1. About determination of partial molar volumenB
Measurement
M(CuSO4)/g
ρ/g.cm
V/cm
Method 1
Method 2 α
W2% α1 α2

2. Measurement of saturated vapour pressure
External pressure
Pressure

3. 5.4.2 Phase diagrams of partly miscible binary systems
Extraction technique
Φmin=1, Fmax=3
( )p, T,X
313K
363K
373K
critical consolute temperature
( the upper…)
Φ=2, F= ()T

4. Example
Mixture of 50g of hexane (0.59mol) and 50g of nitrobenzene (0.41mol), 290K.
Questions: (1) the compositions of the phases;
(2) To what temperature the sample be heated in order to obtain a single phase?
T=290K, horizontal tie line
xhexane=0.35; lα
xnitrobenzene=0.83; lβ
Tc=292K

5. Why two phases coexisting : the thermodynamic basic principle
ΔmixG = nRT(xA ln xA + xB ln xB + βxAxB)
GE = nβRTxAxB
The location of the phase boundary on the basis of the βparameter
Interpretation about the lever rule

6. H2O-triethylamine (C2H5)3N
291.2K
The lower critical solution temperature

7. H2O-nicotinamide
481K
334 K
Upper and lower critical consolute temperatures

8. H2O-ethyl ether
No critical consolute temperature

9. Inferring according to the phase diagram
Higher temperature range
Phase state variation following path a1-a2:
L - L+G - G
Low-boiling azeotrope
Phase state variation following path b2-b1:
L1+L2 – L - L+G -G
Partly miscible in liquid solution
Partly miscible in liquid solution
How about b1-b2 ?

10. T-x phase diagram for a binary system
Phase state variation following path a1—a2:
e1-e2
b1-b2:
F=2-1+1=2
F=2-2+1=1
F=2-3+1=0
F=2-1+1=2
F=2-2+1=1
Boiling occurs before the two liquids are fully miscible

11. Example
State the changes that occur when a mixture of composition xB=0.95
0.62:1
0.82:1

12. 5.4.3 Immiscible systems L1 L2 G
incapable of mixing

13. F=2-3+1=0 T=90℃ P=9.79X104Pa A(l)+B(l) b a g T P g+B(l) g+B(l) g
A(l)+g
g+B(l)
g+B(l)
A(l)+g g
A(l)+B(l)
H2O
C6H5Cl
H2O
C6H5Cl

14. Water vapour distillation

15. 5.4.4 Phase diagrams of Liquid-solid binary systems
a1-a5: b
F=2-3+1=0
Path b:
EutecticsxB

16. Water-salt system

17. Application Consolute temperature Water-salt 252 K 218 K 262.5 K

18. Homework Y: P166 22; P169:25 A: P216 8.13(a) 8.17(a) P218 8.2 Preview: