Teo, Tang Wee

There is increasing interest in the research of alternative conceptions in electrochemistry as it is ranked as one of the most difficult topics in chemistry (Garnett & Treagust, 1992a, b). This study is the first to be carried out within the Singapore context which specifically diagnoses students' understanding in electrochemistry. It aims to identify Singapore junior college students' alternative conceptions of redox processes in electrochemistry. Its primary purpose is to bring the curriculum planners', teachers' and students attention to the existence of alternative conceptions on electrochemistry, so as to improve the teaching and learning of this topic.

This study replicated and extended the research done by Garnett et. al. (1995), Sanger and Greenbowe (1997a, b), Ogude and Bradley (1994) and other researchers. A list of conceptual and propositional knowledge statements adapted from previous studies by Garnett and Treagust (1992a, b) helped to identify the knowledge base necessary for students to understand electrochemistry. Alternative conceptions that had been reported in several other studies were also consolidated to give a more comprehensive list of alternative conceptions related to electrochemistry.

The list of conceptual and propositional knowledge statements and alternative conceptions provided the framework for the development of an open-ended questionnaire which was administered to about sixty second year junior college students (17 to 18 years old). This was followed by semi-structured interviews with four selected students to further probe their understanding of electrochemistry.

The alternative conceptions identified in the study were very similar to those identified in previous related studies. The areas of alternative conceptions surfaced from this study include the charge law, electric current, standard half-cell, current in an electrochemical cell and charges on the electrodes of electrochemical cells.

Interestingly, one new alternative conception was surfaced from this study :

The electrodes of the electrochemical cell must be placed in two solutions of different concentrations.

The study also revealed that the textbooks used in junior colleges may be inadequate teaching and learning materials. The two highly recommended A-level textbooks by Briggs and Ramsden were scrutinised and found to have excluded content knowledge that would aid in the understanding of electrochemistry. In addition, they were found to contain information that could mislead students and cause them to develop alternative conceptions. Some of these information include stating that the charges assigned to half-cells were identified from their positions in the diagram and assigning oxidation numbers by changing covalent bonds into 'electrovalent bonds'.