Student misconceptions in writing balanced equations for dissolving ionic compounds in water

Abstract

The goal of this study was to identify student misconceptions and difficulties in writing symbolic-level balanced equations for dissolving ionic compounds in water. A sample of 105 college students were asked to provide balanced equations for dissolving four ionic compounds in water. Another 37 college students participated in semi-structured interviews where they provided balanced equations for dissolving the same four ionic compounds in water and were asked to explore their thought processes at the particulate level associated with writing these equations. Misconceptions identified from these data included (i) the notion that water reacts with the ionic salts through double displacement to form a metal oxide and an acid; (ii) the notion that ionic salts dissolve as neutral atoms or molecules in water; (iii) confusion regarding the proper use of subscripts and coefficients; and (iv) the notion that polyatomic ions will dissociate into smaller particles in water. This study also describes the possible sources of these misconceptions.