Developing and Implementing Multioutcome Experiments in Undergraduate Teaching Laboratories To Promote Student Ownership of the Experience: An Example Multioutcome Experiment for the Oxidation of Alcohols

• Kasey L. Yearty ^[1] ; Caroline E. Glessner ^[1] ; Richard W. Morrison ^[1]
  1. [1] University of Georgia

     University of Georgia

     Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 96, Nº 10, 2019, págs. 2194-2201
• Idioma: inglés
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• Resumen

  • Single-outcome experiments are used in the undergraduate instructional laboratory, particularly for large lectures associated with multiple sections of instructional laboratories, due in large part to efficiencies associated with chemical purchases, experiment preparations, and assessments. Despite the practical advantages, single-outcome experiments are not effective in encouraging students to critically analyze and interpret their acquired individual results. Instead, students are satisfied if their results are the same as or similar to all of their classmates’ results, limiting the opportunity for engagement with the laboratory content. In contrast, multioutcome experiments (MOEs) require students to explore the same chemical reaction or transformation but obtain individual results. Individualization of results is accomplished by using a set of starting materials or reagents, one of which is assigned to each student. Students do not know the identity of the assigned component but may be given possible options for its identity. Students elucidate the identity of their individualized products, using modern analytical techniques such as gas chromatography, Fourier-transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, and deduce the unknown component of their experiment. An example MOE for the oxidation of alcohols is described herein. A traditional single-outcome experiment that utilized a common household oxidizing agent (hypochlorite bleach), rather than a heavy metal-containing alternative, was modified. For the MOE modification, one unknown secondary alcohol (2-pentanol, 3-pentanol, or 3-methyl-2-butanol) was oxidized using bleach. Each student pair was assigned one of three possible unknown alcohols, all of which were constitutional isomers of secondary alcohols. Students knew the identities of the three possible alcohols. Analysis of their oxidation products was accomplished using FTIR and benchtop 1H NMR spectroscopies. Students interpreted their spectra and deduced the identity of the unknown alcohol they were assigned. This experiment provides a tangible framework to understand the applicability of the oxidation reaction and the utility of FTIR and 1H NMR spectroscopies.