Explanation :
As we know that the Gibbs free energy is not only function of temperature and pressure but also amount of each substance in the system.
[tex]G=G(T,P,n_1,n_2)[/tex]
where,
[tex]n_1\text{ and }n_2[/tex] is the amount of component 1 and 2 in the system.
Partial molar Gibbs free energy : The partial derivative of Gibbs free energy with respect to amount of component (i) of a mixture when other variable [tex](T,P,n_j)[/tex] are kept constant are known as partial molar Gibbs free energy of [tex]i^{th}[/tex] component.
For a substance in a mixture, the chemical potential [tex](\mu)[/tex] is defined as the partial molar Gibbs free energy.
The expression will be:
[tex]\bar{G_i}=\mu_i=\frac{\partial G}{\partial n_i}_{(T,P,n_j)}[/tex]
where,
T = temperature
P = pressure
[tex]n_i\text{ and }n_j[/tex] is the amount of component 'i' and 'j' in the system.
