Fundamental Questions About Entropy I. Definitions: Clausius Or Boltzmann?
Published 2010 · Chemistry
The expression of Boltzmann S = k In W differs in principle from the entropy as defined by Clausius because it is not strictly extensive. It becomes strictly extensive when the number W of all possible molecular arrangements is replaced by a normalized value - N A N B… where 1) the standardized probability that characterizes one particle A is the same for all the NA particles; 2) the possibilities for the particles of a given kind are considered separately from the possibilities of the particles of another kind. In contrast to W that characterizes the whole system, is a product of as many factors as there are particles of different kinds in the different phases. Examples are given for the entropy of mixing of mixed crystals and the entropy of expansion of real gases.