DETERMINATION OF THE MOLALITY SCALE DISSOCIATION-CONSTANTS OF ACETIC-ACID IN AQUEOUS SODIUM-CHLORIDE SOLUTIONS AT 298.15 K

Equations are presented for the calculation of the molality scale dissociation constants (i.e. the K-m values) of acetic acid in aqueous solutions at 298.15 K. These equations apply when the ionic strength of the acetic acid solutions has been adjusted by NaCl. The K-m value for a certain ionic strength can be calculated from the thermodynamic dissociation constant by means of formulas for ionic activity coefficients. The ionic activity coefficient formulas used in this study originate from Debye-Huckel theory. The experimental data used in the parameter estimation and in the tests of the resulting equations were mainly taken from the literature. In these data were included results of measurements on galvanic cells without a liquid junction and on conductivity cells. New experimental data used in the tests were obtained by potentiometric titrations. For these titrations, a recently developed method was used to estimate the correction for the imperfections existing in glass electrode cells including the unknown liquid junction potentials. It is shown that almost all data used in the tests can be interpreted within experimental error by means of the model used. These data include salt molalities up to 3.0 mol kg(-1) and acetic acid molalities up to 5.4 mol kg(-1).