Inquiry-Based Laboratories for Students to Investigate the Concepts of Acid-Base Titration, p K<inf>a</inf>, Equivalence Points, and Molar Absorption Coefficients

Abstract

This research developed learning activities for students to explore and connect the concepts of acid-base titration, equivalence points, pKa, and molar absorption coefficients. Polyphenolic compounds consisting of p-coumaric acid (CMA), caffeic acid (CFA), and 3,4,5-trihydroxycinnamic acid (3,4,5-THCA) were selected as study models. The inquiry-based learning activities consisted of four phases, including in-classroom, prelaboratory discussion, in-laboratory work, and postlaboratory discussion. This research was conducted through a single group pretest-posttest design, and the learning activities were implemented with biochemistry undergraduate students. Data were collected using conceptual pretest and posttest, questionnaires, and laboratory reports. The paired-sample t test results showed that the mean posttest score (51.29 ± 10.46) was significantly higher than the mean pretest score (19.00 ± 5.90). The results implied that students had a better understanding of the concepts and the links between the concepts of acid-base titration, pKa, equivalence points, and molar absorption coefficients. These findings were supported by information from questionnaires and laboratory reports. The results showed that the students had moderately positive attitudes toward laboratory activities, the instructor, and the content. Overall, the results indicated that the laboratory activities embedded with the inquiry-based approach were effective, as they enhanced the students' understanding of concepts and promoted students' positive attitudes toward laboratory activities.