Conductometric studies on solvation behaviour of citric acid in water + methanol and water + ethanol mixtures at different temperatures

Abstract

The paper reports the study on the effect of solvation of the species of citric acid in water + methanol and water + ethanol mixtures (<i style="">v/v</i>) on its conductivity behaviour as a function of temperature. The specific conductance was measured in the temperature range 283-313 K and the evaluated equivalent conductance was analyzed by Kraus-Bray and Shedlovsky models of conductivity. Limiting molar conductance (λ⁰_m), dissociation constant (<i style="">K</i>_C) and association constant (<i style="">K</i>_a) were evaluated for all solvent compositions. The limiting molar conductance was found to decrease with the increase in amount of co-solvent to water. <i style="">K</i>_c increased with increase in temperature till 60% methanol and 40% ethanol with a later decrease. Fuoss Accascina equation was applied and it was proved that the formation of ion pairs and scanty amount of ion triplets takes place in the system. Walden product, corrected Stokes radius (r_i), thermodynamic parameters and solvation number also have been evaluated. Born relation of solvation was verified. These data were used to study the nature of ion-solvent and solvent-solvent interactions existing in the system under prevailing conditions.