A Gibbs Free Energy Change (\(\Delta\)G) and Aqueous Dissociation of Benzoic Acid at Kelvin Range

Abstract

In chapter, we have described a thermodynamic based Gibbs free energy change (\(\Delta\)G) during in aqueous dissociation of benzoic acid (C₆H₅COOH) in between of 288 upto 318 Kelvin temperature range. The dissociation constant (Ka) of benzoic acid for aqueous solutions have been determined by applying of titration method against standard basic solution of NaOH at different concentrations as 0.05, 0.10, 0.30, 0.40 and 0.50 of NaCl. In observation, the value of Ka is being inversely proportional with increase the temperature (289 K - 303 K), and above at higher temperature in between 303 K to 314 K, it being directly proportional. This is report that, there are no regular correlation in this temperature range and Ka of that acid. The graph's plot displays the benzoic acid's Ka value, which is 4.176 at 298 K. Thus, in finding of precious results for benzoic acid dissociation in aqueous an applying the Gibbs free energy change relationship (\(\Delta\)G = \(\Delta\)H - T\(\Delta\)S) for endothermic or exothermic reaction process at standard condition of thermodynamic parameters. These parameters value (in kJ.mol^-1) are being as \(\delta\)G = 12.507, \(\Delta\)H = 3.823 and \(\Delta\)S = -29.14. It demonstrates that acid dissociation into an aqueous solvent is an endothermic, non-spontaneous process with entropy (\(\Delta\)S) at 298 K.