Standard Molar Quantities of a Gas

Here B is the second virial coefficient, a function of T. With this equation of state, Eq. 7.8.16 becomes 

For areal gas at temperature T and pressure / , Eq. 7.8.16 or 7.8.18 allows us to evaluate the fugacity coefficient from an experimental equation of state or a second virial coefficient. We can then find the fugacity from / = (pp. 

The dependence of the chemical potential on pressure at constant temperature is given by Eq. 7.8.5. With an approximation of zero compressibility, this becomes 

A standard molar quantity of a substance is the molar quantity in the standard state at the temperature of interest. We have seen (Sec. 7.7) that the standard state of a pure liquid or solid is a real state, so any standard molar quantity of a pure liquid or solid is simply the molar quantity evaluated at the standard pressure and the temperature of interest. 

The standard state of a gas, however, is a hypothetical state in which the gas behaves ideally at the standard pressure without influenee of intermolecular forces. The properties of the gas in this standard state are those of an ideal gas. We would like to be able to relate molar properties of the real gas at a given temperature and pressure to the molar properties in the standard state at the same temperature. 

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CHAPTER 7 PURE SUBSTANCES IN SINGLE PHASES 7.9 Standard molar Quantities of a Gas... 

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