Beer’s Law and a Bubble Wall: Designing an Innovative Undergraduate Lab with Analytical Chemistry’s Most Common Equation

While bubbles may have captured our attention as children, there are still rich pedagogical benefits that can be gleaned by examining the beloved bubble wands that made these colorful, floating balloons. Specifically, students can answer the question “how thick is a bubble wall?” by conducting a new type of analysis using the Beer–Lambert law. Here, students still create a calibration curve to extract the molar absorptivity coefficient of a known analyte; however, they then make an absorbance measurement through the soap film of a bubble wand─not a cuvette─of known analyte concentration and solve for the path length (i.e., the bubble wall’s thickness). This novel way of presenting Beer’s law and UV–vis absorption spectroscopy demonstrated positive pedagogical impact, as indicated by responses to a postlab questionnaire. Further, as surfactant-based systems have interesting applications in sensing, chemical engineering, and diverse industries, this experimental design involving bubbles helps students develop important critical thinking skills and introduces them to wide-ranging analytical and industrial applications.