Final answer:
The Gibbs free energy partial molar volume is represented by the derivative of Gibbs free energy with respect to the number of moles (c) ∂G/∂n) which is important for understanding the behaviour of mixtures and accounting for real gas behaviour.
Step-by-step explanation:
The Gibbs free energy partial molar volume is given by c) ∂G/∂n (the derivative of the Gibbs free energy with respect to the number of moles at constant temperature and pressure). This quantity represents how the Gibbs free energy of a system changes as the amount (in moles) of a specific component is varied, while keeping the temperature and pressure constant. It can be thought of as the contribution to the overall Gibbs free energy from an infinitesimal amount of a component added to the system. When discussing systems composed of different components, such as gases the Gibbs free energy partial molar volume is critical in understanding the behaviour of mixtures.
Contributions from interactions like those described by the van der Waals equation, which accounts for the actual volume occupied by gas molecules and the intermolecular attractions are important for real gases deviating from ideal behaviour.