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Dynamic modeling of ph electrodes
Author(s) -
Hershkovitch Hugo Z.,
Mcavoy Thomas J.,
Liapis Athanasios I.
Publication year - 1978
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450560312
Subject(s) - electrode , transient (computer programming) , glass electrode , ionic bonding , transient response , salt (chemistry) , chemistry , reference electrode , materials science , mechanics , chemical physics , analytical chemistry (journal) , thermodynamics , ion , inorganic chemistry , electrolyte , computer science , chromatography , physics , engineering , electrical engineering , organic chemistry , operating system
A mathematical model for the dynamic behavior of the pH glass electrode is presented. The model results from a description of ionic transport in an assumed stagnant boundary layer around the electrode surface. Documented information regarding the characteristics and operation of the glass electrode and the mechanism of pH measurements is combined with dynamic mass balances in an attempt to describe its transient response. New experimental results are presented which indicate both the validity of the model and that double layer effects are also contributors to the dynamic response. One of the interesting features of the model is that it predicts that if an electrode is subjected to a step change from a solution of a strong acid at a given pH to another solution of the same acid at the same pH but containing a salt of that acid, a transient response will result. This effect has been observed experimentally and is due to the differences in the diffusivities of the various ionic species present in the solutions.