An empirical equation of state for gases

A simple pressure-explicit empirical equation of state for gases is presented which contains five constants in addition to the gas constant. It has been applied to carbon dioxide, hydrogen and nitrogen. The equation gives good accuracy (with maximum errors slightly higher than 1%) for densities up to critical and for temperatures from slightly above critical up to very high values. Below critical temperature it can still be applied with reasonable accuracy to the vapor. Thermodynamic functions (internal energy, enthalpy and entropy) derived from this equation show simple form and satisfactory accuracy over a wide range of temperature and density.