Dissociation Constant Studies of 2-Substituted 4-Formylbenzoic Acid based on Conductometric Parameters using Fuoss-Hsia Theories

The dissociation constant is a quantitative measure of the strength of an acid in solution. This study examines dissociation constant for the series substituted acids like Ortho-alkoxy-4-formylbenzoic acid. The use of (2-methoxy ethanol) as a solvent contributed to the study expected to form free ions or solvent separated ion pair which has been studied with the use conductometric method at different temperatures ranged from 293.15 to 318.15K. The study aims at figuring out dissociation constant, equivalent conductance at infinity dilution, and Walden product by minimization technique using Fuoss-Hsia for both (Modified and Complete) equations. It has been found in the results that the calculated values based on statistical sum square (different between practical and theoretical values) is equivalent conductance at infinity dilution and dissociation constant. It has also been observed that increase the temperature leads to the increase of the molar conductance at infinity dilution, and the increase in association. Moreover, the substituted alkoxy group also affected dissociation of compounds. In this study, the thermodynamic parameters (Delta H degrees,Delta G degrees and Delta S degrees) have also been evaluated and discussed. Finally, the effect of substituent groups on rate of dissociation was studied and explained with agreement to the principles of mesomeric(M) and Inductive effect(I) of substituent groups on dissociation constant.