Fugacity

The fugacity is defined differently depending on the subject area.

Definition from statistical physics

In statistical physics, which forms the basis of thermodynamics, the fugacity is defined as a dimensionless function of the chemical potential and the temperature:

With

  • - The Boltzmann constant.

The fugacity is emerging as a factor in the transition from the canonical partition function, which describes systems with constant number of particles, the grand canonical partition function, which is suitable for the description of systems with variable number of particles:

Definition from thermodynamics

In thermodynamics, the fugacity can be interpreted as the effective (or corrected ) of an actual gas pressure, which is considered in the context of a pressure change:

The dimensionless factor is called the fugacity coefficient. He describes the deviation of the behavior of real gas from the ideal gas. It is pressure dependent: at very low pressures it approaches 1, at high pressures it may differ significantly from 1. see also: real gas factor

The fugacity as the pressure intense size and also has the unit of pressure, eg Pascal.

Essential for ideal gases applicable laws may be applied for real gases when in the equations the pressure (or partial pressure in gas mixtures ) are replaced by the fugacity. Particularly advantageous is the use of fugacity in the determination of the Gibbs free energy for the state of the real gas to the pressure change.

For more explanation

Another intuitive explanation is that the fugacity is the tendency of the molecule to leave the system indicates. This also explains the concept itself ( = expel ) from the Latin fugare.

See also: Volatility

355031
de