A note on “ The significance of the electrode potential

In a recent paper* bearing the above title, Dr. Heyrovsky attempts to elucidate the factors determining electrode potentials by means of a thermodynamical argument based on a cyclic process involving the following steps :— (1) One gramme molecule of the metal vapour is withdrawn at the vapour pressure of the metal and ionized into metal ions and electrons. (2) One gramme molecule of water vapour is ionised into H‘ and OH' ions. (3) The Me+ ions are allowed to combine with the OH' ions to form MeOH. (4) The MeOH formed and the H· are transferred into the solution and the electrons remaining in stage (1) are condensed into platinum and returned to the metal. (5) The MeOH dissociates in solution into Me+ and OH' ions (hydrated) and the metal ions are transferred to the metal against the electrode potential π, thus completing the cycle.