Standard potential and chemical solvation energy of an electron in ethylenediamine

Abstract

Potential sweep and cyclic voltammetry was carried out in ethylenediamine solutions of LiCl, LiI, NaI, KI and CsI. In all of the solutions electrolytic generation of solvated electrons was confirmed by the observation of a blue cloud formation around a tungsten electrode at potentials where a sharp increase in cathodic current occurred. From the Tafel plots of the cathodic currents, the electrode reaction schemes for the respective salt solutions were described in terms of the solvated electron species: free solvated electron e − s , ion-pair M + · e − s and alkali anion M −. Taking account of the solute equilibria, the standard potential of e − s was found to be −2.57 ± 0.01 V referred to the E 1 2 value of bis(biphenyl)chromium(I). From an extra-thermodynamic assumption with this potential value, the chemical solvation energy of e − s in ethylenediamine was determined as −1.31 eV.