fugacity, f, p ˜

Of a substance B, f B or p B ˜, in a gaseous mixture is defined by f B = λ B lim p → 0 p B λ B, where p B is the partial pressure of B and λ B its absolute activity.
Source:
Green Book, 2nd ed., p. 50
See also:
PAC, 1994, 66, 533 (Standard quantities in chemical thermodynamics. Fugacities, activities and equilibrium constants for pure and mixed phases (IUPAC Recommendations 1994)) on page 539
PAC, 1984, 56, 567 (Physicochemical quantities and units in clinical chemistry with special emphasis on activities and activity coefficients (Recommendations 1983)) on page 571