University students' conceptions of bonding in melting and dissolving phenomena

Abstract

Undergraduate and graduate students' predictions and submicroscopic level explanations for the melting of four materials (salt, chalk, sugar, and butter), and for the mixing of these solutes in two solvents (water and cooking oil) were collected. Twenty-three undergraduate students and seven graduate students participated in the study, and data were collected through individual semi-structured interviews. The purpose of the study was to investigate students' conceptions of how bonding is involved in both melting and dissolving processes, as well as to investigate students' ideas of specific bonds and forces involved in melting and dissolving. Three types of misconceptions about bond breaking in the process of melting were revealed, as well as three types of misconceptions about bond breaking and three types of misconceptions about bond forming in the process of dissolving. Analysis indicated that students viewed the dissolving process as occurring via a single-step mechanism or via a multi-step mechanism. Analysis also revealed that students viewed bond breaking similarly in melting and dissolving processes, likely resulting in confusion between these two processes.