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ERIC Number: EJ936772
Record Type: Journal
Publication Date: 2011-May
Pages: 3
Abstractor: As Provided
Reference Count: 11
ISBN: N/A
ISSN: ISSN-0021-9584
Gibbs Energy Changes during Cobalt Complexation: A Thermodynamics Experiment for the General Chemistry Laboratory
DeGrand, Michael J.; Abrams, M. Leigh; Jenkins, Judith L.; Welch, Lawrence E.
Journal of Chemical Education, v88 n5 p634-636 May 2011
By adding a large quantity of Cl[superscript -] to an aqueous solution of CoCl[subscript 2][multiplied by]6H[subscript 2]O, a mixture containing a red octahedral cobalt complex and a blue tetrahedral complex is produced. When the solution temperature is modified, the equilibrium constant, K[subscript eq], of the complexation reaction is shifted and the proportion of the two colored forms altered correspondingly. Absorbance spectrophotometry is utilized to determine the concentration of each cobalt species, allowing K[subscript eq] and the change in Gibbs energy, deltaG[degrees], values to be found at each temperature tested. By plotting deltaG[degrees] versus temperature, the changes in entropy and enthalpy for the reaction can be determined. (Contains 2 tables and 2 figures.)
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