A unified pH scale for all solvents: part I – intention and reasoning (IUPAC Technical Report)

Abstract

The definition of pH, its measurement and standard buffers, is well developed in aqueous solutions. Its definition in solvents other than water has been elaborated for a couple of solvents and their mixtures with water. However, the definition of a universal pH scale spanning all solvents and phases, not to mention standard procedures of measurement, is still a largely uncharted territory. UnipHied is a European collaboration and has the goal of putting the theoretical concept of an earlier introduced (2010) unified pHabs scale on a metrologically well-founded basis into practice. The pHabs scale enables the comparability of acidity between different phases. This article draws the connection of the concepts of unified acidity and secondary pH measurement.

Electrochemistry and Reactivity of Chelation‐stabilized Hypervalent Bromine(III) Compounds

“…The term “ ” stands for unified pH (pH abs ) “aligned” with the aqueous pH scale, that is, the values in any solvent are directly comparable with the conventional aqueous pH values. In other words, in a solution with a given , made in any solvent, the chemical potential of the solvated proton is equal to the chemical potential of solvated proton in water at the same value of conventional pH [37] …”

“…In other words, in a solution with a given pH H 2 O abs , made in any solvent, the chemical potential of the solvated proton is equal to the chemical potential of solvated proton in water at the same value of conventional pH. [37] The acidity necessary for protonation of 2 a is expressed as "buffer point pH H 2 O abs ", that is, pH H 2 O abs , at which approximately half of 2 a is free and half has TfOH added (2 a-TfOH, Figure 6A). Experiments for determination of the buffer point were carried out in 1,2-dichloroethane, where a self-consistent acidity scale has been previously established and linked to the unified pH (pH H 2 O abs ) scale.…”

Effects of Process and Formulation Parameters on Submicron Polymeric Particles Produced by a Rapid Emulsion-Diffusion Method

“…However, this definition cannot be applied using organic solvents and their mixtures with water and other polymers. In this regard, there is still a largely uncharted territory about these complex systems [41].…”

The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions

“…[13,14] These very particular states also imply that the particles do not interact with each other and are thus clearly hypothetical as well. Yet, they are well defined [15] and essentially refer to the same states as considering an isolated particle in vacuum and thus relate to gas phase thermodynamics, i. e., IE, EA, GA and GB. [16,17] In addition and following Bartmess, [17] contributions to enthalpy and entropy are added to connect the gaseous reference state to the recommended standard conditions in thermochemistry and electrochemistry (10 5 Pa and 298.15 K).…”

“…For the proton we use the value Δ solv G °(H + , H 2 O) = −1104.5 kJ mol −1 [22] . For a more detailed description of these scales and their connection to standard states, we refer to the literature [13−15,23] . The individual values constituting these scales are, of course, based on the (single ion) Gibbs solvation energy or the Gibbs transfer energy.…”