ABSTRACT
In previous chapters, we have stressed that in nature energy tends to decrease while entropy tends to increase. A naive first consideration of any machine or process is that energy is needed to continue operation and we often overlook energy expended on various repair activities that are a form of entropy management. It becomes more obvious that entropy is a factor when one studies chemical processes that ‘‘should’’ occur based on energy considerations but nevertheless require some sort of a catalyst or other special conditions, which imply geometric constraints that overcome the natural tendency of randomness to increase. The value of DS is a change in a state variable but the path can be modified by special conditions such as the introduction of a catalytic surface, which allows reactants to meet side-by-side compared to random collisions in the gas phase. Josiah Willard Gibbs (1839-1903) was a foremost U.S. scientist (Figure 6.1) who made important advances in thermodynamics applying the new idea of ‘‘chemical potential’’ (DG=n) as a free energy per mole of a substance in phase diagrams and applied to equilibria. At the time of his work, few people understood it but it was later developed into the idea of free energy and greatly affected thinking, teaching, and problem solving in chemical engineering. Gibbs’ research used what was advanced mathematics in his time but remained at what we call ‘‘classical physics’’ today since he predated quantum mechanics. Gibbs is especially noteworthy in that he carried out research in the United States at a time when the turmoil of the U.S. Civil War and settling in the West were not as conducive to research as was the case in Europe in the late 1800s. However, Gibbs had spent a year each in Paris, Berlin, and Heidelberg and had written contact with foremost scientists in Europe. Gibbs also held the very first PhD in chemical engineering in the United States, awarded in 1863 from Yale University. Other scientists including Albert Einstein regarded Gibbs as a foremost founder of thermodynamics and a true genius. It is indeed humbling to realize that such pure thought by Gibbs, Boltzmann, and others was carried out for the first time without the same sort of support we have now in ‘‘the information age,’’ although scientists did study each other’s work. Truly we stand on the shoulders of intellectual giants!
