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2001
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February
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In the Laboratory
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Exploring Phase Diagrams Using Supercritical Fluids. An Undergraduate Physical Chemistry Laboratory
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Steven G. Mayer and Jeremy M. Gach
Department of Chemistry, Susquehanna University, Selinsgrove, PA 17870
Evelyn R. Forbes and Philip J. Reid
Department of Chemistry, University of Washington, Seattle, WA 98195
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February 2001
Vol. 78 No. 2
p. 241
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| Abstract |
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We present a physical chemistry laboratory in which students explore phase behavior using subcritical and supercritical fluids. In this experiment, the pressure-dependent dielectric constant of carbon dioxide (CO2) is measured at four temperatures spanning the critical point. For subcritical CO2, the dielectric constant undergoes a striking increase with pressure during condensation, demonstrating the existence of a phase transition. In contrast, the dielectric constant of supercritical CO2 undergoes a systematic increase with pressure demonstrating the absence of a phase transition in the supercritical region. The experiment provides physical chemistry students with a variety of experiences. From a practical standpoint, it allows students to directly use and handle supercritical fluids. From a pedagogical standpoint, the laboratory allows students to develop a cohesive picture of subcritical and supercritical behavior, thereby providing a physical picture of the phenomena schematically depicted in a phase diagram.
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| Supplement |
The complete description of this experiment and supplemental materials are available.
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 Contents |
JCE2001p0241W.doc (MS Word 98, Mac)
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| Download |
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| More Information |
Citation |
Mayer, Steven G.; Gach, Jeremy M.; Forbes, Evelyn R.; Reid, Philip J. J. Chem. Educ. 2001 78 241.
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Keywords |
Laboratory Instruction; Liquids; Phase Transitions / Diagrams; Physical Chemistry
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History |
Created:
Last Updated: |
December 22, 2000
August 31, 2005
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| Home > JCE Print > Journal of Chemical Education > Issues >
2001
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February
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241
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