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The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 12 Issue 2 (2007) pp 85-88

Chemical Flags: Red, White, Blue, and Beyond

Jeff M. Reising, Phuong N. Nguyen, Edward B. Flint and Dean J. Campbell*

Department of Chemistry and Biochemistry, Bradley University, Peoria, IL 6162,
Received August 21, 2006. Accepted March 4, 2007.

Published online: 1 April 2007

Abstract. Dramatic color-changing displays, where a reagent is added to clear solutions to produce brightly colored patterns, are described for use on an overhead projector or document camera. Based on the classic “Red, White, and Blue” demonstration, where ammonia is added to beakers containing phenolphthalein, lead(II) acetate, and copper(II) nitrate, we have adapted this as a projection display using 96-well plates and automatic pipettes. The two-dimensional nature of the 96-well plates enables the production of interesting patterns, such as flags, words, logos, etc. The color-changing reagent can be added as a liquid from a wash bottle, as an aerosol from a spray bottle, as a gas from a concentrated solution, or most conveniently as a solid, which needs to be sieved to an appropriate size. The best display is made by adding solid NH4SCN to solutions of Fe3+(red), Ag+(white), and Co2+ in alcohol (blue).

Key Words: Laboratories and Demonstrations; general chemistry

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Issue date: April 1, 2007

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