Medium Effects and Determination of Primary and Secondary Standards for pH Measurements in (Glycerol + Water) Solvent Media at Normal and Subzero Temperatures, With Characterization of Appropriate Salt Bridges

Abstract

The primary and the secondary standards for the pH measurements in solvent media Z = (glycerol [G] + water [W]) at glycerol mass fractions wG up to 0.4 and at temperatures from −10 °C to +40 °C have been determined in compliance with the IUPAC criteria. To this purpose, Harned’s reversible cell {Pt|H2|Primary Buffer + KCl in Z|AgCl|Ag|Pt} and Baucke’s nonreversible cell {Pt|H2|Buffer at pHPS in Z|Salt Bridge in Z|Buffer at pHSS in Z|H2|Pt} were used, respectively. As a result, three primary standards (based on the “carbonate”, the “equimolal phosphate”, and the “phthalate” buffers) and three secondary standards (based on the “tetroxalate”, the “tartrate”, and the “unequimolal phosphate” buffers) are now available. Their internal consistency was ascertained through the linear pH dependence of the voltage of the cell {Pt|H2 |Buffer at pHPS [or pHSS] in Z|NH4Cl Bridge in Z|Reference Electrode}. These acquisitions enable the user to perform routine pHX measurements by the regular operational cell {Reference E...