Temperature dependence of Ion Association of Tetra Aqua (1 , 10 – phenathroline) Nickel (II) Chloride in Ethanol –Water mixture

Abstract

The ion association constant (KA) of [Ni(1,10 phenathroline )(H2O)4] Cl2 , has been determined by conductivity measurements at 278.15-318.15 K . it is found that the order of magnitude of KA at any temperature at different percentage of ethanol – water mixture decrease with decreasing ethanol percentage and increasing the temperature .The enthalpy, gibs free energy and entropy increase with increasing ethanol percentage and temperature, this can be attributed to the decrease in the fraction of the contact ion pairs formed by the hydrogen bonding between the polar hydrogen of the complex and solvent atoms . The data were analyzed using Lee – Wheaton equation to calculate: (Λo, KA & R) equivalent conductance Λo , association constant KA and the main distance between ion in solution R .Walden product (Λo ηo) have also been calculated for each solvent composition , a relationship was found to exist between the (Λo ηo) and 1/D of the medium which indicate the tendency of the association of ions.