Corresponding-states equations

Whereas this two-parameter equation states the same conclusion as the van der Waals equation, this derivation extends the theory beyond just PVT behavior. Because the partition function, can also be used to derive aH the thermodynamic functions, the functional form, E, can be changed to describe this data as weH. Corresponding states equations are typicaHy written with respect to temperature and pressure because of the ambiguities of measuring volume at the critical point. 

Miscellaneous Generalized Correlations. Generalized charts and corresponding states equations have been pubhshed for many other properties in addition to those presented. Most produce accurate results over a wide range of conditions. Some of these properties include (/) transport properties (64,91) (2) second virial coefficients (80,92) (J) third virial coefficients (72) (4) Hquid mixture activity coefficients (93) (5) Henry s constant (94) and 6) diffusivity (95). 

The estimated values from the above equation for y of different n-alkanes were found to agree with the measured data within a few percent y for n-Ci8H3g, at 100°C, was 21.6 mN/m, both measured and calculated. This shows that the surface tension data of n-alkanes fit the corresponding state equation very satisfactorily (Table 3.6). In this analysis the pressure is assumed to be constant. Furthermore, by using this relationship, we do not need any elaborate tables of data. Especially by using a computer program we can find y values rapidly and accurately, as a function of both ric and T. However, the effect of pressure must not be considered negligible, as delineated later. More... 

The important thing to notice about this equation is that nothing in the integral depends on the properties of a specific fluid, so that when the integral is evaluated using the corresponding-states equation of state, the result will be applicable to all corresponding-states fluids. 

If the value of the viscosity is not found in the literature the corresponding state equations can be used, as illustrated already in Chapter 3. 

Reducing variables p y p Reducing variables are characteristic materials parameters used to reduce the corresponding independent variables, making them to follow respective corresponding state equation(s)... 

Experimental evidence has shown that the two-parameter corresponding-states equation is obeyed only by the higher molar mass noble gases (Ar, Kr and Xe) and nearly spherical molecules such as methane, nitrogen and oxygen. In order to extend the corresponding-states theory to a larger spectrum of fluids, additional characterization parameters have been introduced into the... 

The curves for Pr < 1 terminate at a curve representing orthobaric densities. The latter curve can itself be predicted using the Principle of Corresponding States equations for this purpose have been proposed by Guggenheim. ... 

Results from the extended corresponding states equation (11). 

Redlich-Kwong Equation. This equation, proposed by Redlich and Kwong (1949) has two adjustable parameters auid is convenient to use as a corresponding state equation. It is ... 

NBS Extended Corresponding States Equation Of State, APCI CAPP Ithermo 19, Dry Air Composition (Mole %) ... 

A compressibility factor can be defined that can capture corresponding states equations ... 

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