The Relation between the Standard Potentials of Metal Electrodes and the Standard Potentials of Redox Electrodes Formed By Metal Ions

Abstract

The Relation between the Standard Potentials of Metal Electrodes and the Standard Potentials of Redox Electrodes Formed by Metal Ions A.I. Chernomorskii Scientific Resources Co. e-mail: SciResources@aol.com The standard potential of redox electrodes Eo Men+/Mem+ are defined by the standard potential of corresponded metal electrodes Eo Men+/Me and Eo Mem+/Me by the Luter equation1. It is of interest to compare the differences of the standard potentials of metal electrodes Eo Men+/Me - Eo Mem+/Me (for example, Eo Fe3+/Fe - Eo Fe2+/Fe) and the standard potentials of corresponded redox pairs Eo Men+/Mem+ (for example, Eo Fe3+/Fe2+). It can be seen that the points are spread by both sides from one center in Eo Men+/Me - Eo Mem+/Me , Eo Men+/Me m+ - coordinates. The least differences Eo Men+/Me - Eo Mem+/Me correspond to redox pairs with standard potentials close to ~+0.5 V SHE in this center (Fig 1). The differences Eo Men+/Me - Eo Mem+/Me bring in the definite deposits in activity of redox pairs Eo Men+/Me m+. For one metal, the electron deposits in Eo Men+/Me and Eo Mem+/Me should compensated in the difference Eo Men+/Me - Eo Mem+/Me. Hence, the differences Eo Men+/Me - Eo Mem+/Me should define the ionic deposits in activity of redox pairs2,3. When the difference Eo Men+/Me - Eo Mem+/Me → 0, the chemical activity of redox pairs should also approach to zero. The less differences Eo Ru4+/Ru - Eo Ru3+/Ru = 0.03 V and Eo Ru3+/Ru - Eo Ru2+/Ru = 0.07 V correspond to Eo Ru4+/Ru 3+ = 0.49 V SHE and Eo Ru3+/Ru 2+ = 0.249 V SHE (Fig.1). In this center, the positive differences Eo Men+/Me - Eo Mem+/Me correspond to redox pairs with unstable more oxidizing ions (Te4+/Te2+; Po4+/Po2+; Ru4+/Ru3+). The negative differences Eo Men+/Me - Eo Mem+/Me correspond to redox pairs with stable less oxidizing ions (Ru3+/Ru2+; Po3+/Po2+). It can be drawn the line between the points correspondent to these redox pairs formed by ions of non-active metals (Ru,Cu) and metals (Te, Po) transition from metals to non-metals. This line intersects the Eo Men+/Mem+ - axis (when Eo Men+/Me - Eo Mem+/Me = 0) at Eo Men+/Mem+ = ~ +0.47 V SHE (Fig.1).