The Absolute Potential of a Standard Hydrogen Electrode I.Theoretical Induction of pH=(⊿E-⊿Er)/0.059 II.Absolute Scale of Ionic Tendency III.Solution of Metallic Mercury in Water

摘要

I.A potential of a half-cell has neither been obtained by calculation nor experimental. Only a relative potential can be obtained, as compared with a potential of a standard hydrogen electrode (S. H. E.) which is assumed to have value of zero at 25℃. However the present author obtains the absolute potential of a S. H. E. to be -0.059 V experimentally and theoretically. Generally speaking, a current of a half-cell seems to be caused by flow of electrons which appear in an oxidation reaction M+aH+→Ma+ +aH++ae-. Therefore the potentials of Pt|H+ (1m)|H||H+(nm)|Pt,⊿E are pro-portional to the evolved volumes of hydrogen of n mol which is proportional to the concentrations of H+ in solution, from which the equation ⊿E=2.303RT・log[H+]n/[H+]1=-0.059・log10n/101=-0.059・{-pHn-1} is derived. That is, pH=⊿E/0.059-0.059=(⊿E-⊿Er)/0.059, where ⊿Er is an absolute potential of a reference cell. II.The ionic tendency means the order of their tendency to lose electrons to from positive ions. The scale of ionic tendency is previously shown by electromotive against a S.H.E. Pt|H|H+(1m) which is assumed to be 0.00V. Therefore, the ionic tendency of the more electropositive metal than hydrogen is negative, but that of the less electropositive one is positive. When a half-cell Pt|H+(0m) which has the absolute zero volt is used as reference cell, the electromotives are always negative, that is, the ionic tendencies for every metal are negative. III.A potential of a half-cell is caused by reaction M+aH+→Ma++aH++ae-. It means that every metal can react with proton H+, even as H+ which comes from H2O(⇄H++OH-). That is, every metal can be dissolved by water.