The Determination of Oxidation-Reduction Potentials from Equilibrium Data

The determination of the oxidation-reduction potentials is more reliable from equilibrium data than from electromotive force data. The potential of the ferric-ferrous electrode was calculated from the experimentally determined equilibrium constant of the reaction: 2Fe (ClO4)3 +2Hg⇔ 2Fe (ClO4)2+Hg2 (ClO4)2 The perchlorates, mercury, and perchloric acid are better suited for the determination of the equilibrium constant than the nitrates, silver and nitric acid employed by A. A. Noyes and Braun (J. Arn. Chem. Soc. 34, 1016, 1912). The true equilibrium constant of the reaction was determined by suitable experimental procedure and subsequent mathematical and graphical analysis