Ideal mixture Gibbs energy

For the Gibbs energy of an ideal gas mixture, — T the parallel relation for partial properties is equation 149 ... 

A.ctivity Coefficients. Activity coefficients in Hquid mixtures are directiy related to the molar excess Gibbs energy of mixing, AG, which is defined as the difference in the molar Gibbs energy of mixing between the real and ideal mixtures. It is typically an assumed function. Various functional forms of AG give rise to many of the different activity coefficient models found in the Hterature (1—3,18). Typically, the Hquid-phase activity coefficient is a function of temperature and composition expHcit pressure dependence is rarely included. 

Figure 7.1 Entropy, enthalpy, and Gibbs free energy changes at T= 298.15 K for forming one mole of an ideal mixture from the components,...

The Gibbs free energy (computed in the harmonic approximation) were converted from the 1 atm standard state into the standard state of molar concentration (ideal mixture at 1 molL-1 and 1 atm). 

The partial molar Gibbs energy of mixing of a component i in a non-ideal mixture can in general be expressed in terms of activity coefficients as... 

Partial molar availability, 24 692 Partial molar entropy, of an ideal gas mixture, 24 673—674 Partial molar Gibbs energy, 24 672, 678 Partial molar properties, of mixtures, 24 667-668... 

The chemical potential, p, of a component of the mixture is the partial derivative of the Gibbs energy of the mixture with respect to the number of moles of this component present, the number of moles of all the other components being held constant, as are also the temperature and the pressure. For the component A in a mixture containing also B, C,.. ., the chemical potential is Pa = (dG/3 A)p,r,nB.nc. whether the mixture is ideal or not. In the ideal mixture the chemical potential of A is thus obtained from Eqs. (2.15) and (2.16) on carrying out the partial differentiation, yielding ... 

Figure 3.9 Conformation of Gibbs free energy curve in various types of binary mixtures. (A) Ideal mixture of components A and B. Standard state adopted is that of pure component at T and P of interest. (B) Regular mixture with complete configurational disorder kJ/mole for 500 < r(K) < 1500. (C) Simple mixture IF = 10 - 0.01 X r(K) (kJ/ mole). (D) Subregular mixture Aq = 10 — 0.01 X T (kJ/mole) = 5 — 0.01 X F (kJ/ mole). Adopting corresponding Margules notation, an equivalent interaction is obtained with IFba = 15 - 0.02 X r(kJ/mole) Bab = 5 (kJ/mole).

One of the earliest examples of Gibbs energy minimisation applied to a multi-component system was by White et al. (1958) who considered the chemical equilibrium in an ideal gas mixture of O, H and N with the species H, H2, HjO, N, N2, NH, NO, O, O2 and OH being present. The problem here is to find the most stable mixture of species. The Gibbs energy of the mixture was defined using Eq. (9.1) and defining the chemical potential of species i as... 

An ideal mixture of molten salts is a mixture for which the heat of mixing, energy of mixing and variation of volume of mixing have the value zero. Certainly, in practice there are no such ideal mixtures. The Gibbs energy of mixing... 

Tliis equation takes on a new dimension when G f, the Gibbs energy of pure species i m the ideal-gas state, is replaced by Gj, tire Gibbs energy of pure species i as it actually exists at tire mixhire T and P and hr tire same physical state (real gas, liquid, or solid) as the mixture. It then applies to species in real solutions. We therefore define an ideal solution as one for which ... 

However, even for an ideal mixture, there is an effect on the Gibbs free energy from the entropy of mixing, namely. 

The partial molar Gibbs energy or chemical potential of species i in an ideal gas mixture is given by Eq. (4-195), written as... 

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