Substituent Effect on the Association Phenomenon of an Aqueous Solution of Benzylidene Substituted Aniline at Different Temperatures

Conductivity parameters of an aqueous solution of benzylidene substituted anilines (I-IV) have been determined at five different temperatures in the range of 283.15-318.15 o K, through accurate conductance measurements. The obtained data were analyzed in accordance to Lee-Wheaton equation taking into account the activity of the electrolyte in the solution. The conductance measurement results were used to determine the association constants (KA) of ion-pairs, the mean distance between ions in solution, in addition to the molar conductance at infinite dilution (Λo) for the free ion in the solution. The dependence of (KA) values on the temperature has been examined by plotting Log KA against the reciprocal values of temperature (1/T), which showed linear relationship, where (KA) values decrease with increasing temperature. Moreover, the enthalpy (∆H), Gibbs free energy (∆G) and the entropy (∆S) have been derived from this linear relationship.