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  Home > JCE Print > Journal of Chemical Education > Issues > 2009  > July  >
In the Classroom
JCE DigiDemos: Tested Demonstrations
Marangoni Flowers and the Evil Eye: Overhead Presentations of Marangoni Flow
Donald W. Mundell
Department of Chemistry, Owensboro Community and Technical College, Owensboro, KY 42303
Cover
July 2009
Vol. 86 No. 7
p. 833

Abstract
Intermolecular forces and surface tension gradients in solutions lead to remarkable flows, known as Marangoni flows, where liquid flows from a region of low surface tension towards higher surface tension. Details of these flows, not visible to the naked eye, are made visible on an overhead projector owing to variation in the index of refraction. The demonstrations use Marangoni effects to create images on the overhead projector simulating flowers, an evil eye, and a Zen garden. In the evil eye and the Zen garden demonstrations, the combined effects of surface tension and adhesive forces become more apparent as the solution pulls away from a glass piece revealing a thin layer of Marangoni flow surrounded by solution. The ideas behind these surface tension flows solidify understanding of intermolecular forces and lead to a discussion of intermolecular forces, properties of liquids, surface tension, and Marangoni effects. Video presentations of the demonstrations are available in the online material.

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Supplement
Videos of the demonstrations; PowerPoint presentation
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Contents
More Information
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Citation
Mundell, Donald W. J. Chem. Educ. 2009, 86, 833.
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Keywords
Alcohols; Demonstrations; First-Year Undergraduate / General; Hands-On Learning / Manipulatives; High School / Introductory Chemistry; Hydrogen Bonding; Liquids; Molecular Properties / Structure; Physical Chemistry; Physical Properties; Solutions / Solvents; Surface Science; Upper-Division Undergraduate
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History
Created:
Last Updated:
6/1/2009
6/9/2009
 Caution! 
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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