ERIC Number: EJ936772
Record Type: Journal
Publication Date: 2011-May
Pages: 3
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0021-9584
EISSN: N/A
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.)
Descriptors: Thermodynamics, Chemistry, Scientific Concepts, Energy, Science Instruction, Science Laboratories, Science Experiments, Spectroscopy, Scientific Principles, College Science
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