A thermodynamics caculation of specific enthalpy and entropy for gas H_2 near the critical state

The specific enthlpy and entropy for gas H 2 near the critical temperature (T c) has been calculated by using thermodynamics method and Benedict-Webb-Rubin(BWR) equation as well as the corresponding parameters. The parameters for the relationship equation between specific thermal capacity and temperature are also deduced. Comparing the calculation results with the experimental counterparts, one can find that the theoretical results are in good agreement with the experimental data when the system temperature is up T c or under T c but the pressure not higher than the critical pressure (P c). For the gas H 2 under T c and higher than P c, the errores between the calculated results and experimental values are obvious. It shows that gas H 2 in the condition has especial properties, which implies special treat is necessary.