1. Chemical Engineering Thermodynamics II
Dr. Perla B. Balbuena: JEB 240
Website:
(use VPN from home)
CHEN 354-Fall 14
TA: Julius Woojoo Choi,

2. TAs office hours Julius Woojoo Choi, drspchoi@gmail.com
Office hours: Thursdays, 4-5pm, Office 613

3. TEAMS Please group in teams of 4-5 students each
Designate a team coordinator
Team coordinator: Please send an
to stating the names of all the students in your team (including yourself) no later than next Monday
First HW is due January 28.

4. Introduction to phase equilibrium
Chapter 10 (but also revision from Chapter 6)

5. Equilibrium Absence of change Absence of a driving force for change
Example of driving forces
Imbalance of mechanical forces => work (energy transfer)
Temperature differences => heat transfer
Differences in chemical potential => mass transfer

6. Energies Internal energy, U Enthalpy H = U + PV
Gibbs free energy G = H – TS
Helmholtz free energy A = U - TS

7. Phase Diagram Pure Componentf e d c b a
What happens from (a) to (f) as volume is compressed at constant T.

8. P-T for pure component

9. P-V diagrams pure component

10. Equilibrium condition for coexistence of two phases (pure component)
Review Section 6.4
At a phase transition, molar or specific values of extensive thermodynamic properties change abruptly.
The exception is the molar Gibbs free energy, G, that for a pure species does not change at a phase transition

11. n = constant => ndG =0 => dG =0
Equilibrium condition for coexistence of two phases (pure component, closed system)
d(nG) = (nV) dP –(nS) dT
Pure liquid in equilibrium with its vapor, if a differential amount of liquid evaporates at constant T and P, then
d(nG) = 0
n = constant => ndG =0 => dG =0
Gl = Gv
Equality of the molar or specific Gibbs free energies (chemical potentials) of each phase

12. Chemical potential in a mixture:
Single-phase, open system:
mi :Chemical potential of component i in the mixture

13. Phase equilibrium: 2-phases and n components
Two phases, a and b and n components:
Equilibrium conditions:
mia = mib (for i = 1, 2, 3,….n)
Ta = Tb
Pa = Pb

14. A liquid at temperature T
A liquid at temperature T in a closed container
The more energetic particles escape
Vapor pressure

15. Fugacity of 1 = f1
Fugacity of 2 = f2

16. For a pure component ma = mb
For a pure component, fugacity is a function of T and P

17. For a mixture of n components
mia = mib for all i =1, 2, 3, …n
in a mixture:
Fugacity is a function of composition,
T and P

18. Lets recall Raoult’s law for a binary
We need models for the fugacity in the vapor phase
and in the liquid phase

19. Raoult’s law

20. Raoult’s law Model the vapor phase as a mixture of ideal gases:
Model the liquid phase as an ideal solution

21. VLE according to Raoult’s law:

23. Homework # 1 download from web site Due Wednesday, 1/28