Using the Colorimetric Oscillating Reaction for Simple Quantification of Ethanol in Commercial Liquors in an Undergraduate Chemistry Laboratory

Abstract

Undergraduate-level laboratory experiments that integrate multidisciplinary chemistry concepts into a single activity are very appealing and thought-provoking for chemistry students. Here, we use the oscillating chemical reaction to introduce students to the analytical detection concept. The Belousov–Zhabotinsky reaction is employed as a simple but efficient system to determine the content of ethanol in liquor samples. This experiment is based on the periodic solution color change from red to blue under the perturbation of ethanol, which can be simply followed by using a smartphone in video mode. Students can establish the calibration curve by plotting the average times required for the change in the solution color oscillating pattern from blue to red to blue, defined as the oscillation period, against ethanol concentrations. Using this strategy, students can quantify the ethanol concentrations in alcoholic samples without the need for sophisticated instruments or skilled operators. Also, this designed experiment allows all students to conduct the activity within a traditional laboratory block of time.