Chemical Reaction Stoichiometry: A Key Link between Thermodynamics and Kinetics, and an Excel Implementation

The Law of Conservation of Mass (LCM) is one of the most important principles in chemistry. It applies to both closed and steady-state open flow systems undergoing chemical change. Various special methods are generally taught for its implementation, including inspection, oxidation-reduction, and ion-electron approaches, which typically fall under the topic of "balancing a chemical equation". However, apart from the simplest case described by a single such equation, only matrix methods are applicable.

This paper describes Chemical Reaction Stoichiometry (CRS), and its implementation of the LCM for chemically reacting systems by its expression in terms of a nonunique set of independent chemical equations of the appropriate number. Such equations have the superficial appearance of, but are distinct from, an actual chemical reaction mechanism. The underlying matrix method is based on ideas from basic linear algebra; in addition to being generally applicable to systems of any complexity, it obviates the need for the aforementioned special methods in single-reaction systems.

We provide an easy-to-use spreadsheet implementation of CRS that includes many worked examples.