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Revisiting History: Encountering Iodine Then and Now. A General Chemistry Laboratory To Observe Iodine from Seaweed
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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.
Keywords (Audience):
High School / Introductory ChemistryKeywords (Domain):
DemonstrationsKeywords (Pedagogy):
Hands-On Learning / ManipulativesKeywords (Subject):
Applications of ChemistryTools
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- Received: August 03, 2009
ACS
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