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ERIC Number: EJ838946
Record Type: Journal
Publication Date: 2009-Jan
Pages: 5
Abstractor: As Provided
Reference Count: 24
ISBN: N/A
ISSN: ISSN-0021-9584
The Correlation of Standard Entropy with Enthalpy Supplied from 0 to 298.15 K
Lambert, Frank L.; Leff, Harvey S.
Journal of Chemical Education, v86 n1 p94-98 Jan 2009
As a substance is heated at constant pressure from near 0 K to 298 K, each incremental enthalpy increase, dH, alters entropy by dH/T, bringing it from approximately zero to its standard molar entropy S degrees. Using heat capacity data for 32 solids and CODATA results for another 45, we found a roughly linear relationship between S degrees and deltaH degrees. The plot showing the relationship S degrees is approximately equal to (constant) deltaH degrees, with constant = 0.0066 K[superscript -1], for 77 solids can serve as an enlightening visualization of this relationship for students in general chemistry. The near-linearity can be understood qualitatively in terms of lattice vibrations and internal vibrations within polyatomic units, which are reflected by molar heat capacities and Debye temperatures. This study supports the thesis that thermodynamic entropy and stored internal energy in a solid are intimately related and that entropy can be usefully interpreted as a spreading function, as described in the text. (Contains 4 figures, 1 table, and 11 notes.)
Division of Chemical Education of the American Chemical Society. Subscription Department, P.O. Box 1267, Bellmawr, NJ 08099-1267. Tel: 800-691-9846; Tel: 856-931-5825; Fax: 856-931-4115; e-mail: jchemed@egpp.com; Web site: http://www.jce.divched.org
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: California