 

The correlations were generated by first choosing from the literature the best sets of vapor-pressure data for each fluid. 

These were converted from vapor pressure P to fugacity using the vapor-phase corrections (for pure components), discussed in Chapter 3 then the Poynting correction was applied to adjust to zero pressure ... 

The user may also choose to use the vapor-pressure equation instead of the fugacity at zero pressure. 

If the data are correlated assuming an ideal vapor, the reference fugacity is just the vapor pressure, P , the Poynting correction is neglected, and fugacity coefficient is assumed to be unity. Equation (2) then becomes... 

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