On the thermodynamic feasibility of acid-base equilibria

Most undergraduate Organic chemistry textbooks contain a section on the general acid-base equilibria, strength of acids and bases, and predicting the equilibrium position of acid-base reactions (1-3). The students are taught to qualitatively predict the directions of these reactions using only the acid/base strengths or acid/base constants (pKa/pKb) without elaborating how or why they work. For example, statements like ‘stronger acids/bases tend to move towards weaker forms’ are not good explanations (1-3). Moreover, finding an answer in Analytical and Physical chemistry textbooks specific to this question is challenging (4-6). The simple thermodynamic framework put forward here can easily explain why these predictions work and allow one to quantify the direction of acid-base reactions.