fugacity coefficient, ϕ

https://doi.org/10.1351/goldbook.F02544
Ratio of fugacity to the partial pressure of a gaseous constituent.
Sources:
Green Book, 2nd ed., p. 50 [Terms] [Book]
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 [Terms] [Paper]