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2007
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In the Laboratory
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Gas Clathrate Hydrates Experiment for High School Projects and Undergraduate Laboratories
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Melissa P. Prado, Annie Pham, Robert E. Ferazzi, Kimberly Edwards, and Kenneth C. Janda
Department of Chemistry, University of California, Irvine, Irvine, CA 92697
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November 2007
Vol. 84 No. 11
p. 1790
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| Abstract |
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We present a laboratory procedure, suitable for high school and undergraduate students, for preparing and studying propane clathrate hydrate. Because of their gas storage potential and large natural deposits, gas clathrate hydrates may have economic importance both as an energy source and a transportation medium. Similar to pure ice, the gas hydrate structure consists of a lattice of water molecules held together by hydrogen bonds. However, the gas hydrate lattice is more complex than that of ice: "host" cages are formed in which the "guest" molecules are trapped. Despite the fact that the gas hydrate lattice is less stable than the ice lattice, the van der Waals forces between the guest molecules and the host lattice stabilizes the overall structure. Propane clathrate hydrate is an especially interesting example because the solid is a mixture of two chemicals that are immiscible in the liquid state yet it has a higher melting point than that of pure water ice. A simple procedure is outlined for students to synthesize and study propane hydrate. This experiment introduces students to this unusual solid, while stimulating a discussion of the interplay of intermolecular forces, thermodynamics, and solid structure.
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| Supplement |
Detailed background information, student procedures, sample questions, and instructors notes, including drawings for fabricating the sample cells and a discussion of two component phase diagrams, are available.
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| More Information |
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Citation |
Prado, Melissa P.; Pham, Annie; Ferazzi, Robert E.; Edwards, Kimberly; Janda, Kenneth C. J. Chem. Educ. 2007, 84, 1790.
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Keywords |
Alkanes / Cycloalkanes; Applications of Chemistry; Calorimetry / Thermochemistry; Chemical Engineering; Environmental Chemistry; First-Year Undergraduate / General; Gases; Hands-On Learning / Manipulatives; High School / Introductory Chemistry; Hydrogen Bonding; Laboratory Instruction; Phases / Phase Transitions / Diagrams; Physical Chemistry; Problem Solving / Decision Making; Thermodynamics; Upper-Division Undergraduate; Water / Water Chemistry
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History |
Created:
Last Updated: |
9/19/2007
9/27/2007
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 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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