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CY1001BASIC CONCEPTS
T. Pradeep
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Lecture 1
Atomists and ionists
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1. Chemical thermodynamics
2. Statistical thermodynamics
3. Kinetics
4. Surface science
Books:
1. G. W. Castellan, Physical Chemistry, 3rd Edition, Narosa, New Delhi,1995.
2. P. W. Atkins, Physical Chemistry, 8th Edition, Oxford University
Press, Oxford, 1998.
3. Silbey, Alberty, Bawendi, Physical Chemistry, 4th Ed.
Lecture schedule
Tutorials
Evaluation
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Property
Variable Time
Quantum mechanics
Statistical mechanics
Thermodynamics
Variation of heat with process
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UNIVERSE
4
SYSTEM SURROUNDING
OPEN CLOSED ISOLATED
Pressure, Volume, Temperature, Heat,
Mass
Intensive and ExtensiveVariables
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What is unique about Thermodynamics?
Independent of atomic and molecular theory.
In chemical systems, thermodynamics helps to keep a record of energy flow.
Equilibrium state of a chemical system can be understood from
thermodynamics.
It is a logical science, three statements describe thermodynamics; deductionsfrom these laws constitute the equations.
Validity of thermodynamic laws depends only on the basic laws and the logical
deductions which follow from them.
Since thermodynamics is itself a science, not dependent upon the foundations ofother branches, it has an existence of its own.
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System
Surroundings
Characterization of a systemBased on properties
(1) intensive properties and (2) extensive properties
Types of systems(1) open, (2) closed, and (3) isolated systems.
(1) homogeneous or (2) heterogeneous
Chemical systemPhase, Component
Process, PathState function, Path function
Exact and inexact differentials
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Zeroth LawA B and B C, then A C { = thermal
equilibrium}
First Law
Law of conservation of energy
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q and w are positive, when energy is transferred to the system
q and w are negative, when energy is lost from the system
Exact and Inexact differentials
=b
a
ab wwww )(
Exact differential
Inexactdifferential
UUUdU
b
a
ab ==
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Sum of two inexact differentials can be
an exact differential (first law)
Test for exactness-Euler's theorem
),( yxfz = dyy
zdx
x
zdz
xy
+
=if then,
When
yxxy y
z
xx
z
y
=
Then z is an
exact differential
Inexact differentials can be converted to exact differentials bymultiplying with integrating factors
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The General Expression for Work
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From Physics, Work, w = Fd cos
When = 1800, Work, w = -Fd
dw = -F.dz
But, F = Pressure x Area = P.A
Therefore, dw = -P.A.dz
Now, A.dz = dV
dw = -P.dV
F
w
=2
1
V
V
PdVw
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Concept of reversibility
P1, V1, T
m
mh P1
P2
V2 V1P1, V1 P2, V2
SINGLE STEP COMPRESSION
)( 122 VVPmghw ==
Two, three and infinite number of steps
Same compression can beDone with less work ! ==
2
1
V
V
PdVww
A
mgP =2
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Different situations
Free expansion
Expansion against constant pressure
If P is constant,
Isothermal reversible expansion
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Fw
w = - P (V2 V1)
=2
1
V
VV
dVnRTw
1
2lnV
VnRTw =
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dV
V
UdT
T
UdU
TV
+
=
HEAT CAPACITY
U as a function of T and V
dVVUPdT
TUq
T
ext
V
++
=
dVPqdU ext=Since,
At constant volume, dT
Uq
V
V
=
V
V
V CT
U
dT
q=
=
Heat capacity at constant volume
CdT
q=
Path dependant(constant V or T)
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HEAT CAPACITY
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=2
1
T
T
VV dTCU
V
VT
UC
=
If CV is constant over a small range of temperature, TCU VV =
gas vacuum
We have seen that,dV
V
UdT
T
UdU
TV
+
=
0=
= dV
V
UdU
T Since Joule Found that
q = 0;and w =00=
TV
USince dV0,
This is not correct for real gases.
Internal Pressure
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H = U + PV
Change of state at constant pressure
Enthalpy
)12(12
VVPqpVPqUUU P ===
( ) ( )1122 PVUPVUqP ++=
12HHqP =
dHqP =
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Enthalpy, H = U + PVCalorimetry
Isotherm and adiabat
ThermochemistryHeat of formation, fH
o
Hesss Law
Born-Haber Cycle
Kirchhoffs equation
rHo (T2) = rH
o (T1) + rCpoEquipartition principle
AdIsothermP 1/VAdiabat
P 1/V
P
V
dT
Joule experiment T = (U/V)TJoule-Thomson Experiment
= (T/P)H
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Galileo Galilei 1564-1642
It is all about heat. Thermodyn
amics,H
istory
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Joseph Black, 1728 - 1799Francis Bacon 1561-1626
http://www.fbrt.org.uk/pages/bacon/ptii/frameset-ptii.htmlhttp://www.fbrt.org.uk/pages/bacon/pti/frameset-pti.htmlhttp://www.fbrt.org.uk/pages/bacon/bacon-ptvii.htmlhttp://www.fbrt.org.uk/pages/bacon/bacon-george.htmlhttp://www.fbrt.org.uk/pages/bacon/bacon-gt.instrauration.htmlhttp://www.fbrt.org.uk/pages/bacon/bacon-alban.htmlhttp://www.fbrt.org.uk/pages/shakespeare/frameset-shakespeare.htmlhttp://www.fbrt.org.uk/pages/bacon/ptiii/frameset-ptiii.htmlhttp://www.fbrt.org.uk/pages/bacon/bacon-plato.html8/3/2019 Lecture 1 Introduction to Thermodynamics
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James Prescott Joule 1818-1889
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James Watt 1736 - 1819
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Sadi Carnot 1796-1832
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Rudolf Clausius 1822 - 1888
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Lord Kelvin (William Thomson) 1824-1907
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Ludwig Boltzmann 1844-1906
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Josiah Willard Gibbs 1839-1903
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Jacobus Henricus van 't Hoff 1852-1911
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Walther Hermann Nernst 1864 - 1941
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Gilbert Newton Lewis 1875-1946