Gibbs–Duhem equation

About: Gibbs–Duhem equation is a research topic. Over the lifetime, 393 publications have been published within this topic receiving 6248 citations. The topic is also known as: Gibbs-Duhem equation.

On the gibbs energy and chemical potentials of an ideal gas mixture

Abstract: A b s t r a c t There are three, assentialy independent, derivations of the Gibbs energy of an ideal gas mixture and the chemical potentials of its components. One approach is to flrst derive the expressions for the chemical potentials („i), which are then used in the expression for the molar Gibbs energy G m = P Xi„i, where Xi is the molar concentration of the i-th component in the mixture. In this approach, the molar entropy of the mixture is evaluated a posteriori, as the temperature gradient of the Gibbs energy. The second derivation is the simplest, and is based on the assumed additive decomposition of the Gibbs energy in terms of the partial Gibbs energies of individual components. The third derivation is based on the additive decomposition of the entropy of mixture in terms of partial entropies of its components. The three derivations are here critically examined and discussed.

Mineral Reactions: Equilibrium and Non-Equilibrium Aspects

Abstract: Mineral reactions are a fundamental component of the development of metamorphic rocks but the subject is commonly discussed without reference to deformation which ubiquitously accompanies the chemical processes. In this chapter we concentrate on the coupling between mineral reactions and deformation with particular reference to the controls that processes involved in mineral reactions exert on the development of metamorphic fabrics. Since we are concerned with the processes involved in chemical reactions and the coupling to deformation our emphasis is on systems not on equilibrium. We first discuss the conditions for coexisting minerals to be at chemical equilibrium during deformation and the controls on the position of the equilibrium phase boundary during deformation and diffusion. We then proceed to discuss the behaviour of chemical systems not at equilibrium and the roles of non-equilibrium stationary states; we consider the evolution of chemical systems to non-equilibrium stationary states driven by the Ross excess work instead of differences in the Gibbs energy which drive systems to an equilibrium stationary state. The fundamental importance of processes associated with the nucleation and growth of new mineral grains during deformation is emphasised particularly the isochoric replacement of old grains by new ones, the role of stress-assisted mass transfer (‘pressure solution’) and the significance of networked chemical reactions. Chemical dissipation is discussed in terms of the Prigogine principle of minimum entropy production.