1. Chemical Engineering Thermodynamics II
Dr. Perla B. Balbuena: 240 JEB
Web site: Thermo II-Fall 10/CHEN 354-Thermo II-Fall 10.htm
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CoursesCHEN 354-Spring 10
TA: Diego Ortiz JEB 401

2. TA office hours Thursdays 3 to 5 pm
Or by appointment, please Diego to
Office: 401 JEB

3. TEAMS Please group in teams of 4-5 students each
Designate a team coordinator
Team coordinator: Please send me an stating the names of all the students in your team (including yourself) no later than this coming Friday
First HW is due Thursday, September 9.

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
Describe process 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. Now we are going to do a class exercise

12. 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

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

14. 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

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

16. 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

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

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

19. VLE according to Raoult’s law:

20. Homework # 1 Read MathCad Basics (download pdf files from web site)
Work Example 10.3 (page 359) using MathCad.
Present and explain your Mathcad solution in your HW solution
In part (a) make a graph of P-x1-y1
In part (c) make a graph of T-x1-y1
Due Thursday, September 9th