Multicomponent Bodies and Mixtures

Independent variables of functions are extended to account for the effects of composition in the case of mixtures; chemical reactions are also included. Entropy inequality is applied on the basic mixture model and chemical reactions are shown to cause non-equilibrium behaviour. The equilibrium in a chemically reacting mixture is analysed. The chemical potentials are introduced and their role as descriptors of compositional effects is stressed. A more general concept of partial quantities is then presented. The analysis of mixtures is developed on the basis of both Helmholtz and Gibbs energies and in both specific and molar quantities. The consequences of reaction stoichiometry are explained, and the extent of the reaction and the reaction Helmholtz and Gibbs energies are introduced. Finally, the basic model of a multiphase body is described, and the criteria of the phase equilibrium are derived.