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Entropy, Reversible and Irreversible Processes

The usefulness of the concept of entropy and the Second Law depends on our ability to define entropy of a physical system in a calculable way. Using (3.3.3), if the entropy So of a reference or standard state is defined, then the entropy of an arbitrary state S% can be obtained through a reversible process that transforms the state 0 to the state X (Fig. 3.6). [Pg.84]

A process is reversible only in the limit of infinite slowness as perfect reversibility is approached, the speed of the process tends to zero. As Max Planck notes in his treatise [5, p. 86], Whether reversible processes exist in nature or not, is not a priori evident or demonstrable . But irreversibility, if it exists, has to be universal because a spontaneous decrease of entropy in one system could be utilized to decrease the entropy of any other system through appropriate interaction a spontaneous decrease of entropy of one system implies a spontaneous decrease of entropy of all systems. Hence, either all systems are irreversible, or none are. [Pg.85]

in most texts on thermodynamics, an irreversible transformation is usually identified by the Clausius inequality [Pg.86]

Clausius also stated the Second Law like this Uncompensated transformations can only be positive. [4, p.-247]. [Pg.86]

Perhaps Clausius hoped to, but did not, provide a way of computing N associated with irreversible processes. Nineteenth-century thermodynamics remained in the restricted domain of idealized reversible transformation and without a theory that related entropy explicitly to irreversible processes. Some expressed the view that entropy is a physical quantity that is spatially distributed and transported (e.g. Bertrand [7] in his 1887 text), but still no theory relating irreversible processes to entropy was formulated in the nineteenth century. [Pg.86]


See other pages where Entropy, Reversible and Irreversible Processes is mentioned: [Pg.84]    [Pg.85]    [Pg.87]    [Pg.91]   


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