Page 17 - Physical chemistry understanding our chemical world

xvi PREFACE

of kinetics (Chapter 8); and the energetics of chemical reactions (Chapters 2–4). The
sensations of taste and sight are ultimately detected within the brain as electrical
impulses, which we explain from within the rapidly growing field of electrochemistry
(Chapter 7). Even the way a nut sticks to our teeth is readily explained by adsorption
science (Chapter 10). Truly, the whole of physical chemistry can be encompassed
within a few everyday examples.
So the approach taken here is the opposite to that in most other books of physical
chemistry: each small section starts with an example from everyday life, i.e. both the
world around us and also those elementary observations that a chemist can be certain
to have pondered upon while attending a laboratory class. We then work backwards
from the experiences of our hands and eyes toward the cause of why our world is
the way it is.
Nevertheless, we need to be aware that physical chemistry is not a closed book in
the same way of perhaps classical Latin or Greek. Physical chemistry is a growing
discipline, and new experimental techniques and ideas are continually improving the
data and theories with which our understanding must ultimately derive.
Inevitably, some of the explanations here have been over-simplified because phys-
ical chemistry is growing at an alarming rate, and additional sophistications in theory
and experiment have yet to be devised. But a more profound reason for caution is
in ourselves: it is all too easy, as scientists, to say ‘Now I understand!’ when in fact
we mean that all the facts before us can be answered by the theory. Nevertheless, if
the facts were to alter slightly – perhaps we look at another kind of nut – the theory,
as far as we presently understand it, would need to change ever so slightly. Our
understanding can never be complete.
So, we need a word about humility. It is said, probably too often, that science is
not an emotional discipline, nor is there a place for any kind of reflection on the
human side of its application. This view is deeply mistaken, because scientists limit
themselves if they blind themselves to any contradictory evidence when sure they
are right. The laws of physical chemistry can only grow when we have the humility
to acknowledge how incomplete is our knowledge, and that our explanation might
need to change. For this reason, a simple argument is not necessary the right one; but
neither is a complicated one. The examples in this book were chosen to show how
the world around us manifests Physical Chemistry. The explanation of a seemingly
simple observation may be fiendishly complicated, but it may be beautifully simple. It
must be admitted that the chemical examples are occasionally artificial. The concept
of activity, for example, is widely misunderstood, probably because it presupposes
knowledge from so many overlapping branches of physical chemistry. The examples
chosen to explain it may be quite absurd to many experienced teachers, but, as
an aid to simplification, they can be made to work. Occasionally the science has
been simplified to the point where some experienced teachers will maintain that it is
technically wrong. But we must start from the beginning if we are to be wise, and
only then can we progress via the middle ... and physical chemistry is still a rapidly
growing subject, so we don’t yet know where it will end.
While this book could be read as an almanac of explanations, it provides students
in further and higher education with a unified approach to physical chemistry. As a