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CYL110
• CYL110 - Physical Chemistry: Concepts and
Applications [4 cr. (3-1-0)]
• Semester I 2012-13, M, Th (9:30- 11), Tue-Thurs 2:003:00 (MS418)
• Instructors: Dr. Shashank Deep (SD) and Dr. Pramit K
Chowdhury(PKC)
• Course Coordinator: Prof. Siddharth Pandey (PKC)
• Office: MS731 (SD)
• Phone: 6596 (SD)
• E-mail: [email protected] (SD)
CYL 110 Grading
• Grading based on:
•
•
•
•
•
Minor Tests I
Minor Tests II
2 Quizzes
Major Test
Passing grade is 30%.
20%
20%
20%
40%
Recommended books
• Books and Reference Material:
• (i) Physical Chemistry by Atkins and de Paula
• (ii) The Elements of Physical Chemistry by Atkins
• (iii) Physical Chemistry by Silbey and Alberty
• (iv) Physical Chemistry by Levine
• (vi) Physical Chemistry: A Molecular Approach by
McQuarrie and Simon
• (vii) Physical Chemistry by Laidler, Meiser, and Sanctuary
Course contents
(chemical Thermodynamics)
• Zeroth law of themodynamics, Ideal and real
gases, van der Waals and virial equations of state,
Critical point.
• First law of thermodynamics and internal energy,
Exact and inexact differentials, Isothermal and
adiabatic processes, Enthalpy, Joule-Thompson
expansion, Heat Capacities.
• Second law of thermodynamics and entropy,
entropy changes in reversible and irreversible
processes.
Course contents
(Chemical Thermodynamics)
• Combined first and second law, thermodynamic
potentials, free energy and work, effect of temperature
and pressure on free energy.
• Chemical potential, equilibrium and free energy, phase
equilibria: phase rule, phase equilibrium of onecomponent system, clapeyron equation, clausius
clapeyron equation, colligative properties.
• Gaseous equilibrium, Le Chatelier’s principle, van’t Hoff
equation.
CYL110 Tutorials
• http://web.iitd.ac.in/~sdeep
• Menu
• Tutorial I-V
Courses
CYL110
Thermodynamics
• Effects of gravitational field, centrifugal field and surface
area on the properties of the system.
• Phase transitions like graphite to diamond conversion,
helium normal to superfluid transition, conductor to
semiconductor transition, change of boiling point of a
liquid with pressure or addition of solute.
• Biochemistry-Enzymes and protein stability, DNA
stability, metabolic processes leading to mechanical
work performed by a living organism, design of drugs.
Thermo---------• Industrial Chemistry-Different chemical
processes like synthesis of ammonia from
nitrogen and hydrogen.
• Thermodynamics of complexation with
macrocyclic ligands- A system of interest in
Inorganic chemistry and chemical separation.
• Geological problems- solubility of calcite,
energetics of ternary oxides of minerological
significance.
A thermodynamic system is that portion of the
Universe that we have selected for investigation
•The surroundings are everything outside
the system.
The boundary separates the system from
the surroundings
The state of a system is defined as the complete set
of all its properties which can change during
various specified processes.
When a system is at equilibrium, its state is defined
entirely by the state variables, and not by the
history of the system.
The properties of the system can be described by an
equation of state which specifies the relationship
between these variables.
System--------------------------
GAS
Variables---------------------- n, P,V,T
Equation of State -------- PV=nRT
A perfect gas is defined as “A gas where intermolecular forces are negligible”.
Temperature
• Zeroth law of thermodynamics.
• Do we need definition of temperature ?
• On a cold winters day a metal railing feels
much colder than a wooden fence post,
but they are both at the same temperature.
• The zeroth law states “If two systems are
separately in thermal equilibrium with a
third, then they must also be in thermal
equilibrium with each other.”
Bulk Variables
• V, the Volume the
sample occupies (m3)
m3 = 106 cc = 1000 L
• p, the Pressure of the
sample (atm)
1 atm = 101.325 kPa =
1.01 bar = 760 Torr
• T, the Temperature of
the sample
(K)
• n, Composition - moles
Ideal Gas Model
• Molecules may be treated as point masses
relative to the volume of the system.
• Molecular collisions are elastic, i.e. kinetic
energy is conserved.
• Intermolecular forces of attraction and
repulsion have negligible effect on the
molecular motion.
Compressibility
• The compressibility of a gas is defined by
pVm
Z
RT
• If the gas behaves ideally, then Z=1 at all pressures and
temperatures.
• Z >1 molecules occupy more volume than IG (e.g. H2):
repulsive forces
• Z < 1 molecules occupy less volume than IG (e.g. CO2):
attractive forces
Critical constants of some gases
• The very low critical pressure and temperature of helium, reflecting
the very small intermolecular attractions of this atom. • Tc of the
noble gas elements increases with atomic number.
• Hydrogen gas cannot be liquified above 33 K; this poses a major
difficulty in the use of hydrogen as an automotive fuel; storage as a
high-pressure gas requires heavy steel containers which add greatly
to its effective weight-per-joule of energy storage.
• The properties of carbon dioxide (particularly its use as a
supercritical fluid).
• The high Tc of H2O is another manifestation of its "anomalous"
properties relating to hydrogen-bonding.
Calculation of critical point
a point on a curve at which
the tangent crosses the
curve itself.
a point on a curve at which
the curvature changes sign.
A point on a curve at which
the second derivative
changes sign.
a point (x,y) on a function,
f(x), at which the first
derivative, f'(x), is at an
extremum, i.e. a minimum or
maximum.
Super critical fluid
(Gases above their TC and Pc)
It possesses the flow properties of a gas and
the solvent properties of a liquid.
Supercritical Fluid is an example of gas
which can dissolve solids.
The density of a supercritical fluid can be
changed over a wide range by adjusting the
pressure; this, in turn, changes its solubility,
which can thus be optimized for a particular
application.
Soluble components are extracted from a substrate
by a high pressure gas, and the extracted
components that have been dissolved in the gas are
precipitated from the gas when the pressure is
reduced.
Major drawback in using liquids as a solvent is
the presence of residual solvents in the
product.
Super critical fluids are used for
decaffeinating coffee and tea and extracting
flavors, aroma and essential oils from hops,
spices, flowers and herbs.
Virial equation of state
It is based on statistical mechanical theory,
where each power level indicates a higher level
of interaction.
The virial equation does not tend to be very
good at high densities (low T, high P).
Boyle’s temperature
 Z 

 0
 P T




 Z 
  0
  1  
 V  
  m 
B0
as
P0
as
V 
van der Waals Equation
 p  a / V V
2
m
m
 b  nRT
Vm,eff  Vm  b
repulsion
peff  p  a / V
attraction
2
m
van der Waals constants
a (dm6 atm mole-1) b (dm mole-1)
He
0.034
0.0237
Ar
1.345
0.0322
N2
1.390
0.0391
O2
1.360
0.0318
CO2
3.592
0.0427