Reversible process entropy criteria

The method developed here is in many ways analogous to that employed by Schottky, Ulich and Wagner. Both methods emphasize the criterion for establishing the irreversibility of a chemical reaction and for deciding whether the reaction will proceed spontaneously in a particular direction. In De Bonder s method this criterion appears immediately the production of entropy must be positive. On the other hand Schottky, Ulich and Wagner employ as the criterion of irreversibility the loss of useful work associated with the real process when compared with a hypothetical reversible process. As is shown in chap. V, these criteria are equivalent for isothermal changes. For non-isothermal changes, however, the concept of loss of useful work... 

In Section 13.5, we showed that the change in entropy of a system plus its surroundings (that is, the total change of entropy, AStoJ provides a criterion for deciding whether a process is spontaneous, reversible, or impossible ... 

Processes An Introduction— A process that proceeds without external intervention is said to be a spontaneous process. A nonspontaneous process cannot occur without external intervention. If a process is spontaneous in one direction, then it is nonspontaneous in the reverse direction. Some spontaneous processes are exothermic, and others are endothermic, so the criterion for spontaneous change cannot be based on enthalpy changes alone. The direction of spontaneous change involves changes in another property called entropy. Entropy provides a measure of the number of ways a given quantity of energy can be dispersed, or distributed, among the particles of the system. 

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