Alternative conceptions of common salt hydrolysis among upper-secondaryschool students

Abstract

Reactions in aqueous solutions are an important part of chemistry education. As experience shows, they are particularly difficult for students to understand. Hydrolysis is one such reaction. It occurs in organic and inorganic compounds with either covalent and ionic structures, but salt hydrolysis is a special example. Salt hydrolysis is complex, and to understand it, students must consider the reaction equilibrium, dissociation process, and acid-base properties of reactants and products. Additionally, in the uppersecondary- school curriculum, hydrolysis is described only qualitatively, which can lead students to misinterpret hydrolysis and solution equilibrium. In this study, 235 upper-secondary-school students answered questions about the acidity of common salt solutions and tried to justify their responses by writing appropriate chemical equations. An analysis of the answers revealed the students’ alternative conceptions and misconceptions. The character of the misconceptions showed that they are school-based and largely caused by excessive simplification of the process as well as the usage of inappropriate analogies.