UNNOTICED IDENTITIES IN CHEMICAL THERMODYNAMICS

General homogeneous chemical systems at thermodynamic equilibrium have been considered, in which an arbitrary number of reactions takes place, and in which ideal behaviour of the reacting species is not assumed. Also in this general case, the Hessian response equilibria (see Fishtik st al., J. Chem. Sec., Faraday Trans., 1994, 90, 3245) play a central role in the study of the Hessian determinant (the determinant of the matrix of the second derivatives of the Gibbs energy with respect to the extents of the reactions), as well as in the analysis of the sensitivity coefficients. Both quantities may be presented as sums of contributions associated with Hessian response equilibria and pairs of Hessian response equilibria.