Relating students' reasoning to the history of science: The case of chemical equilibrium

In this study, the reasoning of students, who are introduced to the concept of chemical equilibrium, was related to the historical development of this concept. In the first stage of the study, remarkable similarities were observed between students' reasoning on the issue of incomplete chemical conversions and the reasoning of 19th-century scientists, especially when molecular notions were included. In the next stage of the study, some authentic problems and questions, that were essential in the historical development of chemical equilibrium, were presented to students. It appeared that they recognised the significance of these problems and questions. Moreover, most students were eager to find explanations. Students, reasoning in molecular terms, would sometimes explain these problems in terms similar to historical explanations. Other students, however, suggested explanations in non-molecular terms, which, although chemically valid, did not appear to have historical antecedents. It was concluded that the study of authentic historical sources may inspire the design of effective teaching activities.