Abstract
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.
Highlights
Calcium hydroxide is used in a broad range of industrial, professional and consumer applications
The solubility of solutes in mixed solvents is of great practical importance since many industrial process as well as laboratory procedures call for the use of solvent mixtures
In mixed solvent systems the pH of Ca(OH)2 was gradually decreased by the addition of each volume of Standard HCl (0.03 ± 0.001 M) by the mutual exchange of H+ and OH ions from acid with analyte after the equivalence point, pH of mixture is decreased sharply in increasing the H+ ion in solution
Summary
Calcium hydroxide is used in a broad range of industrial, professional and consumer applications. In the present research work, pH metric method was used for the study of the influence of mixed solvent system on the solubility Ksp, Gibbs free energy, entropy and enthalpy of Ca(OH)2. In mixed solvent systems the pH of Ca(OH)2 was gradually decreased by the addition of each volume (ml) of Standard HCl (0.03 ± 0.001 M) by the mutual exchange of H+ and OH ions from acid with analyte after the equivalence point, pH of mixture is decreased sharply in increasing the H+ ion in solution.
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