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  Home > JCE Print > Journal of Chemical Education > Issues > 1998  > March  >
In the Classroom
Applications and Analogies
A Closer Look at the Addition of Equations and Reactions
Damon Diemente
Trinity School, 101 West 91st Street, New York, NY 10024
Cover
March 1998
Vol. 75 No. 3
p. 319
Abstract
Chemists occasionally find it convenient or even necessary to express an overall reaction as the sum of two or more component reactions. We add chemical equations as if they were algebraic equations, even to the point of cancelling out terms (actually quantities of chemical reagents) that appear on both sides. This amounts to assuming that the plus sign has the same significance in both kinds of equations, and that the arrows we customarily use in chemistry are simply a variation on the equals sign with no significant difference in meaning. A close examination, however, reveals that the resemblance between chemical algebraic equations is entirely superficial, and that the real meaning of addition in chemical equations is subtle and varies from case to case. In high-school courses, students are likely to encounter the addition of equations in thermochemistry, in electrochemistry, and in kinetics. This article looks into a few examples drawn from these three branches of chemistry.

See Letter re: this article.
More Information
*  Citation
 Diemente, Damon. J. Chem. Educ. 1998 75 319.
*  Keywords
 Introductory/High School Chemistry, Calorimetry, Electrochemistry, Mechanisms, Stoichiometry
*  History
 Created:
Last Updated:		 June 28, 1999
June 24, 2005
Link to Letter added (April 2004).
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