Reversible Processes Definition of Intensive Variables

In eontrast to entropy, heat is not a function of state. For heat change, it matters whether a process 1 — 2 is carried out reversibly or irreversibly. For a reversible proeess, that is, a process in which the system is always fully relaxed. 

Infinitesimally small changes imply infinitesimally small deviations from equilibrium and, therefore, reversibility. The term Sq in Equation 3.4 may then be replaced by T dS, which gives 

The other intensive variables may be expressed similarly as the change in energy per unit extensive property, nnder the appropriate conditions. 

4 INTRODUCTION OF OTHER FUNCTIONS OF STATE MAXWELL RELATIONS 

At equilibrium, implying that the intensive variables are constant throughout the system, Equation 3.8 may be integrated, which yields 

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