ERIC Number: EJ1028747
Record Type: Journal
Publication Date: 2013-Aug
Abstractor: As Provided
Reference Count: N/A
Why Are Some Reactions Slower at Higher Temperatures?
Revell, Laura E.; Williamson, Bryce E.
Journal of Chemical Education, v90 n8 p1024-1027 Aug 2013
It is well understood by most chemistry students at advanced undergraduate levels that chemical reactions generally follow the Arrhenius law of temperature dependence with positive activation energies, proceeding faster at elevated temperatures. It is much less widely known that the rates of some Arrhenius-compliant reactions are retarded by increasing the temperature and are therefore associated with negative activation energies. The few readily accessible explanations of this phenomenon are rather cursory and limited to enthalpic considerations relating to the relative activation energies and thermicities of the component elementary steps of the process. However, these explanations are incomplete and consequently counterintuitive. Here we provide the required augmentation via entropic considerations.
Descriptors: Thermodynamics, Science Instruction, Chemistry, College Science, Scientific Concepts, Undergraduate Study, Kinetics
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: firstname.lastname@example.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education
Authoring Institution: N/A