Abstract
The buffer capacity concept is extended on dynamic redox systems, realized according to titrimetric mode, where changes in pH are accompanied by changes in potential E values; it is the basic novelty of this paper. Two examples of monotonic course of the related curves of potential E vs. and pH vs. Φ relationships were considered. The systems were modeled according to GATES/GEB principles.
Highlights
The buffer capacity concept is usually referred to as a measure of resistance of a solution (D) on pH change, affected by an acid or base, added as a titrant T, i.e., according to titrimetric mode; in this case, D is termed as titrand
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/generalized electron balance (GEB)), described in details in [5,6,7,8,9,10,11,12,13,14,15,16], and in references to other authors'
C0 = C + C 2 ⋅10 pK 1 be principally related to monotonic functions. This concept looks awkwardly for non-monotonic functions pH=pH(Φ) and/or E=E(Φ) specified above (2o–4o) and exemplified in Figures 7-9 presented in Appendix 3
Summary
The buffer capacity concept is usually referred to as a measure of resistance of a solution (D) on pH change, affected by an acid or base, added as a titrant T, i.e., according to titrimetric mode; in this case, D is termed as titrand. We refer to the disproportionating systems: (S1) NaOH ⇒ HIO and (S2) HCl ⇒ NaIO, characterized by monotonic changes of pH and E values during the related titrations (i.e., the case 1o). In both instances, the values: V0=100, C0=0.01, and C=0.1 were assumed. Referring to dynamic redox systems represented by titration curves presented in Figures 1 and 2, we plot the relationships: βV vs Φ, βV vs pH, βV vs E, and βEV vs Φ, βEV vs pH, βEV vs E for the systems: (S1) NaOH ⇒ HIO; (S2) HCl ⇒ NaIO. ΒV vs. Φ, (B) βV vs. pH, (C) βV vs. E and (D) βEV vs. Φ, (E) βEV vs. pH, (F) βEV vs. E are plotted in Figures 3 and 4
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