It’s a displacement reaction because sodium ions are more reactive than zinc ions

Abstract

Grade 10 (15 to 17 years old) students have difficulties in understanding ion-exchange reactions and complex salt formation involved in the tests for cations in basic inorganic chemistry qualitative analysis. Many students believed that when an insoluble hydroxide was produced from the reaction between an unknown cation and a hydroxide ion, a more reactive ion displaced a less reactive ion to form the precipitate. Students also explained that the reaction between several hydroxides and excess alkali as the precipitate dissolved when excess alkali was added because more solvent was added or that no new reagent was added and no further reaction was seen. Possible reasons proposed for such student conceptions included conceptual interference and perceptually-dominated thinking.