Property Relations for Homogeneous Phases

Equations (1.2) and (5.12) axe here written dWrts = -Pd nV) Together tlrese tliree equations give  

All of the primary themrodynanric properties—P, V, T, U, and S—aie included in Eq. (6.1). Additional thenrrodynanric properties arise oirly by definition in relation to these priirrary properties. In Chap. 2 the enthalpy was defined as a matter of convenience by the equation  

Two additional properties, also defined for convenience, are the Helmholtz energy, 

Each of these defined properties leads directly to an equation like Eq. f(5. i). Upon multiplication by n, Eq. (2. ii)becomes  

Equations (6.4) tlirough (6.6) are subject to the same restrictions as Eq. (6.1). All are written for the entire mass of any closed system. 

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