Pre-Service Teachers' Conceptions of Basic Inorganic Qualitative Analysis

Graduate teachers teaching secondary chemistry in Grades 9 and 10 in Singapore are required to prepare their students for a one-off practical examination that forms part of the General Certificate of Education Ordinary Level (O-level) chemistry examinations taken at the end of Grade 10. A qualitative analysis experiment is usually part of the practical examination. Previous research has shown that secondary students have difficulty in explaining the reactions and procedures involved in qualitative analysis (Tan, Goh, Chia, & Treagust, 2001, 2002), and a possible reason for this situation is that their teachers may also not have adequate understanding of the reactions and procedures involved, and hence, are unable to teach for understanding. A diagnostic test on O-level qualitative analysis was administered to a total 270 pre-service chemistry teachers from 1999 to 2003, and it was found that they had problems explaining the ion-exchange reactions that resulted in the formation of precipitates, the use of dilute acid in tests for anions and reactions involving complex salts such as zincates. The pre-service teachers also had difficulty explaining procedures and reactions involved when substances were heated. If the pre-service teachers have difficulty in understanding the reactions and procedures involved in qualitative analysis, it will not come as a surprise if their students also have similar difficulties with qualitative analysis.