fugacity, Math - title, Math - title

https://dx.doi.org/10.1351/goldbook.F02543
Of a substance B, Math - text or Math - text, in a gaseous mixture is defined by Math - ei, where Math - text is the partial pressure of B and Math - text its absolute activity.
Source:
See also:
PAC, 1994, 66, 539 (Standard quantities in chemical thermodynamics.)
PAC, 1984, 56, 571 (Physicochemical quantities and units in clinical chemistry with special emphasis on activities and activity coefficients.)