Extended irreversible thermodynamics and the quality of temperature and pressure

It is reiterated that without a Gibbs-Duhem equation no thermodynamic description of irreversible and reversible processes exists. It is shown with the help of Gibbs-Duhem equation of extended irreversible thermodynamics that the physical contents of intensive quantities, the temperature and the pressure, do not change in going from reversible to irreversible processes. This confirms well with the earlier demonstrations of Eu and Garcia-Colin.