Reaction coordinate diagrams are valuable tools for teaching concepts in thermodynamics and chemical kinetics. However, the examples used are typically simple 1-step reactions and not connected to experimental data. In this laboratory experiment, undergraduate physical chemistry students use electronic structure calculations to determine the geometry, vibrational frequencies, and energy of the reactants, products, intermediates, and transition states in the gas-phase ammonia synthesis reaction. Students construct the multi-step reaction coordinate diagram for the reaction, label all species, calculate the activation energy of each step, and identify which step is most likely rate limiting. There is also in-class discussion of using vibrational frequency analysis to distinguish true minima from saddle points on the potential energy surface. In this experiment, students gain valuable experience with the tools of computational chemistry and a more “hands-on” interaction with the energy landscape of a chemical reaction.

Using electronic structure calculations to construct the gas-phase ammonia synthesis reaction coordinate diagram

254th National Meeting (2017)

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