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

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

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, vladop@iunona.pmf.ukim.edu.mk
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: vladop@iunona.pmf.ukim.edu.mk)

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Supporting Materials:

A 40-s movie (s00897040752asm.zip) (9.40 MB) showing propagation of the chemical wave in a clamped test tube is available as supporting material.