1. Physical Chemistry I (TKK-2246)
14/15 Semester 2
Physical Chemistry I (TKK-2246)
Instructor: Rama Oktavian
Office Hr.: M – F.13-15

2. Outlines 1. Review 2. Liquid-liquid equilibria (2-components)
4. Ternary diagrams

3. Review

4. Review Ch. 12 Equilibrium condition
the chemical potential of each substance must have the same value in every phase in which that substance appears
a state in which there are no observable changes as time goes by.

5. Review
Ch. 12
Phase diagram

6. Review Ch. 12 Phase rule the phase rule for a one-component system
Gibbs Phase Rule

7. Review
Ch. 13
Solution
Solution - homogeneous mixture of chemical species
One phase

8. Review
Ch. 13
Raoult’s Law and Ideal Solution (only one volatile componet)
Raoult’s law

9. Review
Ch. 14
Raoult’s Law and Binary Ideal Solution

10. Review
Ch. 14
Gaseous phase
Partial pressure of component 1

11. Review
Ch. 14

12. Review
Ch. 14
P-x,y diagram

13. Review
Ch. 14
T-x,y diagram

14. Review
Ch. 14
Azeotropes

15. Review
Ch. 14

16. Liquid-liquid equilibria
Basic concept of miscibility
Miscible – e.g: Toluene-benzene
Partially miscible – e.g: water-phenol
Immiscible – e.g: water-nitrobenzene

17. Liquid-liquid equilibria
Basic concept
Partially miscible solution
In equilibrium condition
Liquid (upper layer)
A + B
Liquid (bottom layer)
A + B

18. Liquid-liquid equilibria
Partially miscible liquid
P= 2, F= 1 the selection of temperature makes the compositions of the immiscible phases fixed
P= 1, F = 2 (two liquids are fully mixed) both temperature and composition can be changed

19. Liquid-liquid equilibria
Partially miscible liquid
1. Add small amount of nitrobenzene to hexane at 290 K, it still dissolves completely, P = 1
2. Add more nitrobenzene to hexane and mixture of nitrobenzene-hexane becomes saturated, add more nitrobenzene, the mixture will become two phases (line 2-3).
3. In point 3, the mixture will become saturated (more nitrobenzene)
4. In point 4, the mixture will become one phase (hexane will dissolve in nitrobenzene)

20. Liquid-liquid equilibria
Representation of liquid liquid phase diagram
Point A - Mixture of 50 g hexane (0.59 mol C6H14) and 50 g nitrobenzene (0.41 mol C6H5NO2) was prepared at 290 K A
There will be two phases solution with the composition at point 2 and point 3
xN= 0.35 and xN= 0.83 (these are
the compositions of the two phases

21. Liquid-liquid equilibria
Representation of liquid liquid phase diagram
Use Lever-Rule to determine the ratio of amount of each phase: A
There is 7 times as much hexane-rich phase as there nitrobenzene-rich phase
If the mixture is heated to 292 K, we go into a single phase region

22. Liquid-liquid equilibria
Representation of liquid liquid phase diagram

23. Liquid-liquid equilibria
Critical solution temperature
1. The upper critical solution temperature, Tuc
2. The lower critical solution temperature, Tlc

24. Liquid-liquid equilibria
Critical solution temperature
1. The upper critical solution temperature, Tuc
The upper critical solution temperature, Tuc, is the highest temperature at which phase separation occur

25. Liquid-liquid equilibria
Critical solution temperature
2. The lower critical solution temperature, Tuc
The lower critical solution temperature, Tlc, is the lowest temperature at which phase separation occur
For triethylamine and water, the system is partially miscible above Tlc, and single phase below

26. Liquid-liquid equilibria
Critical solution temperature
Some systems have both Tuc and Tlc, with a famous example being nicotine in water, where Tuc= 210oC and Tlc= 61oC

27. Liquid-liquid equilibria1
Xnicotine
Temperature ( oC ) X2 X1 X3 T1
210 oC
61 oC T2 T3
nicotine / water solution
nicotine saturated water rich phase in equilibrium with a water saturated nicotine rich phase T4
lower consulate temperature
we cool a nicotine water solution of composition X2 from some temperature above the upper consulate temperature of 210 oC.
At temperatures greater than T1 the nicotine and water are miscible
When T1 is reached water saturated nicotine rich phase just begins to form and is in equilibrium with the predominant nicotine saturated water rich phase
As the system is further cooled there will be two phase region. In the two phase region the relative amounts of the phases present are again given by the lever law, e.g. at T2 we have:
nX1 (X2 - X1) = nX3 (X3 - X2)

28. Liquid-liquid equilibria
Distillation of partially miscible liquids
First case - the Tuc is lower than the azeotrope temperature

29. Liquid-liquid equilibria
Distillation of partially miscible liquids
a1 initial composition and temperature –one phase
a2 the point where boiling begins and the vapor will have composition at b1
When the distillate is cooled enough to cause condensation, a single phase first forms, represent by point b2
point b3 represents the overall composition once the temperature is lowered back to the starting temperature

30. Liquid-liquid equilibria
Distillation of partially miscible liquids
Another case - the Tuc is higher than the azeotrope temperature

31. Liquid-liquid equilibria
Distillation of partially miscible liquids
a1 initial composition and temperature –one phase
It will start boiling at point a2 with vapor having composition given by point b1
This distillate will condense into a two phase liquid directly (b3).

32. Liquid-liquid equilibria
Distillation of partially miscible liquids
A system at e1 forms two phases up to the boiling point at e2
condensing a vapor of composition e3
gives a two-phase liquid of the same overall composition
At e2, F = 0, their compositions and the temperature are fixed

33. Liquid-liquid equilibria

34. Liquid-liquid equilibria
Distillation of immiscible liquids
Immiscible liquids

35. Liquid-liquid equilibria
Distillation of immiscible liquids
Immiscible liquids
The total vapor pressures of liquids is

36. Liquid-liquid equilibria
Distillation of immiscible liquids

37. Liquid-liquid equilibria
Distillation of immiscible liquids
Example: Aniline(1)-water(2) system, we want to distill 100 g of water from this mixture at 98.4°C under atmospheric condition
The mass of aniline that distills for each 100 g of water

38. Liquid-liquid equilibria
System of three components
Call Gibbs Phase Rule
P = 1, F = 4 – T, P, x1, x2
P = 2, F = 3 – T, P, x1

39. Liquid-liquid equilibria
Ternary phase diagram
How to read it
100% C
100% B
100% A

40. Liquid-liquid equilibria
Ternary phase diagram
Ternary phase diagram for methyl isobutyl ketone + acetone + water
Binodal / cloud point curve
Liquid-liquid phase separation occurs
Plait point

41. Thank You !