Title: Exploring Students’ Understanding of the Relationship Between Acid-Base Conjugate Pairs and Their Relative Strength
Authors: Melissa W. Anderson, Nadia Carmosini, Katherine Friesen, and Yevgeniya Turov; Department of Chemistry, University of Wisconsin – La Crosse
Discipline/Field: Chemistry and Biochemistry
Submission Date: June 2013
Abstract: During our time working with students in CHM 104 [General Chemistry II], we have observed that concepts related to acid-base equilibrium are particularly challenging for students. Even after a significant amount of lecture and laboratory instruction, students still appear to have only a superficial understanding of the topic at the completion of the course. Therefore, the main goal of this study was to improve students’ understanding of the relationships between acids and bases and their conjugates, one of the most fundamental aspects of acid-base chemistry. This goal was approached by modifying the first lab experiment to deal with acid-base chemistry (Experiment #5). Students typically arrive to a lab period having skimmed the experiment procedure at best. Therefore, the instructor spends a significant amount of instruction time (~45 min) discussing the theory behind the experiment, as well as practical aspects of the lab. By removing the bulk of the pre-lab instruction out of the set experiment time (3 hours), and also asking students to complete work before they attended the lab, we hoped to focus their attention to the outcomes of the experiment having come to lab more prepared than in the past. Through this lesson study we found the modifications made to the experiment were useful in allowing the students to demonstrate their proficiency with equation writing skills, and also reinforced their understanding of many of the differences between acids and bases. However, common misunderstandings surrounding pKa, pKb, and pH we not fully addressed and still need some attention.