Gibbs energy of a mixture

Analogous to the defining equation for the residual Gibbs energy of a mixture, G G — G , is tne definition of a partial molar residual Gibbs energy ... 

Although generally used for pure fluids, Equation (4.307) is sometimes also used to find the fugacity of a mixture, (() , =fjp- The fugacity of a mixture is just an altered representation of the Gibbs energy of a mixture, RT nf = g- g. ... 

These definitions are also valid for mixtures, provided the values of U, H, and 5-used are those for the mixture. That is. the Helmholtz and Gibbs energies of a mixture bear the same relation to the mixture internal energy, enthalpy, and entropy as the pure component Gibbs energies do to the pure component internal energy, enthalpy, and entropy. 

Analyzing the Gibbs Energy of a Mixture to Detennine Whether It Is an Ideal Mixture... 

The Gibbs energy of a mixture of two enantiomorphs (optical isomers of the same substance) is given by... 

C0U] High temperature calorimetry, integral Gibbs energy of a mixture 1050°C, y phase < 33 at.% Cu, < 33 at.% Fe... 

On further cooling, the tangent breaks away from the liquid curve and becomes a straight line below the liquid curve, giving the Gibbs energy of a mixture of diopside and anorthite crystals just as in the section at T. The difference is that now it is completely below the liquid curve, and therefore a mixture of crystals is the stable configuration of the system. 

When the excess molar volume and entropy are set equal to zero, the model describes what is called a regular solution. The excess molar Gibbs energy of a mixture is = + pVm m- Using the expression of Eq. 11.1.31 with the further assumptions that and 5 are zero, this model predicts the excess molar Gibbs energy is given by... 

Discuss the relationships among chemical potential, activity and the Gibbs energy of a mixture. 

This equation relates the Gibbs energy of a mixture of substances to the amounts and chemical potentials of those substances. As argued above for GnvA/ the chemical potential p.A relates the change in G to a change in the amount of substance A. 

Our interest in chemical potentials (and activities) arises from the fact that the Gibbs energy of a mixture can be expressed in terms of the amounts of the substances and their chemical potentials, as shown by equations (13.31) and (13.32). These two equations, and the second law of thermodynamics, can be used to develop the criterion for predicting the direction of spontaneous chemical change. 

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