Analyzing General Chemistry Texts’ Treatment of Rates of Change Concepts in Reaction Kinetics Reveals Missing Conceptual Links

Abstract

Change over time is a crosscutting theme in the sciences that is pivotal to reaction kinetics, an anchoring concept in undergraduate chemistry, and students’ struggles with rates of change are well-documented. Informed by the education scholarship in chemistry, physics, and mathematics, a research team with members from complementary disciplinary backgrounds developed a rubric to examine how 10 general chemistry textbooks used by top producers of American-Chemical-Society-approved chemistry baccalaureates treat rates of change concepts in reaction kinetics. The rubric is focused on four categories of students’ challenges that emerged from the literature review: (i) fluency with graphical representations, (ii) meaning of sign of rate of change, (iii) distinction between average and instantaneous rates of change, and (iv) connections between differential and integrated forms of the rate laws. The analysis reveals interesting patterns but also variability among the texts that, intriguingly, is not explained by the degree to which a text is calculus-based. An especially powerful aspect of the discipline-based education research lens is its ability to reveal missing conceptual links in the texts. For example, the analysis makes apparent specific gaps in the supports needed to help students move between representational forms (words, symbols, graphs) in the development of the differential form of the rate laws. The paper discusses the implications of the findings for chemistry instructors and chemical education research.

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