Of substance B at temperature \(T\), \(\mu _{\rm{B}}^{\rm{o}}(T)\), is the value of the chemical potential under specified standard conditions (in the standard state).
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 536 [Terms] [Paper]