NEW APPROACH TO SENSITIVITY ANALYSIS OF MULTIPLE EQUILIBRIA IN SOLUTIONS

Citation
I. Fishtik et al., NEW APPROACH TO SENSITIVITY ANALYSIS OF MULTIPLE EQUILIBRIA IN SOLUTIONS, Journal of the Chemical Society. Faraday transactions, 90(21), 1994, pp. 3245-3252
Citations number
20
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
ISSN journal
09565000
Volume
90
Issue
21
Year of publication
1994
Pages
3245 - 3252
Database
ISI
SICI code
0956-5000(1994)90:21<3245:NATSAO>2.0.ZU;2-B
Abstract
We consider multiple equilibria in solutions in which the interaction of n chemical species is described by means of m stoichiometrically in dependent reactions (SIRs). For the study of certain thermodynamic pro perties of such systems, in particular, for sensitivity analysis, it i s important to know the determinant DELTA of the Hessian matrix of the Gibbs energy, as a function of the extent of the SIRs. Any linear com bination of SIRs, in which (at least) m - 1 species are not involved, is called a Hessian response reaction (HR): Several properties of the HRs are pointed out, in particular, the equivalence of DELTA to the su m of contributions originating from each HR. The effect of temperature and pressure on chemical equilibria in ideal solutions is analysed. I t is shown that the sensitivity coefficient of a chemical species A(i) may be presented as a sum of contributions coming from all HRs in whi ch A(i) is involved. Each of these contributions is a product of the s toichiometric coefficient of A(i), the enthalpy or volume change of th e respective HR, and a concentration-dependent term which is always po sitive. It is also shown that the relaxation contribution to the heat capacity is a sum of contributions over all HRs.