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Rosario Rajkumar, X Oxford Engineering College Trichy-620009
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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
Like dissolves like
Sugar in Water --- Dissolves
Sugar in Kerosene --- Does not dissolve
NaCl in Water
Ion-Dipole Interactions
Liquid water
O H
H
O
H
H
O
H
H
O
H
H
O
HH
OH H
Water molecules in vapour
Dipole-Dipole Interactions(Keesom Forces)
Edip-dip = 2mA2mB
2/3RAB2kT
Alcohol and water
London Forces
Polarized molecule
Neighbouringmolecue
BenzeneIodine
EABdisp = [3aAaBIAIB/2(IA+IB)] /
(1/R6)
Hydrogen Bonding
H F H F H F
Parameters
Excess volume of mixing, Heat of mixing
Internal Pressure usingDensity and viscosity
Adiabatic compressibility
Ks =1 / (U2 x d )
Gibbs Free Energy of Mixing using vapour pressures of liquids andLiquid mixtures
Force ModelEnergy, KJmol-1
Example
Ionic 400-4000 NaCl
Covalent 150-1100 H-H
Metallic 75-1000 Au
+
+
-
-
+ electrons +
+ + + +
+
+
+ + +
+ + +
e e e
e e e
Force ModelEnergy, kJmol-1 Example
Ion-dipole 40-600Na+ & H2O
Dipole-dipole 5-25
HCl and HCl
H-bond O-H ------F-H 10-40 H2O & HF
London dispersion 0.05-40
Xenon & Xenon
+ d- d+
d- d+ d- d+
d- d+ d- d+
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
Thermodynamics of SolutionsProperties 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 ixi = 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
Consider a binary solution containing liquid A and liquid B:
Interaction between A & A (like moleules)
--- A-AInteraction between B & B (like moleules)
--- B-BInteraction between A & B (unlike moleules)
--- A-BIn 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
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)
Excess volume of mixing Ethanol + Water
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 BXB = Mole fraction of liquid BMA and MB = respective molar masses of A and BdA = density of AdB = density of BdAB = density of the liquid mixture
PYKNOMETER
R D BOTTLE
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
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
ULTRSONIC INTERFEROMETER
Dewar Flask
• Dewar Flask
Q = m s T + w T
H = Heat of solution
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)
Thermodynamic parameters
• I. Prigogine 1977 Nobel Prize winner
• Best low priced Calorimeter ? Dewar flask * Most accurate thermometer to readthe difference in temperatures
? Beckmann thermo-meter
ISOTENISCOPE
Repulsive Inter-Human Interactions
• Anger• Hatred • Jealousy• Back-biting• Disobedience• EGO (Evading God-Out)• Arrogance• Greediness
Attractive Inter-Human Interactions
• Affection• Friendship• Sharing• Helping • Kindness• Respectfulness • Obedience • Gratitude
?
கற்க கசடற கற்பவை கற்றபன் நி�ற்க அதற்கு தக
Thank You