A LABEL AS A HIDDEN PERSUADER - CHEMISTS NEUTRALIZATION CONCEPT

The original meaning of neutralization has shifted in the course of its 300‐year development. As chemistry teaching deals with both the old and new definitions, one can assume that students are liable to have difficulties in applying the concept correctly. The aim of this study has been to identify and describe the problems students have with the concept of neutralization. About 7500 students were randomly assigned test items referring to the concept of neutralization. Analysis of the answers showed that many students understand the concept in its original meaning. They assumed that in any neutralization reaction a neutral solution is formed, even if a weak acid or base takes part in the reaction. Other students came to the same conclusion assuming that neutralization is an irreversible reaction. Not until the students realize that two reactions have to be taken into account, can they understand what happens when, for example, a weak acid reacts with a strong base. These are the two equilibrium reactions: (a) the protolysis of the weak acid, and (b) the reaction between hydrogen ions and hydroxide ions forming water. © 1991 Taylor & Francis Group, LLC.