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Intense study of oscillating chemical reactions and
nonlinear dynamics in chemistry is only about 30 years old,
but there has been enormous progress in understanding
this fascinating and important area of chemistry. This advance
was triggered in the 1960s by two nearly simultaneous
developments. The first was Ilya Prigogine's theory of
dissipative structures (an early form of complexity theory). The
second was the discovery, with later mechanistic elucidation by
Field, Köros, and Noyes, of an unequivocal chemical example,
the cerium-ion-catalyzed oxidation of
CH2(COOH)2 by
BrO3- (the
Belousov-Zhabotinsky reaction), in which oscillations
in [Br-] and in
[CeIV]/[CeIII] are easily observed. This book is
a comprehensive overview of the area and covers basic
chemistry, underlying theory, experimental methods, and applications.
The idea of oscillating chemical reactions did not
find ready acceptance. It is our observation, formalized by
the second law of thermodynamics, that all spontaneously
occurring processes must be accompanied by an increase in
the entropy of the universe. However, in a spontaneously
reacting chemical system this means only that certain species, referred
to as reactants, must always monotonically disappear, while
other species, referred to as products, must always
monotonically appear. The concentrations of intermediate species, both
produced and consumed in the course of the chemical
reaction and present at concentrations much smaller than those of
the principal reactants, may indeed execute complex,
nonmonotonic behavior, but it must be driven by the entropy
increase of the overall conversion of reactants to products. Thus, in
a well-stirred system, intermediate concentrations may
exhibit multiple steady states, excitability, steady-state
instability, temporal oscillations, and even deterministic chaos, and
in an unstirred system, they may exhibit traveling waves
or stationary patterns in space. The requirements for the
occurrence of these behaviors are that the system be
maintained far from equilibrium and that the governing dynamic
equations be both nonlinear (i.e., contain terms such as
kixy or
kjx2) and possess suitable feedback loops, often related
to activator-inhibitor interactions or to autocatalytic
generation of intermediates.
The major strength of this treatment by Epstein
and Pojman is a strong connection between theory and
experiment. The mechanisms of many oscillating chemical reactions
are described in detail. This leads into the mathematics of
their governing nonlinear differential equations (e.g., simple
stability and bifurcation theory, together with the dynamic
structure necessary for a system to exhibit nonmonotonic behavior).
Descriptive topics, such as the systematic design and
major classes of chemical oscillators (e.g., the
BrO3-- and
ClO2--driven systems in open and closed reactors) are coupled
with a careful description of experimental methods. Also
included are recipes for demonstrations and undergraduate
laboratory experiments, useful computational and simulation tools
in chemical kinetics, and a sense of applications of these
new ideas in biology and chemical technology--for
example, polymerization processes and mixing and coupling effects
in chemical reactors.
This book belongs within easy reach of any person
either working in the area or in daily contact with people,
especially students, who nowadays hear of these topics from
many sources and who wish to learn more about them.
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