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Fugacity pressure variation

It is clear from Eq. 11.1-9 that the Henry s law constant will vary with pressure, since f - and y are functions of pressure. The common method of accounting for this pressure variation is to define the Henry s law constant to be specific to a fixed pressure- Pq (frequently taken to be atmospheric pressure) and then include a Poynting correction for other pressures. Independent of whether we apply the correction to the fugacity of. the solute species in solution f T, P,x —> 0) or separately to the pure component fugacity and the infinite-dilution activity coefficient (see Eq. 9.3-20), we obtain... [Pg.583]

We have a considerable body of knowledge to help us to say something about the third coefficient, the variation of fugacity with composition. Many empirical and semiempirical expressions (e.g., Margules, Van Laar, Scat-chard-Hildebrand) have been investigated toward that end. Most of our experience in this regard is limited to liquid mixture at low pressures, where... [Pg.143]

In Section I, we indicated that significant progress in understanding high-pressure thermodynamics of mixtures requires a quantitative description of the variation of fugacity with pressure as given by Eq. (3). To obtain the effect of pressure on activity coefficient we substitute as follows ... [Pg.160]

Fig. 2.4. Example of a sliding-fugacity path. Deep groundwaters of a geopressured zone in a sedimentary basin migrate upward to lower pressures. During migration, CO2 exsolves from the water so that its fugacity follows the variation in total pressure. The loss of CO2 causes carbonate cements to form. Fig. 2.4. Example of a sliding-fugacity path. Deep groundwaters of a geopressured zone in a sedimentary basin migrate upward to lower pressures. During migration, CO2 exsolves from the water so that its fugacity follows the variation in total pressure. The loss of CO2 causes carbonate cements to form.
For a solid component taking part in a reaction, fugacity variations with pressure are small and can usually be ignored. Hence... [Pg.211]

In our kinetic calculations, we refer to the directly observed partial pressure of propylene, rather than to its fugacity, because over the temperature and pressure range examined, we can assume that partial pressures and fugacities are practically proportional. In fact, from the literature data, the variation in propylene fugacity coefficient, in the range of our kinetic tests, is small (about 0.97 at 30° and 2700 mm. Hg about 0.99 at 70° and 450 mm. Hg of propylene partial pressure). [Pg.20]

As a consequence a small variation of the pressure causes a large variation of the fugacity coefficient and of the solubility. [Pg.49]

The water electrolysis rest potential is determined from extrapolation to ideal conditions. Variations of the concentration, c, and pressure, p, from ideality are respectively expressed by the activity (or fugacity for a gas), as a = yc (or yp for a gas), with the ideal state defined at 1 atmosphere for a pure liquid (or solid), and extrapolated from p = 0 or for a gas or infinite dilution for a dissolved species. The formal potential, measured under real conditions of c and p can deviate significantly from the (ideal thermodynamic) rest potential, as for example the activity of water, aw, at, or near, ambient conditions generally ranges from approximately 1 for dilute solutions to less than 0.1 for concentrated alkaline and acidic electrolytes.91"93 The potential for the dissociation of water decreases from 1.229 V at 25 °C in the liquid phase to 1.167 V at 100 °C in the gas phase. Above the boiling the point, pressure is used to express the variation of water activity. The variation of the electrochemical potential for water in the liquid and gas phases are given by ... [Pg.100]

As a first approximation, Cp may be treated as independent of the pressure, and if MJ.T. is expressed as a function of the pressure, it is posnble to carry out the integration in equation (29.24) alternatively, the integral may be evaluated graphically. It is thus posdble to determine the variation of the fugacity with temperature. [Pg.259]

By following the procedure given in 29f, with / representing the fugacity of pure liquid or solid, an equation exactly analogous to (29.22) is obtained for the variation of the fugacity with temperature at constant pressure. As before, H is the molar heat content of the gas, i.e., vapor, at low pressure, but H is now the molar heat content of the pure liquid or solid at the pressure P. The difference — H has been called the ideal heat of vaporization, for it is the heat absorbed, per mole, when a very small quantity of liquid or solid vaporizes into a vacuum. The pressure of the vapor is not the equilibrium value, but rather an extremely small pressure where it behaves as an ideal gas. [Pg.260]

The equations derived in 30c, 30d thus also give the variation with pressure and temperature of the fugacity of a constituent of a liquid (or solid) solution. In equation (30.17), Vi is now the partial molar volume of the particular constituent in the solution, and in (30.21), i is the corresponding partial molar heat content. The numerator — fti thus represents the change in heat content, per mole, when the constituent is vaporized from the solution into a vacuum (cf. 29g), and so it is the ideal" heat of vaporization of the constituent i from the given solution, at the specified temperature and total pressure. [Pg.268]

Heterogeneous physical equilibria, e.g., between a pure solid and its vapor or a pure liquid and its vapor, can be treated in a manner similar to that just described. If the total pressure of the system is 1 atm., the fugacity of the vapor is here also equivalent to the equilibrium constant. The variation of In/ with temperature is again given by equation (33.16), where MP is now the ideal molar heat of vaporization of the liquid (or of sublimation of the solid) at the temperature T and a pressure of 1 atm. If the total pressure is not 1 atm., but is maintained constant at some other value, the dependence of the fugacity on the temperature can be expressed by equation (29.22), since the solid or liquid is in the pure state thus,... [Pg.291]

The use of the foregoing definition of an ideal solution implies certain properties of such a solution. The variation of the fugacity / of a pure liquid i with temperature, at constant pressure and composition, is given by equation (29.22), viz.. [Pg.317]

An equation, somewhat similar to (35.6), was suggested by M. Margules (1895) to express the variation bf vapor pressure with composition of liquid mixtures in general replacing the vapor pressure by the fugacity, this can be written as... [Pg.334]

A formula for computing the variation of the fugacity of pure component i in the liquid phase with pressure at a given temperature is found by first restating Eq. (14-26) in the following form... [Pg.526]

Only the fugacity change with respect to pressure and temperature variation has been considered for the pure gases. For a mixed gas system, interactions between the different gas molecules and atoms must also be taken into account. The second virial coefficient, Bm(T), for a binary mixture between molecules 1 and 2 can be expressed as... [Pg.541]

So, for example, the isothermal variation of pressure with species 2 fugacity when integrating along coexistence in an osmotic ensemble can be read... [Pg.417]

A useful and widely-used variation of Raoult s Law is obtained by expressing it in terms of fugacities instead of pressures. Thus in some homogeneous (one phase)... [Pg.259]


See other pages where Fugacity pressure variation is mentioned: [Pg.710]    [Pg.328]    [Pg.502]    [Pg.149]    [Pg.179]    [Pg.119]    [Pg.182]    [Pg.247]    [Pg.291]    [Pg.502]    [Pg.11]    [Pg.182]    [Pg.8]    [Pg.163]    [Pg.392]    [Pg.50]    [Pg.1134]    [Pg.36]    [Pg.258]    [Pg.259]    [Pg.260]    [Pg.264]    [Pg.266]    [Pg.291]    [Pg.335]    [Pg.359]    [Pg.211]    [Pg.434]    [Pg.6]    [Pg.135]    [Pg.257]   
See also in sourсe #XX -- [ Pg.162 , Pg.163 ]

See also in sourсe #XX -- [ Pg.158 ]




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