p<i>K</i> Determination. A Mean Field, Poisson−Boltzmann Approach
Agostinho NetoAugusto
Drigo FilhoElso
FosseyMarcelo Andres
Ruggiero NetoJoão
1999
A model describing dissociation of monoprotonic acid and a method for the determination of its p<i>K</i> value are
presented. The model is based on a mean field approximation. The Poisson−Boltzmann equation, adopting
spherical symmetry, is numerically solved, and the solution of its linearized form is written. By use of the pH
values of a dilution experiment of galacturonic acid as the entry data, the proposed method allowed estimation
of the value of p<i>K</i> = 3.25 at a temperature of 25 °C. Values for the complex dimensions and dissociation
degree are calculated using experimental pH values for solution concentration values ranging from 0.1 to 60
mM. The present analysis leads to the conclusion that the Poisson−Boltzmann equation or its linear form is
equally suited for the description of such systems.