A Review of the Essence of Stability Constants in the Thermodynamic Assessments of Chemical Compounds

Abstract

Background: This treatise discusses the following topics: • Chemical compounds • Factors affecting stability of chemical compounds • Stability constants • The significance of stability constants vis-a-vis equilibrium constant, Keq The different forms of stability constant are reviewed and the thermodynamic assessment of stability constant is explained. Method: The approach involved the review from reputable authors and writers, of the topics that are associated with stability constant and the generalization is remarked following the thermodynamic assessment of the stability constant of chemical compounds. Findings: The thermodynamic analysis of stability constant of chemical compounds and of reactions shows that reactions proceed in the direction of decreasing Gibb’s free energy, G, where the standard reaction Gibb’s free energy, ∆rG0 = ∆fG0 (B) - ∆fG0 (A), defines the formation of the pure substance B, from the pure substance A, at its standard state. Conclusion: RTlnK = -∆r G0 is the link between thermodynamic data and the equilibrium constant (stability constant), K. When ∆r G0 > 0, K < 1 and at equilibrium the partial pressure of A exceeds that of B. This means that the reactant A is favored in the equilibrium. When ∆r G0 < 0, K > 1 and at the equilibrium the partial pressure of B exceeds that of A. The product B is favored in the equilibrium. The equation is an exact thermodynamic relation. The equilibrium constant, K, when expressed in terms of activities, is called a thermodynamic equilibrium constant