Abstract:

To transform the scale of redox titration for a unified formula of the titration scale, a relative concentration of the aqueous electron $ {{R}}_{{\text{e}}^{{-}}} $ is proposed, and a new theory for redox titration is then developed with $ \text{p}{{R}}_{{\text{e}}^{{-}}} $ as its monitoring scale. This new theory addresses the balancing of the semi-redox-reaction, provides the general formula for calculating $ \text{p}{{R}}_{{\text{e}}^{{-}}} $, investigates the general variation of $ \text{p}{{R}}_{{\text{e}}^{{-}}} $ in titration, and reintroduces the principle of an electron indicator. In this study, the titration of Ce⁴⁺ to Fe³⁺ solution is used as an example to deduce the following aspects: the approach for drawing titration curves, calculation for titration jump ranges, and criterion of direct and accurate titrations. Finally, the effect of $ {{K}}_{\tau }^{{\rm{ \mathsf{ ϴ} }}{ʹ}}, $which is the conditional equilibrium constant of a redox reaction, on titrimetric analysis is discussed.

Key words: Redox titration, Relative concentration of aqueous electron, Titration curve, Electron indicator, Accurate titration