Discovering the Thermodynamics of Simultaneous Equilibria An Entropy Analysis Activity Involving Consecutive Equilibria

An activity is presented in which the thermodynamics of simultaneous, consecutive equilibria are explored. The activity is appropriate for second-year high school or AP chemistry. Students discover that a reactant-favored (entropy-diminishing or endergonic) reaction can be caused to happen if it is coupled with a product-favored reaction of sufficient entropy production or exergonicity. A variety of six product-favoring reactions are individually coupled with the reactant-favored reaction. The experimental results are correlated with the change in the entropies of the universe (?Suniv), the change in the standard-state free energies (?rG°), and the various equilibrium constants (K).