Excess Thermodynamic Properties . Excess volume of mixing, Heat of mixing, deviation in adiabatic compressiblitgies of liquid mixtures (homogeneous and non-reacting)

1. Excess Thermodynamic Properties
X. Rosario Rajkumar
Department of Humanities and Science
Oxford Engineering College
Tiruchirappalli – 620 009
at
Cauvery College for Women, Tiruchirappalli
December 16, 2011 (Friday)
Innovation is our strength

2. Like dissolves like
Sugar in Water --- Dissolves
Sugar in Kerosene ---
Does not dissolve

3. NaCl in Water

5. Ion-Dipole Interactions

6. O
H H H
O
H
O H
H
Water molecules in vapour
H H
O H O
H
H O
H
Liquid water

7. Dipole-Dipole Interactions
(Keesom Forces)
Alcohol and water
Edip-dip = 2mA2mB2/3RAB2kT

8. London Forces
Polarized Neighbouring
molecule molecue
Benzene
Iodine
EABdisp = [3aAaBIAIB/2(IA+IB)] / (1/R6)

9. Hydrogen Bonding
H F H F H F

10. Parameters
Excess volume of Internal Pressure
mixing, Heat of using
mixing Density and
viscosity
Adiabatic Gibbs Free Energy
compressibility of Mixing using
vapour pressures of
Ks =1 / (U2 x d ) liquids and
Liquid mixtures

11. Energy,
Force Model Example
KJmol-1
+ -
Ionic 400-4000 NaCl
- +
Covalent + electrons + 150-1100 H-H
+ + + +
e e e
Metallic + + + + 75-1000 Au
e e e
+ + + +

12. Energy,
Force Model Example
kJmol-1
Ion-dipole + d- d+ 40-600 Na+ & H2O
Dipole-
dipole d- d+ d- d+ 5-25 HCl and HCl
H-bond O-H ------F-H 10-40 H2O & HF
London d- d+ d- d+ Xenon &
dispersion 0.05-40
Xenon

13. Ideal gas?
• No intermolecular interaction
• Obeys ideal gas equation, PV = nRT
• At low P and at high T, a real gas tends to
to ideal gas

14. Thermodynamics of Solutions
Properties of Ideal Solutions:
1. There is no volume change when an ideal
solution is formed from its pure components
2. There is no evolution or absorption of heat
during the formation of an ideal solution
3. An ideal solution obeys Raoult’s law
pi = xi pio
pi = partial vapour pressure of i
xi = mole fraction of I in the solution
pio = vapour pressure of pure component i
4. In an ideal solution the intermolecular
interactions between like molecules is equal
to that of unlike molecules

15. Consider a binary solution containing liquid A
and liquid B:
Interaction between A & A (like moleules)
--- A-A
Interaction between B & B (like moleules)
--- B-B
Interaction between A & B (unlike moleules)
--- A-B
In an ideal solution,
A-A or B-B = A-B
In a non-ideal solution,
A-A or B-B not equal to A-B

16. 100mL of alcohol + 100mL of water = ----- mL of solution
Why?
•Rupture of H-bonds in alcohol by the addition
of water
• Breaking up of H-bonds in water by the
addition of alcohol
• Formation of H-bonds between alcohol and
water
• Dipole-dipole interactions
VE = (volume after mixing) – (volume before mixing)

17. Excess volume of mixing Ethanol + Water

18. VE ={ [XA MA + XB MB ] / dAB}- [ XA MA / dA] + [ XB M B / dB ]
VE = Excess Volume of Mixing of two liquids A and B (non-
reacting, homogeneous)
XA = Mole fraction of liquid A in the solution of A and B
XB = Mole fraction of liquid B
MA and MB = respective molar masses of A and B
dA = density of A
dB = density of B
dAB = density of the liquid mixture

19. PYKNOMETER

20. R D BOTTLE

21. Experimental Methods
 Measurement of Density of liquid and
Liquid mixtures using Pyknometer or
RD Bottle or Densimeter.
 Measurement of Heat of Mixing by
Calorimetry.
 Measurement of ultrasonic velocity in
liquids and liquid mixtures by interferometry.
 Vapour pressure by Isoteniscope

22. Deviation in isentropic
copressibility (Ks)
• Ks = Ks,mix – ( x1Ks1 + x2Ks2)
• Ks,mix = isentrpic compressiblity of the liquid
• mixture
• Ks1 and Ks2 are respective isentropic
comressibilities of liquid 1 and 2
• X1 and X2 are respective mole fractions

23. ULTRSONIC INTERFEROMETER

24. • Dewar Flask
Dewar Flask

25. Q = m s T + w T
H = Heat of solution

26. Density of liquids/liquid mixtures
• Density = (m/m0)xdo at T
• m = mass of certain volume of liquid
• m0 = mass of same volume of water
• d0 = density of water at T (from Tables)

27. Thermodynamic parameters
• I. Prigogine 1977 Nobel • Best low priced
Prize winner Calorimeter ?
Dewar flask
* Most accurate
thermometer to read
the difference in temperatures
?
Beckmann thermo-
meter

28. ISOTENISCOPE

29. Repulsive Inter-Human Interactions
• Anger
• Hatred
• Jealousy
• Back-biting
• Disobedience
• EGO (Evading God-Out)
• Arrogance
• Greediness

30. Attractive Inter-Human Interactions
• Affection
• Friendship
• Sharing
• Helping
• Kindness
• Respectfulness
• Obedience
• Gratitude

31. ?