State Functions

We use the continuum thermodynamic variables to describe the state of a system, e.g., a state function:

$$\input{equations/eq-state-1}$$ (02-1)

This simply says that there is a physical relationship between different quantities that one could measure in a system. Some relationships come from the specific properties of a material (material properties) and some follow from physical laws that are independent of the material (the laws of thermodynamics).