Abstract
The present work deals with studying the effect of solvent and temperature on the solvolysis process using both the pH-metric and the conductometric measurements. The pH and the conductivity of different concentrations of the phenyl hydrazine hydrochloride in water (H2O), ethanol (EtOH) and in (EtOH-H2O) mixtures with different percentages of EtOH; 30%, 50%, 70%, 100% (v/v) and at different temperatures from 293.15 to 308.15 K with a step of 5 K were measured experimentally. The conductivity of different concentrations of the phenyl hydrazine hydrochloride in aniline at the same temperatures was also measured. Depending on the measured pH and conductivity data, the solvolysis constant of phenyl hydrazine chloride was estimated. The thermodynamic parameters (free energy change, , enthalpy change, , entropy change, , and activation energy, ) of the solvolysis process were evaluated from the temperature dependence of solvolysis constant. Positive values of the standard enthalpy change ( ), indicate that the solvolysis process is endothermic process. The solvolysis constant is increase as the alcohol percentage increase from 30% - 100%, which attributed to the higher solute-solvent interaction.