“Why Not Stoichiometry” versus “Stoichiometry—Why Not?” Part III: Extension of GATES/GEB on Complex Dynamic Redox Systems

Abstract

In the third part of a series of articles issued under a common title, some examples of complex dynamic redox systems are presented and considered from analytical and physico-chemical viewpoints; the analysis is a leitmotiv for detailed, physico-chemical considerations. All attainable physico-chemical knowledge is involved in algorithms applied for resolution of the systems, realized with use of iterative computer programs. The first redox system (System I) is related to titration of FeSO4 + H2C2O4 with KMnO4 solution in acidic (H2SO4) medium, where simultaneous determination of both analytes from a single curve of potentiometric titration is possible. The possibility of the formation of precipitates (FeC2O4 and/or MnC2O4) in this system is taken into considerations. The second system (System II) relates to the complete analytical procedure involved in the iodometric determination of Cu; four consecutive steps of this analysis are considered. As a reasonable tool for explanation of processes occurring during simulated redox titration, speciation diagrams are suggested. This explanation is based on graphical presentation of results obtained from the calculations. The calculations made for this purpose are performed in accordance with principles of the generalized approach to electrolytic systems (GATES) with generalized electron balance (GEB) or GATES/GEB and realized with use of iterative computer programs offered by MATLAB. The reactions proceeding in this system can be formulated, together with their efficiencies, at any stage of the titration. Stoichiometry is considered as the derivative concept when put in context with GATES/GEB. The article illustrates the enormous possibilities and advantages offered by GATES/GEB.

Principles of Titrimetric Analyses According to Generalized Approach to Electrolytic Systems (GATES)

“…[21]. Other examples of high degree of complexity are shown in the works [9,11,12,[14][15][16]. One of the examples in Ref.…”

“…One of the examples in Ref. [12] concerns a four-step analytical process with the four kinds of reactions, involving three electroactive elements.…”

“…The detailed considerations in this chapter are based on principles of the generalized approach to electrolytic systems (GATES), formulated by Michałowski [9] and presented recently in a series of papers, related to redox [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] and nonredox systems [27][28][29][30][31][32] in aqueous and in mixed-solvent media [33][34][35][36][37]. The closed system separated from its environment by diathermal walls secure a heat exchange between the system and its environment, and realize dynamic processes in a quasistatic manner under isothermal conditions.…”

Solubility and Dissolution in Terms of Generalized Approach to Electrolytic Systems Principles

“…General Remarks The system considered in this section is related to iodometric, indirect analysis of an acidified (H 2 SO 4 ) solution of CuSO 4 [33]. On the preparatory step, an excess of H 2 SO 4 is neutralized with NH 3 until a blue colour appears, which is derived from ( )…”

Dynamic Buffer Capacities in Redox Systems

“…The redox systems with one, two or more electron-active elements are modeled according to principles of Generalized Approach to Electrolytic Systems with Generalized Electron Balance involved (GATES/GEB), described in details in [5][6][7][8][9][10][11][12][13][14][15][16], and in references to other authors' papers cited therein.…”