Preface - Liquid-State Physical Chemistry: Fundamentals, Modeling, and Applications (2013)

Liquid-State Physical Chemistry: Fundamentals, Modeling, and Applications (2013)


For many processes and applications in science and technology a basic knowledge of liquids and solutions is a must. However, the usual curriculum in chemistry, physics, and materials science pays little or no attention to this subject. It must be said that many books have been written on liquids and solutions. However, only a few of them are suitable as an introduction (many of them are far too elaborate), and most of them have been published quite some time ago, apart from the relatively recent book by Barrat and Hansen (2005). In spite of my admiration for that book I feel that it is not suitable as an introduction for chemical engineers and chemists.

In the present book a basic but as far as possible self-contained and integrated treatment of the behavior of liquids and solutions and a few of their simplest applications is presented. After introducing the fundamentals required, we try to present an overview of models of liquids giving an approximately equal weight to pure liquids, simple solutions, be it non-electrolyte, electrolyte, or polymeric solutions. Thereafter, we deal with a few special topics: reactions in solutions, surfaces, and phase transitions. Obviously, not all topics can be treated and a certain initial acquaintance with several aspects of physical chemistry is probably an advantage for the reader.

A particular feature of this book is the attempt to provide a basic but balanced presentation of the various aspects relevant to liquids and solutions, using the regular solution concept as a guide. That does not imply that we “forget” more modern approaches, but the concept is useful as a guide, in particular for engineering applications. To clarify the authors' view on the subject a bit further, it may be useful to quote Henry Eyrings' statement, as printed on the title page, more fully:

There are two quite different approaches to a theory of the liquid state which in fact complement each other. In the deductive approach one proceeds as far as possible strictly mathematically, and when the complications cause this logical procedure to bog down, one resorts to some more or less defensible assumption such as Kirkwood's superposition principle. In the other approach one struggles to find a physical model of the liquid state which is as faithful to reality as can be devised and yet be solvable. The solution of the model may then proceed with considerable rigor. There are advantages and disadvantages to both procedures. In fact, either method expertly enough executed will solve the problem.

Although rigorous approaches have advanced considerably since the time this statement was made, the essence of this remark is still to the point in our view, in spite of the rebuttal by Stuart Rice:

The second approach mentioned by professor Eyring depends on our ability to make a very accurate guess about the structure and proper parameterization of the model or models chosen. It is the adequacy of our guesses as representations of the real liquid which I question.

There is no doubt that rigorous approaches are important, much more so than in the time Eyring made his remark but, in our opinion, understanding is still very much served by using as simple as possible models.

The whole of topics the presented is conveniently described as physical chemistry or the chemical physics1) of liquids and solutions: it describes the physico-chemical behavior of liquids and solutions with applications to engineering problems and processes. Unfortunately, this description is wide, in fact too wide, and we have to limit ourselves to those topics that are most relevant to chemical engineers and chemists. This implies that we do not deal systematically with quantum liquids, molten salts, or liquid metals. Obviously, it is impossible to reflect these considerations exactly in any title so that we have chosen for a brief one, trusting that potential users will read this preface (and the introduction) so that they know what to expect. For brevity, therefore, we refer to the field as liquid-state physical chemistry.

We pay quite some attention to physical models since, despite all developments in simulations, they are rather useful for providing a qualitative understanding of molecular liquids and solutions. Moreover, they form the basis for a description of the behavior of polymer solutions as presently researched, and last – but not least – they provide to a considerable extent solvable models and therefore have a substantial pedagogical value. Whilst, admittedly, this approach may be characterized by some as “old-fashioned,” in my opinion it is rather useful.

This book grew out of a course on the behavior of liquids and solutions, which contained already all the essential ingredients. This course, which was conducted at the Department of Chemical Engineering and Chemistry at Eindhoven University of Technology, originated from a total revision of the curriculum some 10 years ago and the introduction of liquid-state physical chemistry (or as said, equivalently, liquid-state chemical physics) some seven years ago. The overall set-up as given here has evolved during the last few years, and hopefully both the balance in topics and their presentation is improved. I am obliged to our students and instructors who have followed and used this course and have provided many useful remarks. In particular, I wish to thank my colleagues Dr Paul van der Varst, Dr Jozua Laven, and Dr Frank Peters for their careful reading of, and commenting on, several parts of the manuscript, and their discussions on many of the topics covered. Hopefully, this has led to an improvement in the presentation. I realize that a significant part of writing a book is usually done outside office hours, and this inevitably interferes considerably with one's domestic life. This text is no exception: for my wife, this is the second experience along this line, and I hope that this second book has “removed” less attention than the first. I am, therefore, indebted to my wife Ada for her patience and forbearance. Finally, I would like to thank Dr Martin Graf-Utzmann (Wiley-VCH, publisher) and Mrs Bernadette Cabo (Toppan Best-set Premedia Limited, typesetter) for all their efforts during the production of this book.

Obviously, the border between various classical disciplines is fading out nowadays. Consequently, it is hoped that these notes are useful not only for the original target audience, chemists, and chemical engineers, but also for materials scientists, mechanical engineers, physicists, and the like. Finally, we fear that the text will not be free from errors, and these are our responsibility. Hence, any comments, corrections, or indications of omissions will be appreciated.

Gijsbertus de With

January 2013


1) I refer here to the preface of Introduction to Chemical Physics by J.C. Slater (1939), where he states: “It is probably unfortunate that physics and chemistry were ever separated. Chemistry is the science of atoms and the way they combine. Physics deals with the interatomic forces and with the large-scale properties of matter resulting from those forces. … A wide range of study is common to both subjects. The sooner we realize this, the better”.