Thermodynamics ideal gases

In this section we summarize some leading thermodynamic properties of the fictitious ideal gas system, with defining characteristics 

Some aspects of the kinetic molecular theory (KMT) of ideal gases were outlined in Sidebar 2.7. The simplest form of KMT refers to monatomic ideal gases, for which the internal energy U and enthalpy H=U + PV = U + nRT can be written explicitly as 

The expressions in (3.72) and (3.73) are valid only for monatomic ideal gases such as He or Ar, and must be replaced by somewhat different expressions for diatomic or polyatomic molecules (Sidebar 3.8). However, the classical expressions for polyatomic heat capacity exhibit serious errors (except at high temperatures) due to the important effects of quantum mechanics. (The failure of classical mechanics to describe the heat capacities of polyatomic species motivated Einstein s pioneering application of Planck s quantum theory to molecular vibrational phenomena.) For present purposes, we may envision taking more accurate heat capacity data from experiment [e.g., in equations such as (3.84a)] if polyatomic species are to be considered. The term perfect gas is sometimes employed to distinguish the monatomic case [for which (3.72), (3.73) are satisfactory] from more general polyatomic ideal gases with Cv nR. 

SIDEBAR 3.8 CLASSICAL THEORY OF MONATOMIC AND POLYATOMIC IDEAL GASES 

Only for the monatomic case (N = 1) is the classical equipartition estimate qualitatively reasonable. 

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This semi-empirical method is recommended as a convenient and economic alternative to determine ideal gas thermodynamic properties of oxygenated heterocycles. 

Burcat and McBride 1995 Ideal Gas Thermodynamic Data for Combustion and Air-Pollution Use [52] see also [51]. 

Curran et ah The Ideal Gas Thermodynamics of Diesel Fuel Ingredients. I. Naphthalene Derivatives and their Radicals [80]... 

A. Burcat. Ideal Gas Thermodynamic Data in Polynomial Form for Combustion and Air Pollution Use. http //garfield.chem.elte.hu/Burcat/burcat.html or ftp //-ftp.technion.ac.il/pub/supported/aetdd/thermodynamics, 2002. 

H. Curran, C. Wu, N. Marinov, W.J. Pitz, C.K. Westbrook, and A. Burcat. The Ideal Gas Thermodynamics of Diesel Fuel Ingredients. I. Naphthalene Derivatives and Their Radicals. J. Phys. Chem. Ref. Data, 29 463-517,2000. 

The molecular parameters for C60H2n can be obtained by the methods of quantum chemistry. The energy of molecules as well as the formation enthalpy is a function of composition and structure of molecules. So, the sequence of computational procedures for calculation of the ideal-gas thermodynamic properties can be presented as the following schemes (Figs. 4.7 and 4.8). 

A report on the ideal gas thermodynamic properties of sulfur heterocyclic compounds lists data on tetrahydrothio-pyran and 5,6-dihydrothiopyran <1995MI1351>. 

Answer Using the ideal gas thermodynamic properties the compression details were calculated and are summarized in the two tables below. 

M. Kami, I. Oref, and A. Burcat, Ab Initio Calculations and Ideal Gas Thermodynamic Punctions of Cyclopentadiene and Cyclopentadiene Derivatives, Journal of Physics Chemical Reference Data, Vol.20, 1991, pp.665-683. 

Metals. Kruglikh, et al. (104) measured saturated vapor pressures of erbium, samarium, and ytterbium by the Knudsen effusion method, and standard (average) sublimation entropies of 18.4, 20.7, and 25.6 cal./(gram atom °K.) were derived. Nesmeyanov, et al. (146) studied the vapor pressure of yttrium by an integral variant of the effusion technique. Similar studies at higher temperatures by Herrick (70) on samarium metal have been interpreted in good accord by both first and second law methods. Ideal gas thermodynamic functions have been derived from 100 °K. to 6000°K. at 100° intervals for both actinide and lanthanide elements by Feber and Herrick (45). 

Rigid rotor - harmonic oscillator - ideal gas thermodynamic characteristics... 

The extent of thermal dissociation of phosgene at 0.5, 1.0 and 10 bar pressure (0.05, 0.1 and 1 MPa, respectively) has been calculated [1764] based on the accepted ideal gas thermodynamic values [359aa], and is illustrated in Fig. 5.3, whilst the enthalpy of formation for this reaction has been based on actual measurements of the equilibrium constant in the temperature range of 645-725 K by heating together carbon monoxide and dichlorine [218], see Section 6.1. The equilibrium reaction depicted in Equation (5.1) has been measured experimentally both by dissociation of phosgene and by association of carbon monoxide and dichlorine [216]. At 603, 553 and 503 C, the dissociation was found to be 91, 80 and 67%, respectively, in reasonable agreement with the values based on the ideal gas calculations illustrated in Fig. 5.3. At temperatures above 800 C, the dissociation is essentially complete [216]. 

Quantum chemical calculations have long been used in the chemical process industry as a method of computing ideal gas thermodynamic and spectroscopic properties, analyzing reaction pathways, and the calculation of heats of formation and related properties. However, it is only recently, as a result of improvements in computational hardware and software, that accurate interaction energies can be computed that can be used directly or combined with molecular simulation to predict the thermodynamic properties of nonideal systems of interest in the practice of chemical engineering. It is this application of quantum chemical calculations that is reviewed in this chapter. 

The ideal gas thermodynamic properties of 1,3-dithiane <95MI 608-03) and 1,3-dioxane <92MI 608-... 

Brechignaz, C., Cahuzac, P. et al., AlP Conf. Proc., Vol. 561,184-195, 2001. Broadus, K. M. and Kass, S. R., /. Am. Chem. Soc., 123, 4189-4196, 2001. Burcat, A., Ideal Gas Thermodynamic Data in Polynomial Form for Combustion and Air-Pollution Use, ftp //ftp.technion.ac.il/pub/supported/aetdd/ther-modynamics, or http //garfield.chem.elte.hu/Burcat/burcat.html, updated on May 2005. 

Feber, R. C., Herrick, C. C., Ideal gas thermodynamic fimctions of lanthanide and actinide elements, Los Alamos Scientific Laboratory, Report LA-3184, (1965), 37 pp.. Cited on page 91. 

Finally, for C-J temperatures above the boiling point of the metal, consideration should be given to the possible existence of distinct species in the gas phase. To include them as components in the assumed set of detonation gases requires knowledge of their molecular geometry and ideal-gas thermodynamic properties (e.g., heat capacity as a function of temperature and heat and entropy of formation). In the absence of such data, it is possible to predict the molecular geometry and thermodynamic properties via quantum-chemical and statistical-thermodynamic calculations, respectively, or to estimate them by analogy with known related molecules. 

Ideal gas thermodynamic properties (ATT/293, 3 °298 and Cp(T), 300 < T (K) < 1500) of 34 cyclic oxygenated hydrocarbons (including 1,2,3-, 1,2,4-, and 1,3,5-trioxane, and 1,2,3- and 1,2,4-trioxene) have been calculated using the PM3 method <1997PCA2471>. Particular correlations of theoretical versus experimental properties were obtained and... 

Table 9 Ideal gas thermodynamic properties for 1,3,5-trloxane and 1,3,5-trlthlane at 1 bar and 298.15 K <1992MI121, 1995MI1351>...

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