activity coefficient, f, γ

https://doi.org/10.1351/goldbook.A00116
The activity coefficient fB of a substance B in a liquid or solid mixture containing mole fractions xB, xC, ... of the substances B, C, ... is a dimensionless quantity defined in terms of the chemical potential μB of B in the mixture by: R T ln⁡(xB fB)=μB(cd,T,P,x)−μB∗(cd,T,p) where x denotes the set of mole fractions xB, xC, ... . The activity coefficient γB of a solute B in a solution (especially a dilute liquid solution) containing molalities mB, mC, ... of solutes B, C, ... in a solvent A is a dimensionless quantity defined in terms of the chemical potential μB by: R T ln⁡(mB γBm⊖)=μB−{μB−R T ln⁡(mBm⊖)}∞
Sources:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2171 [Terms] [Paper]
PAC, 1994, 66, 533. (Standard quantities in chemical thermodynamics. Fugacities, activities and equilibrium constants for pure and mixed phases (IUPAC Recommendations 1994)) on page 543 [Terms] [Paper]
PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 960 [Terms] [Paper]
Citation: 'activity coefficient' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.A00116 RIS BibTex EndNote
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Last revised: February 24, 2014