11. This fugacity is approximately equal to the vapor pressure when the vapor pressure is not too high. 12. For gases, the activity is the effective partial pressure, and is usually referred to as fugacity . 13. For an ideal gas, fugacity and pressure are equal so " ? " is 1. 14. Fugacity is used to better approximate the chemical potential of real gases than estimations made using the ideal gas law.15. It can also be used to calculate the fugacity of oxygen recorded by mineral assemblages in metamorphic and igneous processes. 16. Redox buffers were developed in part to control oxygen fugacities in laboratory experiments to investigate mineral stabilities and rock histories. 17. Each of the curves plotted in the fugacity -temperature diagram is for an oxidation reaction occurring in a buffer. 18. For nitrogen at 100 atm, the fugacity coefficient is 97.03 atm / 100 atm = 0.9703. 19. Frequently, the fugacity of the pure liquid is used as a reference state when defining and using mixture activity coefficients. 20. There are numerous extra factors to consider such as oxygen fugacity and water activity ( roughly, the same as concentration ).
