The Adverse Effects of Le Chatelier's Principle on Teacher Understanding of Chemical Equilibrium

摘要

Chemistry education researchers have noted the inadequacy of Le Chatelier’s principle (LCP) for decades (1–12). They have shown how apparently reasonable applications of LCP can result in incorrect predictions about the effects of changes in concentration, volume, pressure, or temperature on chemical systems at equilibrium. Because LCP has no value for chemistry teachers and students other than historical interest, some researchers (13–19) have criticized the over-emphasis of LCP in the school chemistry curriculum. They have recommended the use of the equilibrium law, reaction quotient, and van’t Hoff equation to predict the direction in which a chemical equilibrium system will shift when it is disturbed. Yet little progress has been made to delete LCP from the school chemistry curriculum. Textbooks of high school chemistry or college chemistry published in many countries such as the United States, the United Kingdom, Australia, Canada, and China still rely on LCP as the major predictive tool. Le Chatelier himself described three different statements of LCP (18). Petrucci, Harwood, and Herring (20) emphasized that it is hard to state LCP unambiguously, but they believed that the essential meaning of LCP is as follows