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The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 9 Issue 1 (2004) pp 39-41

Alternative Demonstrations of Slow Processes II: A Video Clip of One-Dimensional Waves in the Hypochlorite–Iodide–Water System

Vladimir M. Petruševski,* Marina Monkovic, and Metodija Najdoski

Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000 Skopje, Republic of Macedonia,
Received October 1, 2003. Accepted October 10, 2003.

Published online: 1 January 2004

Abstract. A chemical wave was initiated in a system (test tube) containing an aqueous gel of potassium iodide and starch by carefully pouring an excess of bleaching solution (aqueous solution of sodium hypochlorite) over it. A blue disk is formed immediately at the boundary surface, which propagates slowly downwards. Photos (a total of 240) were taken with a digital camera (one snapshot every 20 s), and they were linked to give a video clip that may be used as a time-saving alternative to the classical demonstration.

Key Words: Laboratories and Demonstrations; physical chemistry; general chemistry; chemical waves; eraser and pencil analogy; gel media; video clip

(*) Corresponding author. (E-mail:

Article in PDF format (204 KB) HTML format

Supporting Materials:


Supporting Materials:

A 40-s movie ( (9.40 MB) showing propagation of the chemical wave in a clamped test tube is available as supporting material.

Issue date: February 1, 2004

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