The Protoelectric Potential Map ( PPM): An Absolute Two- Dimensional Chemical Potential Scale for a Global Understanding of Chemistry

We introduce the protoelectric potential map (PPM) as a novel, two-dimensional plot of the absolute reduction potential (pe(abs) scale) combined with the absolute protochemical potential (BrOnsted acidity: pH(abs) scale). The validity of this thermodynamically derived PPM is solvent-independent due to the scale zero points, which were chosen as the ideal electron gas and the ideal proton gas at standard conditions. To tie a chemical environment to these reference states, the standard Gibbs energies for the transfer of the gaseous electrons/protons to the medium are needed as anchor points. Thereby, the thermodynamics of any redox, acid-base or combined system in any medium can be related to any other, resulting in a predictability of reactions even over different media or phase boundaries. Instruction is given on how to construct the PPM from the anchor points derived and tabulated with this work. Since efforts to establish absolute reduction potential scales and also absolute pH scales already exist, a short review in this field is given and brought into relation to the PPM. Some comments on the electrochemical validation and realization conclude this concept article.