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ELECTROCHEMISTRY 27

polluted water does not matter. By flowing wastewater through an electrochemical
reactor of this type, impurities are reduced about a thousand times.

1.12. SCIENCE, TECHNOLOGY, ELECTROCHEMISTRY, AND TIME

1.12.1. Significance of Interfacial Charge-Transfer Reactions

It is informative in this chapter to make some attempt to place electrochemistry
among the sciences and obtain the relative measure of its significance. It is difficult to
do this for a field, the modern phase of which dates back only 50 years. Let us try, but
let us realize that what we are doing here is speculating, although we will give some
of the reasoning that supports our conclusions.
First, we can ask a relative question: Is interfacial electrochemistry simply a
special aspect of reaction kinetics, somewhat analogous to photochemistry? In photo-
chemistry, one might say, one studies the effect of energy packets (photons) striking
molecules; in electrochemistry, one studies the effect of striking molecules dissolved
in solution with electrons emitted from electrically charged conductors.
Or does interfacial electrochemistry have a greater significance? The evidence for
tending to this latter view is as follows:

1. Interfacial electrochemistry has a high degree of prevalence in the practical
world compared with other branches of knowledge outside physics. A way to appre-
ciate this is to realize how often one is concerned with electrochemical phenomena
outside the laboratory. For example, one starts a car and listens to its radio on battery
power; television pictures are transmitted from space vehicles to the earth by fuel-cell
power; a sports car may be made of electrochemically extracted aluminum; the water
that is in one’s coffee may be obtained by electrochemical deionization from impure
or brackish water; some persons ride in electrically powered cars; one wears clothes
of nylon produced from adiponitrile, which is electrochemically synthesized; one adds
an inhibitor to the radiator fluid of a car to reduce electrochemical corrosion. Finally,
one thinks by using electrochemical mechanisms in the brain, and one’s blood remains
liquid as long as the electrochemical potential at the interface between the corpuscles
and their solution remains sufficiently high and of the same sign.
2. This ubiquitous role for electrified interfaces throughout many aspects of
science suggests that electrochemistry should not be regarded as only a branch of
chemistry. Rather, while most chemists have concentrated upon thermally activated
reactions and their mechanisms, with electrochemical reactions as some special
academic subcase, there is a parallel type of chemistry based not on the collisions of
molecules and the energy transfers that underlie these collisions but on interfacial
electron transfers. It is this latter chemistry that seems to underlie much of what goes
on in the world around us, for example, in photosynthesis, in metabolism, and in the