Charting an Alternate Pathway to Reaction Orders and Rate Laws in Introductory Chemistry Courses

Reaction kinetics is an axiomatic topic in chemistry that is often addressed as early as the high school course and serves as the foundation for more sophisticated conversations in college-level organic, physical, and biological chemistry courses. Despite the fundamental nature of reaction kinetics, students can struggle with transforming their corpuscular reaction concepts into mathematical rate models. Here, we describe an approach to teaching rate laws at the introductory college level that draws upon model-based reasoning as the pedagogical underpinning. Collision theory, graphical analysis of kinetics plots, and transformations between concentration/time and rate/concentration representations are used to facilitate the growth in understanding about rate laws and reaction mechanisms. The learning outcome expected by the conclusion of the instructional sequence is the ability to collect and analyze kinetic data to determine reaction orders and rate laws using mathematical concepts familiar to students just beginning a course sequence in calculus. While the ideas that are discussed in this paper focus on kinetics principles as they might be presented in undergraduate general chemistry courses, we believe they would also prove useful at the advanced high school level.