Abstract :
[en] The primary objective of this thesis is to improve the teaching of entropy and the second law of thermodynamics in introductory thermodynamics courses at the tertiary level. In the introduction, we discuss the known pedagogical challenges associated with physical chemistry, thermodynamics, and entropy, while also presenting the theoretical framework of this thesis—conceptual change. Part I explores the relationship between knowledge, educators, and students across three chapters. The first chapter examines the use of metaphors and figures in textbooks, revealing that the "disorder" metaphor commonly structures explanations of entropy. Furthermore, textbook figures frequently depict molecular movement in an incomplete manner, potentially contributing to the misconception of entropy solely as spatial disorder. In the second chapter, two cohorts of thermodynamics students (scientists and engineers) were given a pre- and post-course questionnaire to explore their conceptions of entropy in a macroscopic-oriented course. The findings support the prevalence of several alternative conceptions identified in the literature and introduce new ones, some of which appear to stem from the use of the disorder metaphor. The third chapter presents a survey of thermodynamics instructors in French-speaking Belgium, aiming to understand their perspectives on the challenges of teaching entropy. The results show that the difficulties experienced by educators mirror those identified in the literature, such as the abstract nature of the concepts. Most respondents acknowledged using the disorder metaphor for various reasons, many stating that they do not disclose its limitations to their students.
In Part II, we propose new methods for teaching entropy and entropy-related concepts. A systematic review of solutions suggested in the literature identifies numerous, though often untested, hands-on and theoretical approaches to improving entropy instruction. Building on the findings of Part I and the literature review, we tested a microscopic-oriented teaching method with undergraduate students in a quasi-experimental control-intervention setting, showing a modest improvement of students' conceptions of entropy. This study also demonstrated the compatibility of integrating elements of statistical thermodynamics (such as the Boltzmann distribution, microstates, and macrostates) into introductory courses that are macroscopic-oriented. We extended this teaching approach to two other fundamental thermodynamic concepts—colligative properties and Gibbs free energy, by highlighting their conceptual connection to entropy and molecular degrees of freedom. The study on Gibbs free energy also addressed the relationship between entropy and chemical equilibrium, using an interactive lecture format to gather feedback on how students perceived this innovative teaching approach. Finally, entropy alternative conceptions were further investigated through a true-false, congruent-incongruent task administered to undergraduate students. This task provided additional evidence of the prevalence of some alternative conceptions about entropy and tracked their evolution before and after the macroscopic-oriented course.
