Organizations & People
Pure Appl. Chem.,
Vol. 70, No. 7, pp.1419-1422, 1998
COMMISSION ON ELECTROANALYTICAL CHEMISTRY
in Non-Aqueous and Mixed Solvents: Predicting
pH(PS) of Potassium
Hydrogen Phthalate for Alcohol-Water Mixtures
Rondinini, P. R. Mussini, T.
Mussini, and A. Vertova
equations for estimating pH(PS) (PS = Primary Standard) of the potassium
hydrogen phthalate buffer in any aqueous-alcoholic mixture are given
as functions of the alcoholic moiety mole fraction, x, in the
mixture and of the relative permittivity, e , and the autoprotolysis constant, pKap,
of the pure alcohol at 298.15 K. The two equations, one valid for 298.15
K and the other covering the 263 - 318
K temperature range, have been optimized by using the experimental data
of pH(PS) in aqueous mixtures with the following alcohols: methanol,
ethanol, propan-2-ol, ethane-1,2-diol, 2-methoxyethanol ("methylcellosol
ve"). The equations, tested on subsets generated from the full-set
by removing an entire co-solvent at a time, provide predicted pH(PS)
values which differ from the "true" ones by less than 0.1
pH over the entire range of co-solvent composition: 0<x<0.75.
The predictive equations are recommended for calculating pH(PS) only
in those aqueous-alcoholic media for which the corresponding experimental
values are not available, and not as smoothing equations for water and
its mixtures with the above-mentioned solvents.
Page last modified 23 January 1999.
Copyright ©1997, 98, 99 International Union of Pure and Applied Chemistry.
Questions or comments about IUPAC, please contact, the Secretariat.
Questions regarding the website, please contact web