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  Home > JCE Print > Journal of Chemical Education > Issues > 2007  > September  >
In the Laboratory
Coupling Molecular Modeling to the Traditional "IR-ID" Exercise in the Introductory Organic Chemistry Laboratory
Heather Stokes-Huby and Dale E. Vitale
Department of Chemistry and Physics, Kean University, Union, NJ 07083
Cover
September 2007
Vol. 84 No. 9
p. 1486

Abstract
This exercise integrates the infrared unknown identification ("IR-ID") experiment common to most organic laboratory syllabi with computer molecular modeling. In this modification students are still required to identify unknown compounds from their IR spectra, but must additionally match some of the absorptions with computed frequencies they generate from computer molecular models. They then use animation of the corresponding bonds in the model to obtain descriptions of the observed vibrations. This affords a vivid conception of the dynamic nature of covalent bonding that is not available from the traditional experiments. The computational exercises also provide students with a method for assigning IR absorptions to specific molecular vibrations when no reference is available. The animations also demonstrate the fundamental fact that all the bonds in a given molecule vibrate even if some of them do not absorb IR radiation. Suggestions are made for the types of compounds to be used and the computational software needed. Advice is also given on how to configure the experiments, computations, and networking so that time is not an issue. Emphasis is on the IR experiment, and a high level of computational chemistry expertise is not required.
Supplement
Student handouts for the IR-ID experiment and introductory molecular modeling with Spartan are available. Also included are notes to instructors on networking the IR spectrometers.
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Citation
Stokes-Huby, Heather; Vitale, Dale E. J. Chem. Educ. 2007, 84, 1486.
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Keywords
Computational Chemistry; Computer-Based Learning; Hands-On Learning / Manipulatives; IR Spectroscopy; Laboratory Instruction; Liquids; Organic Chemistry; Second-Year Undergraduate
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History
Created:
Last Updated:
7/23/2007
8/16/2007
 Caution! 
Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations.
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