.MCAD 304020000 1 79 954 0 .CMD PLOTFORMAT 0 0 1 1 1 0 0 1 1 0 0 1 1 1 0 0 1 1 0 1 0 0 1 1 NO-TRACE-STRING 0 2 1 0 1 1 NO-TRACE-STRING 0 3 2 0 1 1 NO-TRACE-STRING 0 4 3 0 1 1 NO-TRACE-STRING 0 1 4 0 1 1 NO-TRACE-STRING 0 2 5 0 1 1 NO-TRACE-STRING 0 3 6 0 1 1 NO-TRACE-STRING 0 4 0 0 1 1 NO-TRACE-STRING 0 1 1 0 1 1 NO-TRACE-STRING 0 2 2 0 1 1 NO-TRACE-STRING 0 3 3 0 1 1 NO-TRACE-STRING 0 4 4 0 1 1 NO-TRACE-STRING 0 1 5 0 1 1 NO-TRACE-STRING 0 2 6 0 1 1 NO-TRACE-STRING 0 3 0 0 1 1 NO-TRACE-STRING 0 4 1 0 1 1 NO-TRACE-STRING 0 1 1 21 15 0 0 3 .CMD FORMAT rd=d ct=10 im=i et=3 zt=307 pr=3 mass length time charge temperature tr=0 vm=0 .CMD SET ORIGIN 0 .CMD SET TOL 0.001000000000000 .CMD SET PRNCOLWIDTH 8 .CMD SET PRNPRECISION 4 .CMD PRINT_SETUP 1.000000 1.000000 1.200000 1.200000 0 .CMD HEADER_FOOTER 1 0 *empty* |F *empty* 0 1 Created:^Spring^1997|NModified:^August^1997 |F Author;^Sidney^H.^Young^&Theresa^Julia^Zielinski|NPage^^|P .CMD HEADER_FOOTER_FONT fontID=14 family=Arial points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD HEADER_FOOTER_FONT fontID=15 family=Arial points=9 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFAULT_TEXT_PARPROPS 0 0 0 .CMD DEFINE_FONTSTYLE_NAME fontID=0 name=Variables .CMD DEFINE_FONTSTYLE_NAME fontID=1 name=Constants .CMD DEFINE_FONTSTYLE_NAME fontID=2 name=Text .CMD DEFINE_FONTSTYLE_NAME fontID=4 name=User^1 .CMD DEFINE_FONTSTYLE_NAME fontID=5 name=User^2 .CMD DEFINE_FONTSTYLE_NAME fontID=6 name=User^3 .CMD DEFINE_FONTSTYLE_NAME fontID=7 name=User^4 .CMD DEFINE_FONTSTYLE_NAME fontID=8 name=User^5 .CMD DEFINE_FONTSTYLE_NAME fontID=9 name=User^6 .CMD DEFINE_FONTSTYLE_NAME fontID=10 name=User^7 .CMD DEFINE_FONTSTYLE fontID=0 family=Times^New^Roman points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=1 family=Times^New^Roman points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=2 family=Arial points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=4 family=Arial points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=5 family=Courier^New points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=6 family=System points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=7 family=Script points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=8 family=Roman points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=9 family=Modern points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD DEFINE_FONTSTYLE fontID=10 family=Times^New^Roman points=10 bold=0 italic=0 underline=0 colrid=-1 .CMD UNITS U=1 .CMD DIMENSIONS_ANALYSIS 0 0 .CMD COLORTAB_ENTRY 0 0 0 .CMD COLORTAB_ENTRY 128 0 0 .CMD COLORTAB_ENTRY 0 128 0 .CMD COLORTAB_ENTRY 128 128 0 .CMD COLORTAB_ENTRY 0 0 128 .CMD COLORTAB_ENTRY 128 0 128 .CMD COLORTAB_ENTRY 0 128 128 .CMD COLORTAB_ENTRY 128 128 128 .CMD COLORTAB_ENTRY 192 192 192 .CMD COLORTAB_ENTRY 255 0 0 .CMD COLORTAB_ENTRY 0 255 0 .CMD COLORTAB_ENTRY 255 255 0 .CMD COLORTAB_ENTRY 0 0 255 .CMD COLORTAB_ENTRY 255 0 255 .CMD COLORTAB_ENTRY 0 255 255 .CMD COLORTAB_ENTRY 255 255 255 .TXT 6 1 317 0 0 Cg b78.000000,78.000000,56 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red0\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard\qc {\fs24\b A Summary of Statistical Thermodynamic Calculation}{\fs24\b s}{\cf2\fs28 ©} \par \par by} .TXT 7 10 944 0 0 Cg a43.000000,43.000000,114 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard\qc Sidney Young\par \pard\qc Department of Chemistry\par University of South Alabama\par Mobile AL 36688-0002\par \par syoung@jaguar1.usouthal.edu} .TXT 0 35 942 0 0 Cg a37.000000,37.000000,118 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Theresa Julia Zielinski \par Department of Chemistry\par Niagara University\par Niagara University NY, 14109\par \par theresaz@localnet.com} .TXT 4 -8 943 0 0 Cg a36.000000,36.000000,3 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard and} .TXT 11 -37 935 0 0 Cg b78.000000,78.000000,214 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red0\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\fs18 © Copyright Sidney H. Young and Theresa Julia Zielinksi, 1997. All rights reserved.}{\cf2\fs18 You are welcome to use this document in your own classes but commercial use is not allowed without the permission of the author.}} .TXT 7 3 947 0 0 Cg a70.250000,70.250000,1972 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\b Introduction}: In this document the fundamental equations for calculating the thermodynamic properties of molecules and equilibrium constants for reactions are presented. You will see how the translation, rotational, vibrational and electronic states of molecules contribute to their thermodynamic properties. After studying this document you will be able to use the Mathcad equations as templates for determining the thermodynamic properties of molecules and reactions of interest to you and for your own projects. \par \par {\b Goal}: To provide students with the basic statistical thermodynamic equations for computing thermodynamic properties of molecules and reactions.\par \par {\b Prerequisites:}\par 1. Basic skills with Mathcad up to and including taking derivatives and using\par evaluate from the Symbolic drop down menu. \par 2. Knowledge of the existence of quantum mechanical energy levels; prior study \par of the classical ideas of translation, rotation, and vibrational modes that \par contribute to heat capacity. \par 3. Be able to distinguish between linear and nonlinear molecules.\par 4. Knowledge of the relationship between the Gibbs free energy and the \par equilibrium constant. \par \par {\b Performance Object}{\b ives}: \par 1. Compute the translational, rotational, vibrational, and electronic partition functions. \par 2. Compute A, U, S, G, etc. thermodynamic functions from the translational, rotational, \par vibrational, and electronic partition functions.\par 3. Compute the equilibrium constant for a reaction from the partition functions of \par the reactants and products.\par 4. Explain the shape of heat capacity as a function of temperature curves. \par 5. Identify the contribution from rotation, vibration, translation, and electronic \par degrees of freedom of the molecule or atom.\par 6. Explain the shape of heat capacity curves in terms of the degree of importance of the \par rotation, vibration, translation, and electronic degrees of freedom in the atom or molecule.} .TXT 63 -3 350 0 0 C x1,1,0,0 .TXT 4 4 544 0 0 Cg a65.000000,65.000000,87 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b Part I.}{ \cf2 \par }{\cf2\b \par Thermodynamic properties of molecular nitrogen from statistical thermodynamics}} .TXT 8 -1 543 0 0 Cg a67.000000,67.000000,273 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The first substance that we will study in this statistical mechanics exploration is molecular nitrogen. We will step through the process of determining the thermodynamic functions and heat capacity as a function of temperature. We will liberally use units in this exercise.} .TXT 9 0 366 0 0 Cg a70.000000,70.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard First define some constants:} .EQN 4 0 948 0 0 {0:N}NAME:6.02*(10)^(23) .TXT 0 15 367 0 0 Cg a55.000000,55.000000,17 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Avogadro's number} .EQN 5 -15 368 0 0 {0:k}NAME:1.38*(10)^(-23)*{0:joule}NAME*({0:K}NAME)^(-1) .EQN 0 22 369 0 0 {0:k}NAME={0}?_n_u_l_l_ .TXT 0 28 370 0 0 Cg a20.000000,20.000000,17 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Boltzman constant} .EQN 5 -50 371 0 0 {0:h}NAME:6.626*(10)^(-34)*{0:joule}NAME*{0:sec}NAME .EQN 0 22 372 0 0 {0:h}NAME={0}?_n_u_l_l_ .TXT 0 28 545 0 0 Cg a20.000000,20.000000,17 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Planck's constant} .EQN 7 -50 376 0 0 {0:mass}NAME:(.028)/({0:N}NAME)*{0:kg}NAME .EQN 0 22 377 0 0 {0:mass}NAME={0}?_n_u_l_l_ .TXT 0 26 546 0 0 Cg a21.000000,21.000000,16 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Mass of Nitrogen} .EQN 6 -49 411 0 0 {0:c}NAME:3.00*(10)^(8)*{0:m}NAME*({0:sec}NAME)^(-1) .EQN 0 23 412 0 0 {0:c}NAME={0}?_n_u_l_l_ .TXT 0 25 414 0 0 Cg a23.000000,23.000000,14 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Speed of light} .EQN 5 -47 397 0 0 {0:R}NAME:8.314*{0:joule}NAME*({0:K}NAME)^(-1) .EQN 0 18 398 0 0 {0:R}NAME={0}?_n_u_l_l_ .TXT 0 29 399 0 0 Cg a23.000000,23.000000,16 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The gas constant} .TXT 5 -48 396 0 0 Cg a70.000000,70.000000,69 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now set the properties of the gas, i.e. the temperature and pressure } .EQN 5 1 393 0 0 {0:T}NAME:300*{0:K}NAME .EQN 4 0 394 0 0 {0:P}NAME:1*{0:atm}NAME .EQN 0 17 395 0 0 {0:P}NAME={0}?_n_u_l_l_ .EQN 5 -17 400 0 0 {0:V}NAME:({0:R}NAME*{0:T}NAME)/({0:P}NAME) .EQN 0 18 401 0 0 {0:V}NAME={0}?_n_u_l_l_ .TXT 0 19 404 0 0 Cg a35.000000,35.000000,18 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Compute the volume} .TXT 8 -37 405 0 0 Cg a67.000000,67.000000,77 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b A. Calculating the Partition Functions}{\cf2 \par \par }1. The translation partition function} .EQN 10 1 406 0 0 {0:qt}NAME:(((2*{0:\p}NAME*{0:mass}NAME*{0:k}NAME*{0:T}NAME)/(({0:h}NAME)^(2))))^(1.5)*{0:V}NAME .EQN 0 21 407 0 0 {0:qt}NAME={0}?_n_u_l_l_ .TXT 7 -25 548 0 0 C x1,1,0,0 .TXT 4 4 408 0 0 Cg a65.000000,65.000000,34 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 2. The rotation partition function} .EQN 6 3 32 0 0 {0:B}NAME:2.010*({0:cm}NAME)^(-1) .EQN 1 17 549 0 0 {0:B}NAME={0}?_n_u_l_l_ .TXT 0 13 550 0 0 Cg a25.000000,25.000000,23 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Rotational Wave Numbers} .EQN 7 -30 421 0 0 {0:Thetar}NAME:({0:B}NAME*{0:c}NAME*{0:h}NAME)/({0:k}NAME) .TXT 4 34 551 0 0 Cg a23.000000,23.000000,37 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Thetar is the rotational temperature} .EQN 1 -17 424 0 0 {0:Thetar}NAME={0}?_n_u_l_l_ .EQN 8 -16 419 0 0 {0:qr}NAME:({0:T}NAME)/(2*{0:Thetar}NAME) .TXT 0 18 427 0 0 Cg a42.000000,42.000000,324 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The rotational partition function tells us the approximate number of populated states.\par \par {\cf2 On a separate worksheet calculate the rotational partition function for a series of diatomic gases and determine how the number of populated state varies as a function of mass and bond length. Why is bond length important here? Explain.}} .EQN 7 -18 425 0 0 {0:qr}NAME={0}?_n_u_l_l_ .TXT 15 0 50 0 0 Cg a65.000000,65.000000,36 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 3. The vibration partition function.} .EQN 6 0 552 0 0 {0:nu}NAME:2359.61*({0:cm}NAME)^(-1) .TXT 0 27 884 0 0 Cg a23.000000,23.000000,57 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard nu is the vibrational frequency of the nitrogen molecule.} .EQN 5 -19 558 0 0 {0:nu}NAME={0}?_n_u_l_l_ .EQN 4 -9 434 0 0 {0:Thetav}NAME:({0:h}NAME*{0:nu}NAME*{0:c}NAME)/({0:k}NAME) .TXT 0 24 885 0 0 Cg a32.500000,32.500000,41 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Thetav is the vibrational temperature. } .EQN 6 -16 559 0 0 {0:Thetav}NAME={0}?_n_u_l_l_ .EQN 9 -8 562 0 0 {0:qv}NAME:(1)/(1-({0:e}NAME)^((-{0:Thetav}NAME)/({0:T}NAME))) .TXT 1 20 886 0 0 Cg a39.000000,39.000000,237 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard qv is the vibrational partition function.\par \par {\cf2 What is the significance of having a large vibrational temperature? How does this correlate with the result computed here to the left that shows that the vibrational partition function qv=1. } } .EQN 8 -19 563 0 0 {0:qv}NAME={0}?_n_u_l_l_ .TXT 8 -8 565 0 0 C x1,1,0,0 .TXT 3 5 581 0 0 Cg a70.000000,70.000000,36 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 4. The electronic partition function} .EQN 6 2 593 0 0 {0:qe}NAME:1 .TXT 0 17 594 0 0 Cg a37.000000,37.000000,52 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Why is the electronic partition function equal to 1?}} .TXT 4 1 595 0 0 Cg a39.875000,39.875000,82 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard We explicitly include qe here to retain generality of the method in this document.} .EQN 7 -20 597 0 0 {0:q}NAME:{0:qt}NAME*{0:qr}NAME*{0:qv}NAME*{0:qe}NAME .TXT 0 20 596 0 0 Cg a37.000000,37.000000,95 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The total partition function is the product of the four contributing partition functions. } .EQN 6 -20 588 0 0 {0:q}NAME={0}?_n_u_l_l_ .TXT 3 21 473 0 0 Cg a46.000000,46.000000,203 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Q is the canonical ensemble molar partition function. It is this quantity that is connected to the thermodynamic property known as the Helmholtz free energy. Q is so large that we can only calculate lnQ.} .EQN 12 -22 602 0 0 {0:lnQ}NAME:{0:N}NAME*{0:ln}NAME({0:q}NAME)-{0:N}NAME*{0:ln}NAME({0:N}NAME)+{0:N}NAME .TXT 0 25 829 0 0 Cg a44.000000,44.000000,77 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Using Sterling's approximation show that }{\object{\*\objclass \eqn} \rsltpict{\*\objdata .EQN 336 57 830 0 0 {0:Q}NAME÷(({0:q}NAME)^({0:n}NAME))/(({0:n}NAME)!) }}{\cf2 leads to the equation on the left.}} .TXT 10 -3 591 0 0 Cg a46.000000,46.000000,157 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now that we have lnQ we can calculate the thermodynamic properties of nitrogen gas at the temperature and pressure specified near the top of this document. } .EQN 3 -22 831 0 0 {0:lnQ}NAME={0}?_n_u_l_l_ .TXT 4 -4 589 0 0 C x1,1,0,0 .TXT 3 3 476 0 0 Cg a64.000000,64.000000,43 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b B. Calculating the Thermodynamic Properties}} .TXT 4 3 604 0 0 Cg a26.000000,26.000000,24 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 1. Helmholtz free energy} .EQN 4 7 485 0 0 {0:A}NAME:-{0:k}NAME*{0:T}NAME*{0:lnQ}NAME .EQN 0 19 486 0 0 {0:A}NAME={0}?_n_u_l_l_ .TXT 4 -26 606 0 0 Cg a70.000000,70.000000,18 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 2. Internal Energy} .TXT 4 30 487 0 0 Cg a51.000000,51.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\fs16 Notice how u is defined here}} .EQN 1 -19 488 0 0 {0:u}NAME:({0:Thetav}NAME)/({0:T}NAME) .EQN 6 1 489 0 0 {0:E}NAME:(3)/(2)*{0:R}NAME*{0:T}NAME+{0:R}NAME*{0:T}NAME+({0:R}NAME*{0:Thetav}NAME)/(({0:e}NAME)^({0:u}NAME)-1) .EQN 6 6 609 0 0 {0:E}NAME={0}?_n_u_l_l_ .TXT 5 -18 608 0 0 Cg a70.000000,70.000000,10 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 3. Entropy} .EQN 3 9 632 0 0 {0:S}NAME:({0:E}NAME-{0:A}NAME)/({0:T}NAME) .EQN 3 10 633 0 0 {0:S}NAME={0}?_n_u_l_l_ .TXT 3 0 634 0 0 Cg a33.000000,33.000000,16 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Lit value: 191.6}} .TXT 5 -20 614 0 0 Cg a70.000000,70.000000,35 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 4. The heat capacities, C{ \dn v }and C{\dn p} } .EQN 7 6 85 0 0 {0:Cv}NAME:(3)/(2)*{0:R}NAME+{0:R}NAME+({0:R}NAME*({0:u}NAME)^(2)*({0:e}NAME)^({0:u}NAME))/(((({0:e}NAME)^({0:u}NAME)-1))^(2)) .TXT 0 27 839 0 0 Cg a35.000000,35.000000,72 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard See below for the derivation of the of the vibration heat capacity term.} .EQN 6 -27 833 0 0 {0:Cv}NAME={0}?_n_u_l_l_ .EQN 4 0 832 0 0 {0:Cp}NAME:{0:Cv}NAME+{0:R}NAME .EQN 1 26 836 0 0 {0:Cp}NAME={0}?_n_u_l_l_ .TXT 3 0 840 0 0 Cg a34.000000,34.000000,16 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Lit value: 29.06}} .TXT 4 -33 615 0 0 Cg a71.000000,71.000000,34 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 5. Enthalpy and Gibbs free energy.} .EQN 4 7 616 0 0 {0:H}NAME:{0:E}NAME+{0:R}NAME*{0:T}NAME .EQN 2 18 623 0 0 {0:H}NAME={0}?_n_u_l_l_ .EQN 3 -18 621 0 0 {0:G}NAME:{0:H}NAME-{0:T}NAME*{0:S}NAME .EQN 1 18 624 0 0 {0:G}NAME={0}?_n_u_l_l_ .TXT 5 -25 628 0 0 Cg a68.000000,68.000000,35 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard 6. The Helmholtz free energy again.} .EQN 3 6 629 0 0 {0:A}NAME:{0:E}NAME-{0:T}NAME*{0:S}NAME .EQN 0 14 841 0 0 {0:A}NAME={0}?_n_u_l_l_ .TXT 4 -1 844 0 0 Cg a39.625000,39.625000,90 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Compare with above. This is a redundancy confirmation to check that everything is working.}} .TXT 5 -23 635 0 0 C x1,1,0,0 .TXT 6 5 318 0 0 Cg a60.500000,60.500000,197 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b Part II. Mathematical Interlude}:\par \par Below we see the derivation of the vibrational contribution to the heat capacity. This shows how the vibration term arises from the vibration partition function. } .EQN 14 -1 517 0 0 {0:qv}NAME÷(1)/(1-({0:e}NAME)^((-{0:Thetav}NAME)/({0:T}NAME))) .TXT 0 20 636 0 0 Cg a44.000000,44.000000,116 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Start with the definition of the vibration partition function and use the ctrl = key sequence to write the equation.} .EQN 12 -20 520 0 0 {0:E}NAME÷{0:R}NAME*({0:T}NAME)^(2)*{0:T}NAME"{0:ln}NAME({0:qv}NAME) .TXT 0 20 887 0 0 Cg a44.000000,44.000000,81 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we write the definition of E in terms of the vibrational partition function.} .TXT 10 5 638 0 0 Cg a37.375000,37.375000,170 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard You can obtain this equation by replacing qv by is equivalent defined above using cut and paste. Then symbolically evaluate the derivative as described immediately below.} .EQN 1 -25 516 0 0 {0:E}NAME÷{0:R}NAME*({0:T}NAME)^(2)*{0:T}NAME"{0:ln}NAME((1)/(1-({0:e}NAME)^((-{0:Thetav}NAME)/({0:T}NAME)))) .TXT 15 28 640 0 0 Cg a36.000000,36.000000,215 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard This is obtained by placing the selection box around the derivative part of the equation just above and choosing Evaluate followed by using Evaluate Symbolically from the Symbolic menu. {\cf2 Try these steps for practice.}} .EQN 2 -30 639 0 0 {0:E}NAME÷-{0:R}NAME*{0:Thetav}NAME*({0:exp}NAME((-{0:Thetav}NAME)/({0:T}NAME)))/((-1+{0:exp}NAME((-{0:Thetav}NAME)/({0:T}NAME)))) .TXT 12 1 888 0 0 Cg a65.000000,65.000000,23 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard by substitution, yields} .TXT 7 34 647 0 0 Cg a24.375000,24.375000,54 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Use cut and past to generate the equation to the left.} .EQN 1 -35 645 0 0 {0:E}NAME÷(({0:R}NAME)/((1-{0:exp}NAME(-{0:u}NAME)))*{0:u}NAME*{0:T}NAME*{0:exp}NAME(-{0:u}NAME)÷({0:R}NAME*{0:u}NAME*{0:T}NAME)/(({0:e}NAME)^({0:u}NAME)-1)) .TXT 5 -2 661 0 0 C x1,1,0,0 .TXT 3 3 655 0 0 Cg a69.000000,69.000000,70 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard We can now extend the derivation to obtain the heat capacity equation.} .TXT 6 1 656 0 0 Cg a69.000000,69.000000,13 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Starting with} .EQN 0 14 657 0 0 {0:E}NAME÷(5)/(2)*{0:R}NAME*{0:T}NAME+({0:R}NAME*{0:u}NAME*{0:T}NAME)/((({0:e}NAME)^({0:u}NAME)-1)) .TXT 0 17 659 0 0 Cg a38.000000,38.000000,5 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard where} .EQN 0 9 660 0 0 {0:u}NAME÷({0:Thetav}NAME)/({0:T}NAME) .TXT 8 -40 663 0 0 Cg a69.000000,69.000000,26 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Substituting for u yields } .EQN 1 21 665 0 0 {0:E}NAME÷(5)/(2)*{0:R}NAME*{0:T}NAME+{0:R}NAME*({0:Thetav}NAME)/(({0:exp}NAME(({0:Thetav}NAME)/({0:T}NAME))-1)) .TXT 10 -21 666 0 0 Cg a69.000000,69.000000,52 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Next take the derivative with respect to T to obtain} .TXT 1 49 845 0 0 Cg a20.000000,20.000000,34 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Do this step to verify the result.} .EQN 6 -45 112 0 0 {0:Cv}NAME÷(5)/(2)*{0:R}NAME+{0:R}NAME*(({0:Thetav}NAME)^(2))/(((({0:exp}NAME(({0:Thetav}NAME)/({0:T}NAME))-1))^(2)*({0:T}NAME)^(2)))*{0:exp}NAME(({0:Thetav}NAME)/({0:T}NAME)) .EQN 1 43 117 0 0 {0:Thetav}NAME÷{0:u}NAME*{0:T}NAME .TXT 10 -44 667 0 0 Cg a65.000000,65.000000,23 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard by substitution, yields} .EQN 7 3 670 0 0 {0:Cv}NAME÷(5)/(2)*{0:R}NAME+{0:R}NAME*(({0:u}NAME)^(2))/((({0:exp}NAME({0:u}NAME)-1))^(2))*{0:exp}NAME({0:u}NAME) .TXT 9 -10 671 0 0 C x1,1,0,0 .TXT 6 2 672 0 0 Cg a69.000000,69.000000,90 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b Part III. Obtaining the equilibrium constant for N}{\cf2\b\dn 2}{\cf2\b <---> 2 N as a function of temperature}} .TXT 6 2 673 0 0 Cg a69.000000,69.000000,138 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard First obtain the partition function for each component of the equilibrium. In this case we need the partition function for both N{\dn 2} and N. } .EQN 10 0 143 0 0 {0:qN2}NAME({0:T}NAME):(((2*{0:\p}NAME*{0:mass}NAME*{0:k}NAME*{0:T}NAME)/(({0:h}NAME)^(2))))^(1.5)*{0:V}NAME*({0:T}NAME)/(2*{0:Thetar}NAME)*(1)/(1-({0:e}NAME)^((-{0:Thetav}NAME)/({0:T}NAME)))*1 .TXT 0 43 674 0 0 Cg a19.750000,19.750000,29 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The partition function for N{\dn 2}} .EQN 9 -42 157 0 0 {0:massN}NAME:(.014)/({0:N}NAME)*{0:kg}NAME .TXT 0 22 684 0 0 Cg a46.000000,46.000000,27 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The mass of atomic nitrogen} .TXT 6 -21 686 0 0 Cg a47.625000,47.625000,54 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now compute the atomic partition function for atomic N} .EQN 7 -3 160 0 0 {0:qN}NAME({0:T}NAME):(((2*{0:\p}NAME*{0:massN}NAME*{0:k}NAME*{0:T}NAME)/(({0:h}NAME)^(2))))^(1.5)*{0:V}NAME*(4+6*({0:e}NAME)^((-27658.7*{0:K}NAME)/({0:T}NAME))+4*({0:e}NAME)^((-27671.7*{0:K}NAME)/({0:T}NAME))+6*({0:e}NAME)^((-41492.4*{0:K}NAME)/( {0:T}NAME))) .TXT 6 6 889 0 0 Cg a62.500000,62.500000,435 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Immediately above is the partition function for atomic nitrogen. It includes contributions from the first three excited states.\par \par Note: This can be coupled to determination of the term symbols for the states of nitrogen as a link between statistical thermodynamics and spectroscopy. {\cf2 Recompute the partition function without the highest energy level term. Decide if this energy level is essential in the final heat capacity calculation }} .EQN 18 -6 161 0 0 {0:lnQN2}NAME({0:T}NAME):{0:N}NAME*{0:ln}NAME({0:qN2}NAME({0:T}NAME))-{0:N}NAME*{0:ln}NAME({0:N}NAME)+{0:N}NAME .TXT 0 36 324 0 0 Cg a22.125000,22.125000,66 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we are computing the natural log of molar partition functions} .EQN 4 -36 162 0 0 {0:lnQN}NAME({0:T}NAME):{0:N}NAME*{0:ln}NAME({0:qN}NAME({0:T}NAME))-{0:N}NAME*{0:ln}NAME({0:N}NAME)+{0:N}NAME .EQN 7 1 165 0 0 {0:AN2}NAME({0:T}NAME):-{0:k}NAME*{0:T}NAME*{0:lnQN2}NAME({0:T}NAME) .TXT 0 28 849 0 0 Cg a36.000000,36.000000,80 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now we calculate the Helmholtz free energy for each component of the equilibrium} .EQN 5 -28 166 0 0 {0:AN}NAME({0:T}NAME):-{0:k}NAME*{0:T}NAME*{0:lnQN}NAME({0:T}NAME) .EQN 6 1 699 0 0 {0:GN2}NAME({0:T}NAME):{0:AN2}NAME({0:T}NAME)+{0:R}NAME*{0:T}NAME .TXT 0 28 702 0 0 Cg a36.000000,36.000000,199 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we calculate the Gibbs free energy. Using what you know and your text explain why the equation to calculate the Gibbs free energy is different from that used for the molecular nitrogen example. } .EQN 6 -28 700 0 0 {0:GN}NAME({0:T}NAME):{0:AN}NAME({0:T}NAME)+{0:R}NAME*{0:T}NAME .TXT 5 -5 745 0 0 C x1,1,0,0 .TXT 7 4 744 0 0 Cg a69.000000,69.000000,21 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now calculate delta G} .EQN 4 0 169 0 0 {0:Delta_G}NAME({0:T}NAME):(2*{0:GN}NAME({0:T}NAME)-{0:GN2}NAME({0:T}NAME))+(9.756*1.6*(10)^(-19)*{0:N}NAME*{0:joule}NAME) .TXT 5 8 891 0 0 Cg a52.875000,52.875000,250 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The third term in the expression for the change in Gibbs free energy is necessary because the bottoms of the potential energy functions of the products and reactants do not match. One is displaced from the of the other by the dissociation energy D{\dn o}. } .TXT 14 16 850 0 0 Cg a42.500000,42.500000,196 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Calculate the equilibrium constant and the value of the equilibrium constant at several temperatures. How does K vary with temperature? How does the equilibrium shift with increasing temperature?}} .EQN 1 -22 706 0 0 {0:Keq}NAME({0:T}NAME):({0:e}NAME)^((-{0:Delta_G}NAME({0:T}NAME))/({0:R}NAME*{0:T}NAME)) .EQN 6 0 708 0 0 {0:Keq}NAME(300*{0:K}NAME)={0}?_n_u_l_l_ .EQN 6 0 720 0 0 {0:Keq}NAME(1000*{0:K}NAME)={0}?_n_u_l_l_ .EQN 4 0 722 0 0 {0:Keq}NAME(8000*{0:K}NAME)={0}?_n_u_l_l_ .TXT 6 15 893 0 0 Cg a45.000000,45.000000,126 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 At what temperature does this reaction become spontaneous? What is K at the point where the reaction just becomes spontaneous?}} .TXT 12 6 851 0 0 Cg a42.000000,42.000000,485 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard To answer this question you want to find the temperature where the equilibrium constant equals 1. To do this we can set up a solve block. Make an initial guess for this temperature based on your observations on how the equilibrium constant varies with temperature. Here we have chosen T to be 8000 K. Next set up the solve block using the Given statement. Set the condition for the solution and then use the Find function. If you have a good guess then the temperature will be found. } .EQN 3 -17 894 0 0 {0:T}NAME:8000*{0:K}NAME .EQN 4 -6 733 0 0 {0:Given}NAME .EQN 4 6 896 0 0 {0:Keq}NAME({0:T}NAME)÷1 .EQN 5 0 895 0 0 {0:Tout}NAME:{0:Find}NAME({0:T}NAME) .EQN 8 0 741 0 0 {0:Tout}NAME={0}?_n_u_l_l_ .TXT 0 21 742 0 0 Cg a42.000000,42.000000,58 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we have the temperature and the equilibrium constant.} .EQN 4 -21 740 0 0 {0:Keq}NAME({0:Tout}NAME)={0}?_n_u_l_l_ .TXT 2 -10 743 0 0 C x1,1,0,0 .TXT 5 5 199 0 0 Cg a68.000000,68.000000,67 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b Part IV. Heat Capacity of a Linear Polyatomic, CO}{\cf2\b\dn 2}{\cf2\b , at 15 C, 1 atm.}} .EQN 5 0 751 0 0 {0:T}NAME:293*{0:K}NAME .EQN 5 0 752 0 0 {0:Cvt}NAME:(3)/(2)*{0:R}NAME .TXT 0 33 897 0 0 Cg a34.000000,34.000000,130 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 How many modes of vibration are present in CO}{\cf2\dn 2}{\cf2 ? Are there degenerate modes? What are the vibrational temperatures for these modes?}} .EQN 3 -19 754 0 0 {0:Thetav}NAME:({4,1}ö960*{0:K}NAMEö960*{0:K}NAMEö3380*{0:K}NAMEö1997*{0:K}NAME) .EQN 2 -14 753 0 0 {0:Cvr}NAME:{0:R}NAME .TXT 14 31 852 0 0 Cg a28.000000,28.000000,134 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we compute the vibrational contribution to the heat capacity. This is an extension of the formula we used for nitrogen gas above.} .EQN 1 -32 219 0 0 {0:Cvv}NAME:{0:R}NAME*((0,3,{0:i}NAME,((((({0:Thetav}NAME)[({0:i}NAME))/({0:T}NAME)))^(2)*({0:e}NAME)^(((({0:Thetav}NAME)[({0:i}NAME))/({0:T}NAME))))/(((({0:e}NAME)^(((({0:Thetav}NAME)[({0:i}NAME))/({0:T}NAME)))-1))^(2))){64}) .EQN 10 0 756 0 0 {0:Cvv}NAME={0}?_n_u_l_l_ .EQN 6 0 762 0 0 {0:Cvtot}NAME:{0:Cvt}NAME+{0:Cvr}NAME+{0:Cvv}NAME .EQN 4 0 758 0 0 {0:Cvtot}NAME={0}?_n_u_l_l_ .TXT 0 30 900 0 0 Cg a32.750000,32.750000,40 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we compute the total heat capacity.} .TXT 4 -29 899 0 0 Cg a31.000000,31.000000,10 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Lit: 28.09}} .TXT 5 -5 767 0 0 C x1,1,0,0 .TXT 5 3 766 0 0 Cg a68.000000,68.000000,69 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b Part V. Heat Capacity of a nonlinear Polyatomic, H}{\cf2\b\dn 2}{\cf2\b O}{ \cf2\b , at 15 C, 1 atm.}} .EQN 6 1 230 0 0 {0:Cvt}NAME:(3)/(2)*{0:R}NAME .TXT 0 22 901 0 0 Cg a40.000000,40.000000,46 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Translation contribution to the heat capacity.} .EQN 7 -22 768 0 0 {0:Cvt}NAME={0}?_n_u_l_l_ .TXT 7 22 902 0 0 Cg a40.000000,40.000000,140 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Rotational contribution to the heat capacity. Why is the rotational contribution to the heat capacity for water different from that for CO{\dn 2}?} .EQN 2 -21 231 0 0 {0:Cvr}NAME:(3)/(2)*{0:R}NAME .EQN 7 0 770 0 0 {0:Cvr}NAME={0}?_n_u_l_l_ .TXT 8 26 903 0 0 Cg a31.625000,31.625000,100 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 How are the number of modes of vibration for H}{\cf2\dn 2}{\cf2 O different from the number of modes for CO}{\cf2\dn 2}{\cf2 and why?}} .EQN 2 -25 232 0 0 {0:Thetav}NAME:({3,1}ö5404*{0:K}NAMEö2995*{0:K}NAMEö5254*{0:K}NAME) .EQN 15 -1 778 0 0 {0:Cvv}NAME:{0:R}NAME*((0,2,{0:i}NAME,((((({0:Thetav}NAME)[({0:i}NAME))/({0:T}NAME)))^(2)*({0:e}NAME)^(((({0:Thetav}NAME)[({0:i}NAME))/({0:T}NAME))))/(((({0:e}NAME)^(((({0:Thetav}NAME)[({0:i}NAME))/({0:T}NAME)))-1))^(2))){64}) .TXT 0 32 780 0 0 Cg a27.875000,27.875000,71 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we are computing the vibrational contribution to the heat capacity} .EQN 12 -31 777 0 0 {0:Cvv}NAME={0}?_n_u_l_l_ .EQN 8 1 238 0 0 {0:Cvtot}NAME:{0:Cvt}NAME+{0:Cvr}NAME+{0:Cvv}NAME .TXT 0 31 785 0 0 Cg a35.000000,35.000000,40 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we compute the total heat capacity.} .EQN 5 -31 783 0 0 {0:Cvtot}NAME={0}?_n_u_l_l_ .TXT 4 0 784 0 0 Cg a31.000000,31.000000,10 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 Lit: 25.28}} .TXT 4 -7 786 0 0 C x1,1,0,0 .TXT 4 8 787 0 0 Cg a64.000000,64.000000,124 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red255\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2\b Part VI. The strange case of NO: The effect of a low-lying electronic \par energy level on the heat capacity of NO.}} .EQN 6 0 788 0 0 {0:Cvt}NAME:(3)/(2)*{0:R}NAME .TXT 0 19 789 0 0 Cg a46.000000,46.000000,29 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The translation contribution.} .TXT 5 0 791 0 0 Cg a46.000000,46.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The rotational contribution.} .EQN 1 -19 790 0 0 {0:Cvr}NAME:{0:R}NAME .EQN 6 0 927 0 0 {0:Thetav}NAME:(1904.20*({0:cm}NAME)^(-1)*{0:c}NAME*{0:h}NAME)/({0:k}NAME) .TXT 1 30 795 0 0 Cg a35.000000,35.000000,28 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard The vibrational temperature.} .EQN 5 -30 928 0 0 {0:Thetav}NAME={0}?_n_u_l_l_ .EQN 7 -4 904 0 0 {0:Cvv}NAME({0:T}NAME):{0:R}NAME*(({0:Thetav}NAME)^(2))/(((({0:exp}NAME(({0:Thetav}NAME)/({0:T}NAME))-1))^(2)*({0:T}NAME)^(2)))*{0:exp}NAME(({0:Thetav}NAME)/({0:T}NAME)) .TXT 0 41 905 0 0 Cg a24.000000,24.000000,58 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard This is the vibrational contribution to the heat capacity.} .TXT 10 -42 906 0 0 Cg a70.000000,70.000000,643 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now we will consider the electronic partition function for the NO molecule. This molecule has one unpaired electron in the highest occupied molecular orbital. The molecular term symbol is a doublet. Also there is a low lying excited state molecular orbital. This level is sufficiently low so that a significant population of molecules have the single electron in this energy level. This energy level will be singly occupied and thus have a doublet molecular term symbol. Since both of these levels are doublets they have a degeneracy of 2. Higher energy molecular orbitals are not populated so they do not contribute to the partition function.} .TXT 18 22 911 0 0 Cg a41.625000,41.625000,228 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we write the Mathcad numerical definition of the partition function for electronic partition function. The first term on the right hand side of this equation is for the ground state. Why is this term simply the integer 2? } .EQN 2 -21 909 0 0 {0:qe}NAME:2+2*({0:e}NAME)^((-174.2*{0:K}NAME)/({0:T}NAME)) .TXT 9 22 914 0 0 Cg a38.875000,38.875000,85 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Here we have the electronic partition function written in the Mathcad symbolic form. } .EQN 4 -22 917 0 0 {0:qe}NAME({0:T}NAME)÷2+2*({0:e}NAME)^((-174.2*{0:K}NAME)/({0:T}NAME)) .TXT 1 22 916 0 0 Cg a40.000000,40.000000,122 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Place the blue selection cursor next to the T in the equation and choose differentiate on variable from the Symbolic menu.} .TXT 7 0 949 0 0 Cg a34.875000,34.875000,82 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\fs16 Note: you can take the derivative of a symbolic but not of a numerical definition.}} .TXT 5 0 924 0 0 Cg a65.000000,65.000000,56 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard This yields the following equation. {\cf2 Try it for yourself.}} .EQN 5 -22 925 0 0 {0:T}NAME"{0:qe}NAME({0:T}NAME)÷348.4*({0:K}NAME)/(({0:T}NAME)^(2))*{0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME)) .TXT 5 -4 929 0 0 C x1,1,0,0 .TXT 5 35 814 0 0 Cg a38.000000,38.000000,49 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Create the equation on the left by cut and paste.} .EQN 5 -32 926 0 0 {0:Ue}NAME({0:T}NAME)÷({0:R}NAME*({0:T}NAME)^(2)*((348.4*{0:K}NAME)/(({0:T}NAME)^(2))*{0:exp}NAME((-174.2)/({0:T}NAME))))/(2+2*({0:e}NAME)^((-174.2*{0:K}NAME)/({0:T}NAME))) .TXT 0 34 930 0 0 Cg a31.000000,31.000000,76 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 What is the electronic heat capacity in the limit of very high temperatures?}} .TXT 10 -34 931 0 0 Cg a66.000000,66.000000,76 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Select the equation above and choose Symbolic Simplify to get the following:} .EQN 10 4 825 0 0 {0:Ue}NAME({0:T}NAME)÷174.2*{0:R}NAME*{0:K}NAME*({0:exp}NAME((-174.2)/({0:T}NAME)))/((1.+{0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME)))) .TXT 11 -1 299 0 0 Cg a67.000000,67.000000,97 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard differentiation yields ({\cf2 Verify the result shown here by using the appropriate Mathcad procedure.})} .EQN 11 0 300 0 0 {0:T}NAME"{0:Ue}NAME({0:T}NAME)÷30345.64*{0:R}NAME*(({0:K}NAME)^(2))/(({0:T}NAME)^(2))*({0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME)))/((1.+{0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME))))-30345.64*{0:R}NAME*({0:K}NAME)^(2)*(({0:exp}NAME(-174.2*({0:K}NAME)/( {0:T}NAME)))^(2))/((((1.+{0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME))))^(2)*({0:T}NAME)^(2))) .TXT 8 0 301 0 0 Cg a67.000000,67.000000,13 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard simplifies to} .EQN 7 0 302 0 0 {0:T}NAME"{0:Ue}NAME({0:T}NAME)÷30345.64*{0:R}NAME*({0:K}NAME)^(2)*({0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME)))/((((1.+{0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME))))^(2)*({0:T}NAME)^(2))) .TXT 9 39 932 0 0 Cg a26.000000,26.000000,58 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Cut and paste to create the numeric heat capacity equation} .EQN 7 -39 303 0 0 {0:Cve}NAME({0:T}NAME):30345.64*{0:R}NAME*({0:K}NAME)^(2)*({0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME)))/((((1.+{0:exp}NAME(-174.2*({0:K}NAME)/({0:T}NAME))))^(2)*({0:T}NAME)^(2))) .TXT 8 -6 950 0 0 C x1,1,0,0 .TXT 3 7 860 0 0 Cg a66.000000,66.000000,71 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now compute the total heat capacity and each of the contributing terms.} .EQN 6 1 862 0 0 {0:Cvt}NAME={0}?_n_u_l_l_ .EQN 4 5 863 0 0 {0:Cvr}NAME={0}?_n_u_l_l_ .EQN 4 7 864 0 0 {0:Cvv}NAME(100*{0:K}NAME)={0}?_n_u_l_l_ .EQN 4 9 865 0 0 {0:Cve}NAME(100*{0:K}NAME)={0}?_n_u_l_l_ .EQN 5 -24 871 0 0 {0:Cv}NAME({0:T}NAME):{0:Cvt}NAME+{0:Cvr}NAME+{0:Cvv}NAME({0:T}NAME)+{0:Cve}NAME({0:T}NAME) .EQN 5 0 869 0 0 {0:Cv}NAME(40*{0:K}NAME)={0}?_n_u_l_l_ .EQN 4 0 870 0 0 {0:Cvne}NAME({0:T}NAME):{0:Cvt}NAME+{0:Cvr}NAME+{0:Cvv}NAME({0:T}NAME) .TXT 0 27 877 0 0 Cg a40.000000,40.000000,42 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Heat capacity without the electronic term.} .EQN 4 -27 872 0 0 {0:Cvnv}NAME({0:T}NAME):{0:Cvt}NAME+{0:Cvr}NAME+{0:Cve}NAME({0:T}NAME) .TXT 0 27 876 0 0 Cg a40.000000,40.000000,43 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Heat capacity without the vibrational term.} .TXT 9 -32 880 0 0 C x1,1,0,0 .TXT 8 3 879 0 0 Cg a70.000000,70.000000,79 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard Now we systematically vary the temperature and examine the results graphically.} .TXT 5 27 934 0 0 Cg a36.250000,36.250000,215 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard At very low temperatures the electronic contribution to the heat capacity dominates and saturates as shown by the peak in the graph. The heat capacity then declines to a minimum until the vibration term kicks in. } .EQN 1 -23 868 0 0 {0:i}NAME:20,40;1000 .EQN 11 -3 881 0 0 &&(_n_u_l_l_&_n_u_l_l_)&{0:Cv}NAME({0:i}NAME*{0:K}NAME),{0:Cvne}NAME({0:i}NAME*{0:K}NAME),{0:Cvnv}NAME({0:i}NAME*{0:K}NAME),{0:Cve}NAME({0:i}NAME*{0:K}NAME)@&&(_n_u_l_l_&_n_u_l_l_)&{0:i}NAME 0 0 1 1 1 0 0 1 1 0 0 1 1 1 0 0 1 1 0 1 0 0 1 1 NO-TRACE-STRING 0 2 1 0 1 1 NO-TRACE-STRING 0 3 2 0 1 1 NO-TRACE-STRING 0 4 3 0 1 1 NO-TRACE-STRING 0 1 4 0 1 1 NO-TRACE-STRING 0 2 5 0 1 1 NO-TRACE-STRING 0 3 6 0 1 1 NO-TRACE-STRING 0 4 0 0 1 1 NO-TRACE-STRING 0 1 1 0 1 1 NO-TRACE-STRING 0 2 2 0 1 1 NO-TRACE-STRING 0 3 3 0 1 1 NO-TRACE-STRING 0 4 4 0 1 1 NO-TRACE-STRING 0 1 5 0 1 1 NO-TRACE-STRING 0 2 6 0 1 1 NO-TRACE-STRING 0 3 0 0 1 1 NO-TRACE-STRING 0 4 1 0 1 1 NO-TRACE-STRING 0 1 1 21 18 10 0 3 .TXT 4 38 882 0 0 Cg a24.000000,24.000000,165 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\ul Figure legend}.\par \par Cvne is the heat capacity with no electronic term\par \par Cvnv is without the vibration term.\par \par Cve is electronic term alone. \par \par Cv is the total heat capacity.} .TXT 25 -38 883 0 0 Cg a56.000000,56.000000,225 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;\red128\green0\blue0;}{ \fonttbl{\f0\fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\cf2 By inspection of the graph describe where the electronic contribution is most important and how this contribution changes with temperature. Why is this happening? When does the vibrational contribution become important? Why? }} .TXT 10 -1 953 0 0 Cg a74.000000,74.000000,507 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard {\b Mastery Exercise:} \par \par The energy levels for an electron constrained to move on a ring with a diameter of 0.4 nm\par \par are given by {\object{ \*\objclass \eqn}\rsltpict{\*\objdata .EQN 1268 13 952 0 0 {0:E.n}NAME÷(({0:hbar}NAME)^(2)*({0:n}NAME)^(2))/(2*{0:m}NAME*({0:d}NAME)^(2)) }} where n is the quantum number identifying the energy level, m is the mass of the electron and d is the diameter of the ring. Write the expression for the partition function for the electron on the ring. At room temperature would the electronic partition function for this system contribute significantly to the heat capacity. Explain by providing graphical or arithmetic evidence. } .TXT 23 -3 954 0 0 Cg b78.000000,78.000000,306 {\rtf\ansi \deff0{\colortbl;\red0\green0\blue128;}{\fonttbl{\f0 \fcharset0\fnil Arial;}}\plain\cf1\fs20 \pard \par {\b Acknowlegment}: The authors acknowledges the National Science Foundation for support of the 1997 NSF-UFE Workshop on "Numerical Methods in the Undergraduate Chemistry Curriculum Using the Mathcad Software" and the organizers (Jeff Madura, Andrzej Wierzbicki and Sidney Young, University of South Alabama).\par }