Le Châtelier’s Principle a Language, Methodological and Ontological Obstacle: An Analysis of General Chemistry Textbooks

Abstract

This study discusses how textbook educational approaches concerning Le Châtelier’s principle (LCP) may hinder student comprehension and prediction of chemical equilibrium disturbances. Firstly, after summarising students’ LCP erroneous assertions/explanations, a categorisation of the potential barriers that may originate student misunderstandings is performed. The discussed obstacles are the following: (a) language difficulties; (b) limited range of applicability; (c) official examinations and chemistry syllabi and (d) educational research. Then, it is examined how general chemistry textbooks’ authors deal with the evolution of chemical equilibria when they are disturbed. The different qualitative formulations of LCP provided in textbooks use mainly polysemic teleological vocabulary, which are difficult to understand in this context. Moreover, textbooks’ writers normally do not specify the conditions under which an equilibrium system is disturbed. In this textbook presentation, LCP is introduced as an easy and infallible rule, without limitations. Thus, several problematic perturbations reported in the chemical education research literature are not considered in these materials. Hence, this study concludes that their lacks and misleading use and application of LCP may certainly affect proper student understanding of the concepts related to chemical equilibrium disturbances.