Measurement of the Standard Free Energy Change of Chemical Reactions by the Chemical Equilibration Technique Using a Thermogravimetric Apparatus: A Novel Approach

Abstract

The current work aims at determining the standard free energy change (⧍G°) as a function of temperature (T), using the chemical equilibration technique. A novel approach was made to find the equilibrium state with the assistance of a Thermogravimetric Analyzer. The ⧍G° for lead carbonate dissociation reaction PbCO 3 (s) = PbO(s) + CO 2 (g) was calculated as an example. The weight of PbCO 3 started decreasing at specific temperature termed as equilibrium temperature. At this temperature ⧍G = 0 and the equilibrium relation between ⧍G° and the equilibrium constant K applied. Below this temperature, when there was no change in weight, ⧍G > 0, and above this temperature, when the weight kept changing for continued dissociation of PbCO 3 (s), ⧍G < 0. The obtained ⧍G° for PbCO 3 (s) matched closely with the information found within in the literature.