Published: September 02, 2011

Copyright r 2011 American Chemical Society andDivision of Chemical Education, Inc. 1459 dx.doi.org/10.1021/ed2005328 | J. Chem. Educ. 2011, 88, 1459–1460

BOOK AND MEDIA REVIEW

pubs.acs.org/jchemeduc

Review of Molecular Driving Forces: Statistical Thermodynamics inBiology, Chemistry, Physics, and Nanoscience, 2nd editionAddison Ault*

Department of Chemistry, Cornell College, Mount Vernon, Iowa 52314, United States

Molecular Driving Forces: Statistical Thermodynamicsin Biology, Chemistry, Physics, and Nanoscience, 2ndedition by Ken A. Dill and Sarina Bromberg. GarlandScience: New York, 2010. 756 pp. ISBN: 978-081534430-8(paper). $140.00.

In the preface to this second edition of Molecular DrivingForces, the authors ask, “What forces drive atoms and moleculesto bind, to permeate membranes, to undergo chemical reactions,and to undergo conformational changes?” They then add that“This text is intended for graduate students and advancedundergraduates in physical chemistry, biochemistry, biophysics,bioengineering, polymer and materials science, pharmaceuticalchemistry, chemical engineering, and environmental science.”

Cover image provided byGarland Science and reproducedwith permission.

The final sentence of the preface is:

For those familiar with the First Edition, this SecondEditionincludes three new chapters: (1) “Microscopic Dynamics”describes themicroscopic basis for dynamical processes andsingle-molecule processes; (2) “Molecular Machines” de-scribes hownanoscalemachines and engines work, and howenergy is transduced into actions; and (3) “The Logic ofThermodynamics” was added in response to requests fromusers of the first edition to describe more of classicalthermodynamics, including more details on the distinctionbetween reversible and irreversible processes.

Wemight outline the book in this way. The title of Chapter 1 isPrinciples of Probability, and the first sentence of this chaptersays that the principles of probability are the foundations ofentropy. We see in Chapter 2 on page 32 the statement thatmaximizingmultiplicity predicts themost probable outcome, and

then on page 52 we find that the answer to the question—whydoes heat flow?—is that “[T]he flow of heat from hot to coldobjects is also driven by a tendency tomaximize multiplicity.”Webegin to suspect that it is all about multiplicity, and our suspicionsare confirmed by reading on page 55 that “All these tendenciesare predicted by a principle of maximum multiplicity: A systemwill change its degrees of freedom to reach the microscopicarrangement with the maximum possible multiplicity”.

It may be helpful here to recall Feynman’s words aboutmultiplicity:1 “We measure “disorder” [entropy; multiplicity]by the number of ways that the insides can be arranged so thatfrom the outside it looks the same.” The look of the “outside” isdescribed by the pressure, volume, temperature, energy, andentropy of the system, and the “insides”, or microstates, are thecombinations of particles with energies that satisfy a pair ofconditions. The two conditions, or “constraints”, are (i) thenumber of particles must equal the number of particles of thesystem, and (ii) the energies of the particles must equal thethermal energy of the system.

When a system actually meets these conditions, it will be asystem at equilibrium, and the distribution of energies overparticles will be a Boltzmann distribution. If a system does notmeet these conditions, it will be a system that is not atequilibrium and it will eventually evolve to become a systemthat has a Boltzmann distribution. The reason that the systemwillevolve to become a systemwith a Boltzmann distribution is that aBoltzmann distribution is so very much more highly probablethan any other distribution. Actually, a Boltzmann distribution isso much more highly probable than any other distribution thatevolution to a Boltzmann distribution is inevitable. This evolu-tion is the molecular driving force, and the rest of the book is,essentially, a discussion of how multiplicity is maximized undervarious circumstances.

Molecular Driving Forces is beautifully illustrated with a greatvariety of very helpful illustrations, graphs, and diagrams. Thisundoubtedly stems from the unique backgrounds and expertiseof both of the authors: Ken Dill received his undergraduatetraining at MIT, his Ph.D. from the University of California, SanDiego, and did postdoctoral work at Stanford; Sarina Brombergreceived her BFA at the Cooper Union for the Advancementof Science and Art, her Ph.D. in molecular biophysics fromWesleyan University, and her postdoctoral training at theUniversity of California, San Francisco.

The book also offers remarkably imaginative examples of com-plex ideas taken from everyday life. For example, the Smoluchowski

1460 dx.doi.org/10.1021/ed2005328 |J. Chem. Educ. 2011, 88, 1459–1460

Journal of Chemical Education BOOK AND MEDIA REVIEW

equation that describes particles driven by both applied forcesand diffusion is compared to a horse race. The peak of thedistribution moves toward the finish line with velocity, v, but thevariance of the distribution increases with time. “It is only approxi-mate for horse races, which usually have only small numbers ofhorses.”

Most chapters end with sections called Summary, Problems,References, and Suggested Reading. The Problems are oftenextensions of points made in the text, or concern phenomenarelated to those mentioned in the text. I believe this book willbe considered among the classics in chemistry, along withHammett’s Physical Organic Chemistry2,3 and Jencks’ Catalysisin Chemistry and Enzymology.4

’AUTHOR INFORMATION

Corresponding Author*E-mail: aault@cornellcollege.edu.

’REFERENCES

(1) Feynman, R. P. Order and Entropy. In Feynman Lectures onPhysics (Vol. I, Section 46�5); Addison-Wesley Pub. Co.: Reading, MA,1963.(2) Hammett, L. P. Physical Organic Chemistry; McGraw Hill:

New York, 1940.(3) Hammett, L. P. Physical Organic Chemistry, 2nd ed.; McGraw

Hill: New York, 1970.(4) Jencks, W. P. Catalysis in Chemistry and Enzymology; McGraw

Hill: New York, 1969.