Applying the concept of conjugation to the Br⊘nsted theory of acid‐base reactions by senior high school students from Germany

Abstract

The purpose of this descriptive study was to identify misconceptions held by German senior high school students about the Br⊘nsted acid‐‐base theory. Test items were developed that can be used to uncover student problems in this area. A sample of 4291 senior high school students in grades 11‐13 completed paper‐and‐pencil tests on acid‐‐base theory. Discussions in individual classes were videotaped while the students solved test questions. The results indicate that German senior high school students have two misconceptions about conjugate acid‐‐base pairs. First, they confuse non‐conjugate and conjugate acid‐‐base pairs. One possible explanation for this is that the distinction between the two associations is seldom mentioned in US and German chemistry textbooks. Second, students regard pairs of positively and negatively charged ions as conjugate acid‐‐base pairs as if they somehow neutralized each other. Students use chemical terminology, but misconceptions occur because the terminology is misleading. For example, the original meaning of certain terms like neutralization has changed whereas labels characterizing the reaction have remained. This shift of meaning is also not mentioned in textbooks. The result suggests that these problems ought to be addressed in chemistry textbooks and in the classroom teaching of chemistry. If teachers are more aware of students’ misconceptions they will be better able to remove them.