Uses of Cp Equations

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Uses of Cp Equations
?Hs(298 K) ?Hv(298 K) ?Hfus(298 K) The
fusion, vaporization and sublimation enthalpies
of biphenyl are given below. Evaluate these
thermodynamic properties at T 298.15 K and
check to see that they are internally
consistent. ?Hs(311 K) 82.5 kJ mol-1 ?Hv(363 K)
59.6 kJ mol-1 ?Hfus(341.5 K) 18.66 kJ
mol-1 ?Hs ? 59.6 18.7 78.3 kJ mol-1
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Biphenyl ?Hs(311 K) 82.5 kJ mol-1 ?Hs(298 K)
?Hs(311 K)(0.710.15 Cp(c)calc)311-298 Cp(c)cal
c 1017.528.5 Cp(c)calc 192 J mol-1
K-1 ?Hs(298 K) 82.5 (0.38 ?0.1) ?Hs(298 K)
(82.9?0.1) kJ mol-1
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Biphenyl ?Hs(298 K) (82.9?0.1) kJ mol-1
?Hv(363 K) 59.6 kJ mol-1 ?Hv(298 K) ?Hv(363
K) (10.580.26 Cp(l)calc)363-298 Cp(l)calc
1021.8215.3 Cp(l)calc 248.6 J mol-1
K-1 ?Hv(298 K) 59.6 (4.88 ? 0.98) ?Hv(298 K)
(64.5 ? 1.0) kJ mol-1
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Biphenyl ?Hs(298 K) 82.9 kJ mol-1 ?Hv(298 K)
64.5?1.0 kJ mol-1
?Hfus(341.5 K) 18.66 kJ mol-1 ?Hfus(298 K)
?Hfus(341.5 K) )0.15Cp(c) - 0.26Cp(l)-
9.83Tfus-298 ?Hfus(298 K) 18.66 -(1.98?0.6)
?Hfus(298 K) (16.7?0.6) kJ mol-1 ?Hs(298 K)
(64.5?1.0) (16.7?0.6) ?Hs(298 K) (81.2
?1.2) kJ mol-1
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NIST Webbook A valuable source of thermochemical
information http//webbook.nist.gov/chemistry/
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The vaporization enthalpy of anthracene has been
measured over the temperature range T 496-555
K ?Hv 59200 ? 200 J mol-1. The fusion enthalpy
was measured as ?Hfus (489K) 29370 ? 100 J
mol-1. What is the sublimation enthalpy of
anthracene at T 298.15 K?
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Estimation of Vaporization Enthalpies
1. Group additivity by Guthrie and Taylor Can J.
Chem.1983, 61, 602-607. 2. Group additivity by
Ducros, M. Gruson, J. F. Sannier, H.
Thermochimica Acta 1980, 36, 39-65 Ducros, M.,
Gruson, J.F., and Sannier, H., Thermochimica
Acta, 1981, 44, 131-140. DuCros, M. Sanier, H.
Thermochim. Acta 1982, 54, 153-157 Ducros, M.
Sannier, H. Thermochimica Acta 1984, 75,
329-340. 3. Group Additivity of Chickos, J.
S.Acree, Jr. W. E. Liebman, J. F.
Computational Thermochemistry, Irikura, K. K.
Frurip, D. J. Edit. ACS 1996.
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?Hv(298) Estimation of Hydrocarbons ?Hv(298)/kJmol
-14.69(nC -nQ)1.3nQ 3.0 nQ refers to a
quaternary sp3 carbon atom ?Hv(298)Estimation of
Monosubstituted Hydrocarbon Derivatives ?Hv(298)/k
Jmol-14.69(nC -nQ)1.3nQ3.0nMM b C
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?Hv(298) Estimation of Hydrocarbons
Estimate ?Hv(298) for cycloheptatriene ?Hv(298)4.
69(nC -nQ)1.3nQ 3.0 ?Hv(298) 39.4 kJmol-1
(literature) Estimate ?Hv(298) for
2-nitrotoluene ? Hv(298) 59.1 kJmol-1
(literature)
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?Hv(298) Estimation of Polysubstituted
Hydrocarbon Derivatives
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?Hv(298) Estimation of Polysubstituted
Hydrocarbon Derivatives
Estimate ?Hv(298) of 1,2-dichlorobenzene C6H4Cl2
1,2-dichlorobenzene 95-50-1 51.2 (256) 99/
20 (363-454) 44.5 (376) EB 98/8 (256-287) 50.
8 (271) 96/19 (413-453) 50.9 (298) GC 94/22
(258-313) 51.2 GC 94/23 (373-453) 44.0 (388)
A 87/5 (360-450) 49.9 (298) 84/991/2 (301-
343) 50.0 (322) GS 82/1
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Estimate the vaporization enthalpy of
perfluoro-2-methylbutane. Estimate the
vaporization enthalpy of nonafluorocyclopentane E
stimate the vaporization enthalpy of dibutyl
disulfide
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Estimate the vaporization enthalpy of
2-propoxyethanol Estimate the vaporization
enthalpy of 2-isopropoxyethanol Estimate the
vaporization enthalpy of 2,2-dimethoxypropane