Disentangling the Dissolution of Ionic and Molecular Compounds: Alternative Conceptions and Teaching Considerations in Chemistry

Students often develop alternative conceptions about fundamental chemistry concepts, particularly regarding the dissolution of ionic, molecular, and acidic compounds. These naïve conceptions, which persist despite formal instruction, may stem from the ways in which chemistry is taught at the high school level. This study investigates how high school chemistry teachers conceptualize and teach dissolution as well as how alternative conceptions relating to these concepts arise in student understanding. Semistructured interviews were conducted with high school chemistry teachers and second-semester general chemistry students to analyze their understanding of dissolution through the lens of Johnstone’s triangle, which emphasizes the interplay between macroscopic observations, submicroscopic interactions, and symbolic representations. Findings indicate that teachers frequently rely on macroscopic demonstrations and submicroscopic particle models while de-emphasizing symbolic representations, particularly balanced chemical equations. Many teachers exhibited fragmented conceptions, often portraying HCl as an ionic compound or omitting key molecular-level processes in describing its dissolution. Furthermore, inconsistencies in textbook explanations and instructional language─such as the interchangeable use of “dissociation” and “ionization”─contribute to the confusion. As a result, students struggle to connect chemical equations with molecular-level processes, reinforcing alternative conceptions that persist in college-level chemistry. This study underscores the importance of helping students integrate symbolic representations alongside macroscopic and submicroscopic models. By explicitly addressing these instructional gaps and refining pedagogical approaches, educators can help students develop a more accurate and meaningful understanding of dissolution, ultimately supporting their progression in chemistry learning.