Maxwell Relations

Fundamental thermodynamic property relations for a fluid of constant composition are as follows:

   à I    à II    à III    à IV

Criterion of exactness for a differential expression:

If , then the total differnential of F is defined as

   à V


where, and

By further differentiation, we obtain


Since the order of differentiation in mixed second derivatives is immaterial, these equations give

   à VI

Equation VI serves as a criterion of exactness, when F is a function of x & y