lecture 1 introduction to thermodynamics

8/3/2019 Lecture 1 Introduction to Thermodynamics

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CY1001BASIC CONCEPTS

T. Pradeep

22574208

[email protected]

9/6/20101

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.html


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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

lecture 1 introduction to thermodynamics

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