We will distinguish between the properties of a material in several different ways:
Measured properties are properties that are directly accessible in the laboratory. Examples include: temperature, pressure, volume
Fundamental properties are properties that are directly related to the fundamental laws of thermodynamics. These are internal energy and entropy (both will be discussed later).
Derived properties are specific relations that include combinations of measured and derived properties. Examples include enthalpy, Gibbs free energy.
Both fundamental and derived properties are unmeasurable