Rafidain Journal of Science

Abstract

This paper traces the conductivity of diclofenac potassium salts in the low concentrations in water and mixtures of water and methanol (10%, 20% and 30% aqueous methanol) at different temperatures (288.15, 293.15, 298.15, 303.15 and 308.15 K). The conductivity data were analyzed using the Lee-Wheaton conductivity equation to obtain the values ​​of equivalent conductivity at infinite dilution “∧o”, association constants (K_A), the association diameter (R) and Walden product (Λ₀η₀). The results showed that diclofenac potassium salt behaves as weak electrolytes in the solvents used. Moreover, standard thermodynamic parameters of the association (change value in: Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were calculated and discussed. The results showed that the values ​​of molar conductivity, the distance parameter between the ions (R) and association constants (KA) increase with increasing temperature at the best fit value of the standard deviation (σ). The thermodynamic results also indicated that the ion association process is endothermic (+ΔH) and spontaneous (- ΔG) and increasing degrees of freedom (+ΔS).