When introducing Beer's Law, many laboratory experiments involve colored food dyes and performing serial dilutions of a stock solution.  If more authentic approaches are used, then a deeper understanding of Beer's law can be experienced in introductory and advanced separations courses.  At California State Polytechnic University, Pomona, we developed a two-part Beer's Law experiment based on extracting caffeine from raw coffee beans from around the world.  Using a calibration curve of pure caffeine, students can determine the percent caffeine in a set of coffee beans.  The second portion of the experiment includes roasting beans from the same country to determine the percent water loss.  Using all data collected, students can successfully determine the origin of their samples by applying mathematical concepts along with Beer's Law in a real-world scenario.  Based on data collected, we found that percent caffeine ranged from 1.2-1.8% (w/w), and percent water loss ranged from 6.2-10.9% (w/w).

Beer's law:  A caffeinated take on the classic experiment

243rd National Meeting (2012)

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