Question

State the definition of the partial molar Gibbs energy.

Answer 1

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.

$G=G(T,P,n_1,n_2)$

where,

$n_1\text{ and }n_2$ 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 $(T,P,n_j)$ are kept constant are known as partial molar Gibbs free energy of $i^{th}$ component.

For a substance in a mixture, the chemical potential $(\mu)$ is defined as the partial molar Gibbs free energy.

The expression will be:

$\bar{G_i}=\mu_i=\frac{\partial G}{\partial n_i}_{(T,P,n_j)}$

where,

T = temperature

P = pressure

$n_i\text{ and }n_j$ is the amount of component 'i' and 'j' in the system.