From Chemical Forces to Chemical Rates: A Historical/Philosophical Foundation for the Teaching of Chemical Equilibrium

Abstract

With this paper, our main aim is to contribute to the realisation of the chemical reactivity concept, tracing the historical evolution of the concept of chemical affinity that eventually supported the concept of chemical equilibrium. We will concentrate on searching for the theoretical grounds of three key chemical equilibrium ideas: 'incomplete reaction', 'reversibility' and 'dynamics'. In addition, the paper aims to promote teachers' philosophical/ historical chemical knowledge. The starting point of this historical reconstruction will be the state of the art in the construction of the first affinity tables, based on the concept of elective affinities, during the 18th century. Berthollet reworked this idea, considering that the amount of the substances involved in a reaction was a key factor accounting for the chemical forces. Guldberg and Waage attempted to measure those forces, formulating the first affinity mathematical equations. Afterwards, the first ideas providing a molecular interpretation of the macroscopic properties of equilibrium reactions are presented. Eventually, theoretical chemists integrated previous findings into a new field: thermodynamics. This historical approach may serve as a base for an appropriate sequencing of the teaching and learning of chemical equilibrium. Hence, this paper tries to go beyond the simple development of teachers' conceptions of the nature of chemistry, for it gives suggestions about how teachers may translate such understandings into classroom practice.

Assessment: A Suggested Strategy for Learning Chemical Equilibrium

“…This could be considered as a strategy for changing the idea about assessment as a result, because the main goal of the instrument was to ask the conditions for solving the problem. In this matter, it is relevant to mention that students prefer examinations which emphasize understanding and analysis, rather than tests of plain knowledge [81]. Nonetheless, despite awareness of the students' exam-type preferences, science teachers continue to administer their own conventional examinations.…”

Kimya Öğretmen Adaylarının Kimyasal Dengeye İlişkin Zihinsel Modelleri

“…Son olarak, öğretmen adaylarıyla yapılan çalışmalara bakıldığında öğretmen adaylarının atom kavramı (Kiray, 2016); kimyasal reaksiyonlar (Yüce, 2013); kimyasal bağlar (Ulutaş, 2010) (Ganaras, Dumon ve Larcher, 2008;Harrison ve De Jong, 2005;Maia ve Justi, 2009;Quilez, 2009). Fakat yapılan çalışmalar incelendiğinde kimyasal denge öğrenilmesi ve öğretilmesi zor bir konu olarak kabul edilmektedir (Doymuş, 2008;Quilez, 2004;Quílez-Pardo ve Solaz-Portolés, 1995).…”

Research-oriented chemistry teacher: Teaching and learning of chemistry concepts and phenomena (part IV): Historical approach on chemistry education

“…(Justi & Gilbert, 1999) Luonnontieteiden luonnetta tuotiin opetuksessa esille Le Châtelier'n periaatteen kehittymisen avulla. Le Châtelier'n periaatetta ei kehitetty hetkessä, vaan se oli pitkällisen vuosikymmeniä jatkuneen tieteellisen tutkimuksen tulos (Quilez, 2006…”