1. Classical Thermodynamics of Multicomponent Systems
Lecture 16
Classical Thermodynamics of Multicomponent Systems
Activity
Partial molar quantities
Calculations of partial molars from total quantities
Problems

2. Activity Defining Upon integration
Where is arbitrary and typically taken as of a pure component at a temperature of interest

3. Ideal gas activity Chemical potential of an ideal gas
Where Pi is the partial pressure of ith component
Where is arbitrary and typically taken as the pressure over the pure condensed phase o the species i. With this choice

4. Partial Molar Properties
Total Gibbs free energy
On the molar bases
Where is the partial molar Gibbs free energy

5. Partial Molar Properties II
From and
Where the derivative is with respect to number of moles, not atoms or molecules
Similarly for volume

6. Partial Molar Properties III
Other relations
And similar

7. Calculating partial properties from total
For a two component system
Since
With and

8. Problem 18.5
The molar Gibbs free energy of a binary system at a particular temperature and pressure is given by
Calculate the partial molar Gibbs free energies for A and B at a composition of XB = 0.3