THERMODYNAMIC BASED AQUEOUS SOLVATION AND DISSOCIATION OF BENZOIC ACID

In article, we have reported a thermodynamic based study of aqueous solvation of benzoic acid (C₆H₅COOH) at 288 to 318 Kelvin temperature. At this temperature range the dissociation constant (Ka) of benzoic acid into aqueous solvent has been determined by applying of titration method against standard basic solution of NaOH at different ionic strength of NaCl. Although, in observation, the value of Ka is being inversely proportional in respect of temperature in between 289 K to 303 K, and at higher temperature in between 303 K to 314 K, it being directly proportional. This reports that, there are no regular correlation in between temperature and Ka of that acid. Graphically, the plot has shown the value of Ka of benzoic acid is being 4.176 at 298 K temperature. In finding of precious results for benzoic acid solvation and its dissociation into water the applying Vant Hoff equation with Gibbs free energy change relationship (∆G = ∆H - T∆S) for reaction (endothermic or exothermic) process at standard condition of thermodynamic parameters as in terms of enthalpy (H) and entropy (S). Where, the thermodynamic parameters value (in kJ.mol^-1) are being as ∆G = 12.507, ∆H = 3.823 and ∆S = -29.14, but, at 298 K it is show that, the acid dissociation into aqueous is an endothermic process and non-spontaneous.