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  Home > JCE Print > Journal of Chemical Education > Issues > 1997  > August  >
Chemistry Everyday for Everyone
Why Don't Things Go Wrong More Often? Activation Energies: Maxwell's Angels, Obstacles to Murphy's Law
Frank L. Lambert
2834 Lewis Dr., La Verne, CA 91750
Cover
August 1997
Vol. 74 No. 8
p. 947
Abstract
Students often invoke Murphy's Law when inanimate "things go wrong", when skis break or fires occur or instruments fail due to corrosion or tires unexpectedly wear out. But why don't similar upsetting events happen to everyone every minute? Unwanted combustion and corrosion of common materials, although energetically favored, are not kinetically instantaneous. (The second law of thermodynamics is time's arrow but chemical kinetics is time's clock.) Chemistry students learn that chemical changes are usually obstructed by activation energy barriers whose origins lie in the energy required for bond breaking as new bonds are formed. Thus, activation energies act as obstacles to Murphy's Law in being deterrents to undesirable reactions and, lightly, as our "Maxwell's Angels". The fracture of solids - whether surfboards or car fenders - also involves breaking chemical bonds. However, such incidents are classed as physical changes because the free energy of the fragments is not notably different from the unbroken whole. The micro-complexity of fracturing utilitarian or beautiful objects prevents assigning a characteristic activation energy even to chemically identical artifacts. Nevertheless, a qualitative EACT SOLID can be developed. Its surmounting is correlated with the radical drop in human valuation of an object when it is broken.
More Information
*  Citation
 Lambert, Frank L. J. Chem. Educ. 1997 74 947.
*  Keywords
 Physical Chemistry, Public Understanding/Appreciation, Kinetics, Non-major courses, Thermodynamics
*  History
 Created:
Last Updated:		 July 28, 1999
June 23, 2005
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