In this Demonstration, standard molar enthalpies, heat capacities, and entropies for 20 common gas molecules are computed by the methods of statistical thermodynamics. The temperature of each gas can be varied from its boiling temperature to 1000K. The calculated thermodynamic functions are accurate to within 0.1 and 0.5% of the corresponding experimental values. The molecuar weight should rigorously refer to a specific isotopic species but little error is made by using the chemical value . You can also show plots of these thermodynamic functions over the temperature range from the boiling point to 1000K.