Author:
Max Jean-Joseph,Chapados Camille
Abstract
The titration of NaOH by HCl is achieved through infrared spectral measurement of the various mixtures. Factor Analysis (FA) is used to separate the spectra. Four principal spectra were necessary to perform the analysis: pure water, 2.09 M HCl, 2.23 M NaOH, and 2.60 M NaCl solvated water. Each of the 18 experimental spectra obtained was determined to be a linear combination of these principal spectra. The composition of the solutions retrieved from the IR analysis is identical to what was determined by the mass balance. The mean activity coefficient of HCl was calculated using the concentration of HCl obtained by IR and the activity obtained by pH measurements. It was found that the mean activity coefficient increased by a factor greater than 2 in the presence of 1 M NaCl. Because the water molecules associated to the ionic pair H+/Cl-, as observed by IR, are unmodified by the presence of the salt, such an increase cannot be attributed to a modification of the strong association of the water molecules to the pair of ions.Key words: infrared spectroscopy; ATR; liquid; acidic solutions; alkaline solutions; aqueous solutions; factor analysis; principal spectra; HCl-, NaOH-, NaCl-solvated water; activity coefficient; IR titration.
Publisher
Canadian Science Publishing
Subject
Organic Chemistry,General Chemistry,Catalysis
Cited by
32 articles.
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