[noor123]

Can someone please define and describe the applications of the chemical potential of a substance?

I know the definition which is that the chemical potential of a substance is the partial molar Gibbs energy of that substance in a mixture.
But not sure about the applications...

[Plontaj]

Standard change free Gibbs energy of reaction determine constant of reaction K and therefore direction of reaction.
K=exp(-Δ^oGr/RT)

ΔGr=Δ^oGr+zi*RT*ln(pi) eg. in gas-phase reaction
ΔGr=0 - equilibrium
ΔGr>0 - reaction is thermodynamically limited
ΔGr<0 - reaction can go (in right) if there aren't any others limits (like kinetic or diffusion)