Parameter of State

(or thermodynamic property), a physical quantity that characterizes the state of a thermodynamic system. Examples of parameters of state are temperature, pressure, specific volume, magnetization, and electric polarization. A distinction is made between extensive parameters of state, which are proportional to the mass of the thermodynamic system, and intensive parameters of state, which are independent of the mass. The extensive parameters include volume, internal energy, entropy, enthalpy, Helmholtz free energy, and Gibbs free energy. Among the intensive parameters are pressure, temperature, concentration, and magnetic induction. Parameters of state are interrelated; thus the equilibrium state of a system can be unambigously determined by establishing the values of a limited number of the parameters.