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  Home > JCE Print > Journal of Chemical Education > Issues > 2009  > February  >
In the Laboratory
Revisiting History: Encountering Iodine Then and Now
A General Chemistry Laboratory To Observe Iodine from Seaweed
M. Farooq Wahab
Department of Mathematics and Basic Sciences, NED University of Engineering and Technology, Karachi 75270, Pakistan
Cover
February 2009
Vol. 86 No. 2
p. 206

Abstract
The history of the discovery of iodine is retold using brown-colored seaweed found commonly along the ocean shore. The seaweed is ashed at a low temperature and the iodides are extracted into boiling water. The iodides are oxidized in acidic medium. Solvent extraction of iodine by oxidation of iodides as well as simple aqueous extraction of iodide salts is done. Slight warming of the solution produces discernible violet vapors in an Erlenmeyer flask when seen against a white background. The origin of iodine’s name—discussed in the article—is proven in the laboratory experiment. More generally, this activity serves to increase students’ interest in analytical chemistry, as well as relationships among elements in the periodic table.
Supplement
Instructions for students; notes for instructors; commercial sources for kelp and other brown-colored seaweed
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Citation
Wahab, M. Farooq. J. Chem. Educ. 2009, 86, 206.
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Keywords
Applications of Chemistry; Demonstrations; First-Year Undergraduate / General; Hands-On Learning / Manipulatives; High School / Introductory Chemistry; History / Philosophy; Inquiry-Based / Discovery Learning; Iodine; Nonmetals; Oxidation / Reduction; Public Understanding / Outreach; Qualitative Analysis; Separation Science
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History
Created:
Last Updated:
1/5/2009
1/14/2009
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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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