Assessment of students' mental models regarding hydrogen chloride molecule and its ionization properties among secondary school students

Abstract

Learning chemistry subject requires students to master fundamental knowledge such as type of particles and how they change from one type to another i.e. from molecules to ions. This study investigates students' understanding of acid's ionization in term of its microscopic representation. The study makes use of qualitative method that apply content analysis procedures to reveal students thinking about dissolution process. The dissolution of hydrogen chloride gas in water and tetrachloromethane were presented upon students using diagram. 38 students were purposely selected to answer a semi-structured interview regarding the chemical process. Students were asked to make their own drawings in order to reveal their understandings. The drawings were analyzed via content analysis, which were then corroborated by conducting semi-structured interview. While many students were able to draw appropriate depiction such as gas moleculesas diatomic but the result of the study indicates that only 6 students from 38 participants were able to show appropriate depiction of the ionization process of hydrogen chloride in water. This study reveals students' mental models that involves certain patterns of arrangement for hydrogen chloride either in gas state, aqueous state or in organic solvent i.e. discrete atomic arrangement, diatomic molecule, clumping, random arrangement and wrong compound (wc). Most importantly, this study indicates students were still holding on to their lower secondary science syllabus knowledge that is not suitable to be applied in chemistry upper secondary school level. Thus teachers are suggested to ensure students are able to alter their prior knowledge to suit new learning in chemistry.