JCE Online Journal of Chemical EducationDivision of Chemical Education, American Chemical SocietyAmerican Chemical Society
 | Subscriptions  | Software Orders  | Support  | Contributors  | Advertisers  | 

JCE Print

JCE Digital Library

JCE Software

Only@JCE Online

About JCE


  Home > JCE Print > Journal of Chemical Education > Issues > 2007  > May  >
In the Classroom
JCE DigiDemos: Tested Demonstrations
An Iodine Fluorescence Quenching Clock Reaction
Richard B. Weinberg
Departments of Internal Medicine and Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157

checked by Mark Muyskens
Department of Chemistry and Biochemistry, Calvin College, Grand Rapids, MI 49546-4403

Cover
May 2007
Vol. 84 No. 5
p. 797

Abstract
A fluorescent clock reaction is described that is based on the principles of the Landolt iodine reaction but uses the potent fluorescence quenching properties of triiodide to abruptly extinguish the ultraviolet fluorescence of optical brighteners present in liquid laundry detergents. The reaction uses easily obtained household products. One variation illustrates the sequential steps and mechanisms of the reaction; other variations maximize the dramatic impact of the demonstration; and a variation that uses liquid detergent in the Briggs–Rauscher reaction yields a striking oscillating luminescence. The iodine fluorescence quenching clock reaction can be used in the classroom to explore not only the principles of redox chemistry and reaction kinetics, but also the photophysics of fluorescent pH probes and optical quenching.
More Information
*
Citation
Weinberg, Richard B. J. Chem. Educ. 2007, 84, 797.
*
Keywords
Acids / Bases; Consumer Chemistry; Demonstrations; Dyes / Pigments; Elementary / Middle School Science; General Public; Hands-On Learning / Manipulatives; High School / Introductory Chemistry; Iodine; Kinetics; Oxidation / Reduction; pH; Photochemistry; Physical Chemistry; Rate Law; Vitamins
*
History
Created:
Last Updated:
3/22/2007
4/6/2007
 Caution! 
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.
  Home > JCE Print > Journal of Chemical Education > Issues > 2007  > May  > Page 797


Subscriptions

JCE HS CLIC

Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.


Contributions Welcome
JCE welcomes your submission

Advertisers
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.

Be An Ambassador
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.