The Fundamental Equations Closed Systems

If we are to determine thermodynamic properties from the physical ones, the appropriate relationships between these two types of properties must be established. These relationships are referred to as fundamental equations, for they contain all the information needed for the complete description of the state of a system. 

We will start our discussion with closed systems, i.e. systems that do not exchange mass with the surroundings and, consequently, their mass is constant, and then consider - in the next Section - open systems, i.e. systems of variable mass. 

Because the approach for developing the hindamental equations is basically the same for mixtures and pure compounds, we will discuss the more general case of mixtures. 

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