Enthalpy of mixing of 1:1 electrolytic solutions at varying ionic strength at 298.15 K in water + l,4-dioxane mixed solvent system

467-472Enthalpy of mixing for six possible combinations of solutions of NaCl, KCl, NaBr and KBr have been determined as a function of ionic strength. The experiments have been performed at constant ionic strengths of 1.0 and 2.0 mol kg-1 at 298.15 K using LKB now microcalorimeter in water +1,4-dioxane mixed solvent system. Data differ appreciably from corresponding data in water and even do not support Young's Cross Square Rule. Pitzer ion-interaction model is utilized to obtain binary and triplet interaction parameters i.e. ΘN and ΨNX .The data suggest that deviation from Young Cross Square Rule may arise from preferential solvation of the ions and ion clusters, as organic cosolvent is also incorporated in the solvation shell.