Hofmeister Effects in pH Measurements: Role of Added Salt and Co-ions
Date
2003
Authors
Bostrom, Mathias
Craig, Vincent
Albion, Reanna
Williams, David
Ninham, Barry
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American Chemical Society
Abstract
Measurements of pH with a glass electrode that reveal a strong dependence on the ion pair of the background electrolyte and on the salt concentration are presented. Although such phenomena are well known, they are inexplicable in the classical theory based on the Nernst equation. It is shown that this (Hofmeister) effect can be understood once neglected ionic dispersion potentials acting between ions and the glass-water interface are taken into account. At high concentrations, those of interest in biology (≥ 0.1 M), co-ions, are shown to play a profound and previously overlooked role in pH changes near glass-water interfaces.
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Keywords: Cobalt; Electrochemical electrodes; Electrolytes; Glass; Interfaces (materials); Ions; Numerical methods; Sodium chloride; Surface tension; Hofmeister effects; Ionic dispersion potential; Nernst equation; pH measurement; pH effects
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Source
Journal of Physical Chemistry B
Type
Journal article
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2037-12-31
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