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  Home > JCE Print > Journal of Chemical Education > Issues > 2006  > December  >
In the Classroom
JCE DigiDemos: Tested Demonstrations
A Kinetics Demonstration Involving a Green–Red–Green Color Change Resulting from a Large-Amplitude pH Oscillation
Brian W. Pfennig and Richard T. Roberts
Department of Chemistry, Ursinus College, Collegeville, PA 19426

checked by: Dean Campbell
Department of Chemistry, Bradley University, Peoria, IL 61625-0208

Cover
December 2006
Vol. 83 No. 12
p. 1804
Abstract
A chemical demonstration of a clock reaction involving red and green colors for the winter holiday season is reported. The system consists of oxidation–reduction reactions involving iodate, sulfite, and thiosulfate that experiences a large-amplitude spike in pH. A combination of suitable acid–base indicators is employed to effect the green–red–green color changes as the pH changes. The spike behavior can be monitored as a function of time using a pH meter. The pedagogical relevance of the demonstration is also discussed.
More Information
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Citation
Pfennig, Brian W.; Roberts, Richard T. J. Chem. Educ. 2006 83 1804.
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Keywords
Acids / Bases; Demonstrations; Dyes / Pigments; First-Year Undergraduate / General; Hands-On Learning / Manipulatives; High School / Introductory Chemistry; Inorganic Chemistry; Inquiry-Based / Discovery Learning; Kinetics; Oxidation / Reduction; Physical Chemistry
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History
Created:
Last Updated:
10/30/2006
10/31/2006
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Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations.
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