Analysis of chemical equilibrium problems from exams to access university: Misconceptions and difficulties held by chemistry textbooks, students and teachers

Abstract

Four chemical equilibrium problems are analysed. This analysis concludes that problem solving relies on a particular teaching methodology which promotes rote learning recall and meaningless learning. Teachers may be transmitting some misunderstandings and even they would reinforce some persistent misconceptions. Le Chatelier’s qualitative statements were the main and almost exclusively conceptual tools used to predict equilibrium shifts. Changes in concentration caused by a variation in the volume of the equilibrium vessel were mainly associated with equilibrium shift mass changes. Gas behaviour misunderstandings were one of the most important obstacles when coping with changes in partial pressure due to changes in both mass and volume. Finally, it is reported that Le Chatelier’s principle is widely used beyond its range of applicability.