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  Home > JCE Print > Journal of Chemical Education > Issues > 1997  > July  >
In the Classroom
Overhead Projector Demonstrations
The Use of Cut-Out Molecular Models on the Overhead Projector To Illustrate Stoichiometry and Limiting Reactants
Richard J. Kashmar
Department of Chemistry and Physics, Wesley College, 120 North State Street, Dover, DE 19901
Cover
July 1997
Vol. 74 No. 7
p. 791
Abstract
One problem that some chemistry students seem to have is the inability to conceptualize about and understand the particulate nature of matter. This has led to many misconceptions, including the failure to realize that chemical reactions actually do involve the rearrangement of reactant molecules to form product molecules, and that the process involves the breaking and reforming of chemical bonds. This paper illustrates a method of demonstrating reaction stoichiometry for simple reactions on the overhead projector, using easily constructed plastic circles to represent reacting atoms. The circles are used to form molecules on the overhead. The atoms are then physically rearranged on the overhead to form product molecules. This method is especially useful for visually illustrating the idea of the limiting reactant as the reactant that is consumed first in a reaction, therefore limiting the further formation of products.

See Letter re: this article.
More Information
*  Citation
 Kashmar, Richard J. J. Chem. Educ. 1997 74 791.
*  Keywords
 Demonstrations, Introductory/High School Chemistry, Stoichiometry, Teaching/Learning Aids
*  History
 Created:
Last Updated:		 July 28, 1999
June 23, 2005
Link to Letter added (May 2004).
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