Change of Gibbs energy on mixing

The quantity AGM is called the change of Gibbs energy on mixing at constant temperature and pressure or, more briefly, the Gibbs energy of mixing. 

Hence, the minimum isothermal-isobaric work needed to separate a mixture into its pure components is given by the negative change of Gibbs energy on mixing. Note that (3.7.37) is not limited to any particular phase it applies to solids, liquids, and gases. In Chapter 6 we will show how to evaluate the differences in (3.7.37) and (3.7.38) for particular classes of mixtures. 

Figure 8.15 Change of Gibbs energy on mixing for class II stability behavior at constant T and P. Both the mixture equation of state and the fugadty equation bifurcate, producing distinct branches in and a vapor-Uquid phase separation. However, no branch spans all x. Filled circles are phases in equilibrium long dashes metastable short dashes unstable. Curves computed using Redlich-Kwong equation.

Sketch an isothermal-isobaric plot of the change of Gibbs energy on mixing g>" vs. mole fraction Xj for a binary mixture in three-phase vapor-liquid-liquid equilibrium. Include the tie lines on your plot and indicate the compositions of the... 

In (8.4.2) and (8.4.3) the conditions for a binary critical point are given in terms of the change of Gibbs energy on mixing. Those conditions can also be expressed in terms of the fugacity of either component. 

Consider a binary mixture that has = 0 and h /RT = 0.6 ci c2 with the ideal solution relative to the Lewis-Randall standard state. Find the expression for the composition dependence of g , the change in Gibbs energy on mixing. 

For binary mixtures it is conventional to express the conditions for the critical point in terms of the change in Gibbs energy on mixing (3.7.38) ... 

In review, we see that, for an ideal solution, the change of the Gibbs energy on mixing and the change of the entropy on mixing both at constant... 

The change of Gibbs free energy on mixing is then... 

When considering mixtures of two or more components, the thermodynamics of the mixtures is often cast in the form of changes in quantities on mixing. The change in Gibbs free energy on mixing at constant temperature and pressure is defined as... 

A Volume Change on Mixing. The criterion for miscibility of two materials mixed at constant temperature (T) and pressure (p) is that the change in the Gibbs free energy on mixing, AG, must be less than or eqiml to zero. AG is related to the associated changes in... 

It is traditional to base determinations of phase stability on the change in Gibbs energy of mixing g ". But computations of phase equilibria are now more often done via volumetric equations of state, so it may prove more useful to base stability determinations on fugacities. We develop the necessary relations here and illustrate their application with an example in the following section. We limit the presentation to stability of binary mixtures. 

Once the species present in a solution have been chosen and the values of the various equilibrium constants have been determined to give the best fit to the experimental data, other thermodynamic quantities can be evaluated by use of the usual relations. Thus, the excess molar Gibbs energies can be calculated when the values of the excess chemical potentials have been determined. The molar change of enthalpy on mixing and excess molar entropy can be calculated by the appropriate differentiation of the excess Gibbs energy with respect to temperature. These functions depend upon the temperature dependence of the equilibrium constants. 

S. Krause s thermodynamic treatment of the Gibbs free-energy change of mixing on domain destruction for the whole system of Nc copolymer molecules occupying volume V gives... 

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