A Caffeinated Boost on UV Spectrophotometry: A Lab for High School Chemistry or an Introductory University Chemistry Course

• Autores: Kevin Dooling, Kurt Bodenstedt, Michael F. Z. Page
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 90, Nº 7, 2013, págs. 914-917
• Idioma: inglés
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• Resumen

  • This laboratory experiment challenges students to identify the country of origin of raw coffee beans from around the world by calculating the percent caffeine and percent water in the supplied samples. The implementation of this experiment enables students in introductory chemistry classes to gain greater understanding of the chemical analysis process and the Beer–Lambert law. Using commercially available raw (green) coffee samples, students extract caffeine from the grounds as an aqueous solution and determine the percent caffeine using UV–vis spectrophotometry. In a second portion of the experiment, raw beans are roasted to determine the percent water content. Using both pieces of data, students are asked to identify the country of origin of given coffee samples in which the percent caffeine ranged from 1.14 to 1.80% (w/w) and the percent water loss ranged from 3.27 to 10.8% (w/w).