Why chemical reactions happen

Why chemical reactions happen
James Keeler and Peter Wothers
Oxford: Oxford University Press 2003 | Pp 254 | ?16.99 (SB) | ISBN 0199249733
Reviewed by Jeremy Harvey

Increasing entropy is the driving force behind chemical transformations.

Like alchemy before it, chemistry is concerned with transforming one substance into another. Beautiful colour changes, deafening explosions, or, less spectacularly but perhaps more importantly, the preparation of a new material or pharmaceutical all result from chemical reactions. As well as trying to make new and useful molecules, chemists also want to understand why and how reactions happen, and this is the subject of this book.

Traditionally, physical chemistry textbooks for students starting a university chemistry course - roughly speaking, the category to which this book belongs - start out covering topics such as quantum theory and the structure of atoms, or the states of matter and properties of gases, or other things fairly remote from chemical reactions. They typically also involve quite a lot of calculus.

Keeler and Wothers’ aim is to be different in both respects. The first chapter shows, with minimal maths, that chemical reactions happen because they lead to an increase in the entropy of the universe. This increase, required by the second law of thermodynamics, occurs either because the products themselves are of higher entropy, or because the reaction is exothermic and causes greater disorder in the environment by heating it up. Using this snappy introduction as a basis to build upon and explore more deeply, the authors then discuss a range of topics in physical chemistry, including organic, inorganic and theoretical aspects, such as ionic bonding and lattice energies, molecular electronic structure, organic reaction mechanisms, and kinetics.

Perhaps due to the limited space available, I felt that some subjects were perhaps not explained clearly enough. However, the novel structure of the book, offering in just 200 pages many stimulating insights into a lot of (sometimes difficult) material usually taught in a different way, makes it an attractive purchase.