Revista de Química e Engenharia Química Aplicada

Formulation of Simple Electrolytic Redox Systems According to GATES/GEB Principles

Anna Maria Michałowska-Kaczmarczyk, Aneta Spórna-Kucab, Tadeusz Michałowski

The linear combination f12 = 2∙f(O) – f(H) of elemental balances: f1 = f(H) for H, and f2 = f(O) for O is the basis to formulate the generalized electron balance (GEB) for electrolytic redox systems according to Approach II to GEB, realized within the generalized approach to electrolytic systems (GATES) as GATES/GEB. Together with charge balance (f0 = ChB) and K–2 elemental/core balances: f3,…,fK, the f12 completes the set of K balances needed for resolution of an electrolytic redox system, of any degree of complexity. For a nonredox system, a proper linear combination of f12 with f0, and fk = f(Yk) (Yk ≠ H, O; k=3,…,K) gives the identity, 0 = 0. Consequently, in nonredox systems, f12 is linearly dependent on f0,f3,…,fK, i.e., f12 is not the independent balance. This independency/dependency property of f12 distinguishes between redox and non-redox systems. In a redox system, a proper linear combination of f12+f0 with the balances for electron-non-active elements/cores gives the simpler form of GEB, where the species composed only of electron-non-active elements are not involved. The multipliers applied in the linear combinations are equal to the oxidation numbers for elements participating redox or non-redox system. This regularity is highly important in context of the fact that the ‘oxidation number’ was essentially a contractual concept. Within GATES/GEB, the terms: oxidation number, oxidant and reductant, stoichiometry, and equivalent mass are derivative/redundant concepts only; the roles of oxidants and reductants are not assigned a priori to individual components. All these concepts are illustrated on simple examples of redox D+T systems, with aqueous solutions of (S1) Br2, and (S2) HBrO as titrand D, and NaOH solution as titrant T.