What is fugacity equation?

The fugacity equation is a thermodynamic expression that relates the chemical potential of a substance in a non-ideal gas mixture to its partial pressure. It is given by:

f = Pexp[(v-b)/RT]φ

where f is the fugacity, P is the partial pressure, v is the molar volume, b is the excluded volume of the substance, R is the gas constant, T is the temperature, and φ is the fugacity coefficient.

The fugacity coefficient is a dimensionless parameter that accounts for the non-ideal behavior of the substance in the mixture. It depends on the composition, temperature, and pressure of the system and is usually determined experimentally or through theoretical models.

The fugacity equation is widely used in thermodynamics and process engineering to calculate the phase equilibria, chemical reactions, and transport properties of non-ideal gas mixtures. It is also used in environmental and atmospheric sciences to model the behavior of pollutants in the atmosphere.