There are some articles I came across which made the distinction between chemical potential and the free energy (Gibbs energy) of the system which do get confused and I'm guilty of that.
It is why I asked if the Twank had done free energy calculations because the difference in energy (either absorbed or released) when a reaction takes place is a chemical potential calculation effectively.
In the case of salt in water, in a given volume, the addition of salt which splits into two ions, effectively dilutes the solvent and decreases the chemical potential - the values can be plugged into the right equations to show the effect that has in reducing freezing point etc.
Gibbs Free Energy and Pressure, Chemical Potential, Fugacity
Gibbs free energy per mole of substance ... This quantity is called the chemical potential and it is given the symbol, μ
Chemical potentials
In an aqueous solution of salt or of another solute, the chemical potential of water is lower than the chemical potential of pure water. The chemical potentials of pure ice and pure water vapor however, are independent of the composition of the solution from which it was formed. At equilibrium water will be in the state that has the lowest chemical potential. Therefore an aqueous solution has a lower freezing point and a higher boiling point (lower vapor pressure) than pure water.
But in terms of trying to find an explanation that can help to visualise how that happens I always look at how the molecules interact because it helps me to find some logic to help the concepts stick. Ad astra per aspera
The Gibbs Free Energy does not incorporate quantities of matter or chemical potential. Gibbs realised that when the quantity of matter can change, you need an additional energy term proportional to the quantity of matter and you define chemical potential as, (for instance) the Gibbs Free Energy per mole of substance at constant temperature and pressure. Of course, adding matter to a system at constant temperature and pressure requires increasing the volume of the system, but that's okay... En un viejo país ineficiente, algo así como España entre dos guerras civiles, poseer una casa y poca hacienda y memoria ninguna. -- Gil de Biedma
