ERIC Number: EJ918272
Record Type: Journal
Publication Date: 2010-Jun
Pages: 4
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0021-9584
EISSN: N/A
Vapor Pressure Plus: An Experiment for Studying Phase Equilibria in Water, with Observation of Supercooling, Spontaneous Freezing, and the Triple Point
Tellinghuisen, Joel
Journal of Chemical Education, v87 n6 p619-622 Jun 2010
Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature to [approximately]-20 [degrees]C, and temperature and pressure are recorded on warm-up, first for sublimation, then vaporization, with a pronounced halt at the triple point. Analysis of the data by the integrated Clausius-Clapeyron equation typically yields [delta][subscript sub]H[subscript m] and [delta][subscript vap]H[subscript m] values within [approximately]2% (1 kJ/mol) of literature, from which [delta][subscript fus]H[subscript m] can also be estimated with fair precision. The experiment is designed for the undergraduate physical chemistry teaching laboratory; aspects of it are also appropriate for demonstrations in general and physical chemistry courses. (Contains 5 figures.)
Descriptors: Chemistry, Climate, Science Instruction, Teaching Methods, College Science, Undergraduate Study, Science Laboratories, Scientific Concepts, Equations (Mathematics), Science Experiments
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A