CY1001 BASIC CONCES Lecture 1. radeep 22574208 pradeep@iitm.ac.in Atomists and ionists 9/6/2010 1
1. Chemical thermodynamics 2. Statistical thermodynamics 3. Kinetics 4. Surface science Books: 1. G. W. Castellan, hysical Chemistry, 3 rd Edition, Narosa, New Delhi, 1995. 2.. W. Atkins, hysical Chemistry, 8 th Edition, Oxford University ress, Oxford, 1998. 3. Silbey, Alberty, Bawendi, hysical Chemistry, 4th Ed. Lecture schedule utorials Evaluation
Quantum mechanics Statistical mechanics roperty hermodynamics ariation of heat with process ariable ime
UNIERSE SYSEM SURROUNDING OEN CLOSED ISOLAED Intensive and Extensive ariables ressure, olume, emperature, Heat, Mass 4
What is unique about hermodynamics? 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; deductions from these laws constitute the equations. alidity 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 of other branches, it has an existence of its own.
A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the more extended its area of applicability. Hence the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content concerning which I am convinced that, within the framework of the applicability of its basic concepts, it will never be overthrown. Albert Einstein
System Surroundings Characterization of a system Based on properties (1) intensive properties and (2) extensive properties ypes of systems (1) open, (2) closed, and (3) isolated systems. (1) homogeneous or (2) heterogeneous Chemical system hase, Component rocess, ath State function, ath function Exact and inexact differentials
Zeroth Law A B and B C, then A C { thermal equilibrium} First Law Law of conservation of energy
Work, heat Exothermic, endothermic First Law du dq dw Internal energy of an isolated system is constant ex d ex Work - ex d Free expansion 0 Isothermal work -(nr/) d - nr ln f / i (reversible) i f Indicator diagram James Watt
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 du U b U a U Exact differential 9/6/2010 b a w w( w b w a ) Inexact differential 10
9/6/2010 11 Sum of two inexact differentials can be an exact differential (first law) est for exactness-euler's theorem ), ( y x f z dy y z dx x z dz x y + if then, When y x x y y z x x z y hen z is an exact differential Inexact differentials can be converted to exact differentials by multiplying with integrating factors
he General Expression for Work From hysics, Work, w Fd cos θ When θ 180 0, Work, w -Fd w dw -F.dz F But, F ressure x Area.A herefore, dw -.A.dz Now, A.dz d dw -.d w 2 d 1 9/6/2010 12
Concept of reversibility 1, 1, m 2 SINGLE SE COMRESSION mg 2 A h m 1 w mgh ( 1) 2 2 1, 1 2, 2 2 1 wo, three and infinite number of steps Same compression can be Done with less work! w w 2 1 d 9/6/2010 13
Different situations F w Free expansion Expansion against constant pressure If is constant, w - ( 2 1 ) Isothermal reversible expansion 9/6/2010 w nr 2 1 d w nr ln 2 1 14
9/6/2010 15 d U d U du + HEA CAACIY U as a function of and d U d U q ext + + d q du ext Since, At constant volume, d U q C U d q Heat capacity at constant volume C d q ath dependant (constant or )
HEA CAACIY C U U 2 1 C d If C is constant over a small range of temperature, U C We have seen that, du U d + U d gas vacuum Since d 0, du U d U 0 0 Since Joule Found that q 0; and Internal ressure w 0 9/6/2010 his is not correct for real gases. 16
Change of state at constant pressure Enthalpy U U U q qp ( 2 2 1 ( U + ) ( U ) q + 2 2 1 1 1) q H 2 H 1 H U + q dh 9/6/2010 17
H as a function of and dh H d + H d Since q dh and at constant, q H d q d H C Heat capacity at constant pressure If C is independent of temperature, H C 9/6/2010 18
9/6/2010 19 C - C nr d U d U q ext + + divide by d and setting C d dq U C C + For an ideal gas, and nr 0 U nr C C
Enthalpy, H U + Calorimetry Isotherm and adiabat hermochemistry Heat of formation, Δ f H o Hess s Law Adiabat α1/ γ Isotherm Ad α1/ Born-Haber Cycle Kirchhoff s equation Δ r H o ( 2 ) Δ r H o ( 1 ) + ʃ Δ r C p o Equipartition principle d Joule experiment Π (U/ ) Joule-homson Experiment μ (/ ) H
It is all about heat. Galileo Galilei 1564-1642 hermodynamics, History
Francis Bacon 1561-1626 Joseph Black, 1728-1799
James rescott Joule 1818-1889
James Watt 1736-1819
Sadi Carnot 1796-1832
Rudolf Clausius 1822-1888
Lord Kelvin (William homson) 1824-1907
Ludwig Boltzmann 1844-1906
Josiah Willard Gibbs 1839-1903
Jacobus Henricus van 't Hoff 1852-1911
Walther Hermann Nernst 1864-1941
Gilbert Newton Lewis 1875-1946