There are inherent difficulties in a subject like chemistry particularly the notion of a chemical reaction. In this paper the difficulties are discussed from a teaching and learning perspective and from a history of chemistry perspective. Three teaching/learning studies of the incompleteness of the iron(III) thiocyanate reaction in chemical equilibrium are reviewed and it is shown that a recent historical study of the iron(III) thiocyanate reaction has the potential to challenge the interpretation of the incompleteness of the reaction. This establishes a controversial context where students can be introduced to epistemic thinking, that is, how to interrogate chemistry data and form a conclusion which resonates with what we know about the nature of science. A curriculum suggestion for pre-service chemistry teachers is provided.

在诸如化学的学科中存在固有的困难，特别是化学反应的概念。本文从教学和学习的角度以及化学史的角度讨论了这些困难。综述了三项有关化学平衡状态下硫氰酸铁（III）反应不完全的教学研究，结果表明，最近关于硫氰酸铁（III）反应的历史研究有可能挑战对不完全反应的解释。反应。这就建立了一个有争议的环境，在这里可以向学生介绍认知思维，即如何审问化学数据并得出结论，与我们对科学本质的了解相呼应。提供了针对职前化学老师的课程建议。