Titrating Consumer Acids to Uncover Student Understanding: A Laboratory Investigation Leading to Data-Driven Instructional Interventions

Students often enter chemistry laboratory courses with a well-documented disconnect between their experiences outside the classroom and the procedures, concepts, and techniques that occur in our courses. Strong base, weak acid titration experiments are present in general chemistry laboratories but also relate to foods our students are familiar with. An experiment using commonly consumed acids offers an opportunity to decrease the distance students may feel between the laboratory and everyday chemistry. By investigating reagents that may be purchased from the grocery store (citric acid in citrus soda, acetic acid in vinegar, or acetyl salicylic acid in aspirin), students gain an opportunity to see the chemistry they are learning in their everyday foods and medicines. This experiment uses an automatic titrator such as LabQuest to obtain the titration curve of each food acid. Students then use the shapes of these curves to identify a given unknown solid and aqueous version of one of these acids. This was carried out in a university general chemistry lab course, and quantitative and qualitative analysis of how the class approached the graphical identification process was performed. This article lays out an approach to teaching acid–base titrations that holds the potential to link students’ chemistry lives both in and outside of the classroom while offering instructors a low-stakes method of evaluating student understanding. The development of this food acid investigation and modifications possible for online or hybrid learning are discussed.