Vitamin C as a Model for a Novel and Approachable Experimental Framework for Investigating Spectrophotometry

This laboratory experiment, designed for undergraduate nonmajors or advanced high school students, attempts to demystify the technique of spectrophotometry by utilizing a hands-on, real-world approach. Modification of the reaction for the formation of Fe[(bpy)(3)](2+) allows students to interact with vitamin C, a compound with which they are familiar from daily life, and observe its concentration in an approachable experimental framework. These connections are emphasized in a protocol designed to help students correlate visual and quantitative data by generating their own standard curve against which they compare unknown solutions. This experiment was found to decisively increase students' understanding of concepts related to standard curves and spectrophotometry, and it also demonstrated gains in student understanding of solubility and its impact on colorimetry. Opportunities within this experimental framework exist for additional conceptual development related to the chemical, technological, and social aspects of the assay. Combined with its pedagogical effectiveness, this represents an excellent resource for diverse chemistry classrooms.