THERMODYNAMIC EQUILIBRIUM OF NONHOMOGENEOUS AND NONISOTROPIC CHEMICALLY REACTIVE SYSTEMS

Abstract

Thermodynamic equilibrium conditions for nonhomogeneous and nonisotropic chemically reactive systems are developed. In a preliminary discussion it is shown that the fundamental equilibrium criteria are the constancy of the temperature and of the generalized chemical potentials, and that these are the only independent equilibrium criteria in the absence of a chemical reaction. The main result is the mechanical equilibrium criterion for this general case, in which a weighted average of the stress tensor components replaces the hydrostatic pressure of simple fluids. This criterion is compared with the mechanical equilibrium condition which is derived from Newton's laws and the implications of this comparison for simple fluids and for elastic systems are discussed. The equilibrium constant for a chemical reaction is independent of the nonisotropy and nonhomogeneity of the system.

KEYWORDS:

• Equilibrium
• Nonisotropy