Re-examination of the Pka1 and Pka2 values of adipic acid in water 25oC.
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Date
2012-05-15
Authors
Mundia, Kamau Patrick
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Abstract
Adipic acid and its derivatives have long been
used In the manufacture of nylon 6.6, explosives and as a
food additive. In spite of its age-long use it was
surprising to note that a variety of different values have
been reported in the chemical literature for the two
dissociation constants of the acid.
It was therefore found both desirable and
interesting to investigate the reason(s) for this discrepancy
and to determine the precise pKal and pKa2 values in aqueous
solutions at 250C. Accordingly pH titration method was used
and solutions of adipic acid in the concentration range
O.0025M to O.0200M were titrated against KOH solutions. It
was found as expected. that pKal and pKa2 values varied with
tne concentration. The values so obtained were extrapolated
to zero concentration which yielded the two dissociation
constants as 4.43258 and 5.63552.
All calculations for these pKa values were carried
out on a DV-ERGO personal computer and the analysis of the
data led to the realization that the literature values
corresponded to specific concentrations and are not at
infinite dilution.
Description
The QD 142. M8
Keywords
Water --Analysis//Water --Composition