ABSTRACT
In this chapter, we consider the calculation of changes in internal energy, enthalpy, and entropy for a closed system undergoing a process between an initial equilibrium state at a pressure P 1 and temperature T 1 and a final equilibrium state at P 2 and T 2. The internal energy, enthalpy, and entropy are nonmeasurable properties. A preliminary consideration of Equations 4.7 and 4.9 shows that in order to make any progress, we must first eliminate the entropy from these equations.
