Question

Why is chemical potential is applied to only one substance at that?

Answer 1

This module is registered in the "advanced" part, despite the fact that the chemical potential belongs to basic thermodynamics. The reason is that people with a mostly physical background(like me) may often have learned exciting things like Bose-Einstein condensations and the Liouville theorem in their thermodynamics courses, but not overly much about chemical potentials and chemical equilibrium.First we will address, somewhat whimsically, a certain problem related to the name "Chemical potential". It is, in the view of many (including professors and students), a slightly unfortunate name for the quantity ∂G/∂ni; meaning the partial derivative of the free enthalpy with respect to the particle sort i and all other variables kept constant (See a pure thermodynamic script as well).