Gibbs Free Energy Change (∆G) in Aqueous Dissociation of Benzoic Acid at Temperature ‘K’: A Thermodynamic Study

Abstract

In article, we have reported a thermodynamic based study of the Gibbs free energy change (∆G) in aqueous dissociation of benzoic acid at Kelvin temperature range in between of 288 K to 318 K. Thermodynamically, at this Kelvin temperatures range the dissociation constant (Ka) of benzoic acid into aqueous solutions have been determined by applying of titration method against standard basic solution of NaOH at different concentrations or ionic strength of NaCl. In observation, the value of Ka is being inversely proportional with respect to temperature in between 289 K to 303 K, and at higher temperature in between 303 K to 314 K, it being directly proportional. This is reported that, there are no regular correlation in between temperature and Ka of that acid. In graph, the plot has shown the value of Ka of benzoic acid is being 4.176 at 298 K temperature. Thus, in finding of precious results for benzoic acid dissociation into water an applying the Gibbs free energy change relationship (∆G = ∆H - T∆S) for endothermic or exothermic reaction process at standard condition of thermodynamic parameters. These parameters value (in kJ.mol-1) are being as ∆G = 12.507, ∆H = 3.823 and ∆S = -29.14. And, at 298 K, it is show that the acid dissociation into aqueous solvent is an endothermic and non-spontaneous process with ordered entropy (∆S).