Journal of Physical Chemistry & Biophysics
Open Access

Abstract

Determination of Thermodynamic Parameters from the Dissolution of Calcium Hydroxide in Mixed Solvent Systems by pH-Metric Method

Shamsher Ali and Azhar Ali S

In the present study the dissolution of calcium hydroxide (Ca(OH)2 in water as well as in mixed solvents systems such as (methanol + water), (ethanol + water), (1-propanol + water) and (2-propanol + water) in 0-25 percentage compositions range at 293 ± 1K and 343 ± 1K or (328 ± 1K in case of methanol) was undertaken for the determination of solubility, solubility product constant (Ksp),Gibbs free energy change (ΔGo), entropy change (ΔS°) and enthalpy change (H°) by pH-metric method. It was found that the equivalence point was decreased linearly by the increasing of the percentage composition of the mixed solvents systems. This represents that solubility and KSP values are linearly decreased. The solubility of Ca(OH)2 was decreased at higher temperature compared to room temperature. Furthermore, methanol produced minimum decreased due to its high value of dielectric constant while in 2-propanol showed maximum decreased in solubility and KSP values. On the other hand Go values were linearly increased against percentage composition of mixed solvents systems. Entropy and Enthalpy values were also changed in mixed solvent systems.