And enthalpy of vaporization

Selected physical properties are given in Table 1 and some thermodynamic properties in Table 2. Vapor pressure (P) and enthalpy of vaporization (H) over the temperature range 178.45 to 508.2 K can be calculated with an error of less than 3% from the following equations wherein the units are P, kPa Pi, mj/ mol T, K and = reduced temperature, T/ T (1) ... 

Alkanes with long, unbranched chains tend to have higher melting points, boiling points, and enthalpies of vaporization than those of their branched isomers. The difference arises because, compared with unbranched molecules, the atoms of neighboring branched molecules cannot get as close together (Fig. 18.5). As a result, molecules with branched chains have weaker intermolecular forces than their unbranched isomers. 

Osborn, A.G., Scott, D.W. (1978) Vapor-pressure and enthalpy of vaporization of indan and five methyl-substituted indans. J. Chem. Thermdyn. 10, 619-628. 

Malaspina, L., Bardi, G., Gigli, R. (1974) Simultaneous determination by Knudsen-effusion microcalorimetric technique of the vapor pressure and enthalpy of vaporization of pyrene and 1,3,5-triphenylbenzene. J. Chem. Thermodyn. 6, 1053-1064. 

Verevkin, S.P. (2003) Vapor pressures and enthalpies of vaporization of a series of 1- and 2-halogenated naphthalene. J. Chem. Thermodyn. 35, 1237-1251. 

Ashcroft, S.J. Vapor pressmes and enthalpies of vaporization of benzyl halides, J. Chem. Eng. Data, 21(4) 397-398, 1976. 

Kramer, C-R., Henze, U. (1990) Verteilungseigenschaften von Bensenderivaten. 1. Zum temperatureinfluss auf die verteilung von monosubstituierten benzenen und nitrobenzenen im system w-octanol/wasser. Z. Phys. Chemie—Leizing 271, 503-513. Krasnykh, E.L., Vasiltsova, T.V., Verevkin, S.P., Heintz, A. (2002) Vapor pressures and enthalpies of vaporization of benzyl halides and benzyl ethers. J. Chem. Eng. Data 47, 1372-1378. 

The last term in the formula (1-196) describes electrostatic and Van der Waals interactions between atoms. In the Amber force field the Van der Waals interactions are approximated by the Lennard-Jones potential with appropriate Atj and force field parameters parametrized for monoatomic systems, i.e. i = j. Mixing rules are applied to obtain parameters for pairs of different atom types. Cornell et al.300 determined the parameters of various Lenard-Jones potentials by extensive Monte Carlo simulations for a number of simple liquids containing all necessary atom types in order to reproduce densities and enthalpies of vaporization of these liquids. Finally, the energy of electrostatic interactions between non-bonded atoms is calculated using a simple classical Coulomb potential with the partial atomic charges qt and q, obtained, e.g. by fitting them to reproduce the electrostatic potential around the molecule. 

The water adsorbed on the surface is described by the SPC model [16]. This fast computable model is well suited for very large systems, as it reproduces quite well the thermodynamical properties around ambient temperature, like vapor pressure (0.044 bar against 0.035 bar experimentaly) and enthalpy of vaporization [17]. The extended SPC/E model [18] is not adapted to study adsorption properties since the polarization correction that it introduces cannot be well defined in the highly inhomogeneous environment of a molecule adsorbed on a surface. Furthermore, the predicted vapor pressure is only half the experimental value [19]. 

The boiling point and enthalpy of vaporization are calculated from the cross over point of the BeClg U) and (g) tables. The analysis of the liquid vapor pressure data is given on the table for BeClgCg). 

These values were based on the heat capacity and enthalpy of vaporization measurements of Hlldenbrand et... 

The adopted boiling temperature (at 10 bar) and enthalpy of vaporization are taken from the equation of state formulation of Haar et al. ( ). 

The normal boiling point and enthalpy of vaporization are those calculated for the ideal gas from these tables. The boiling point found for the real gas (387.3 K) by Hieber and Woerner (5) is in good agreement. The selected enthalpy of vaporization, aH (298.15 K) = 10.69 kcal mol, Is based on the vapor pressure data of Scott et al., ( ), series III. Vapor pressure measurements of Hieber and Woerner (5), are in satisfactory agreement as shown below. 

The strong bonds formed by fluorine make many of its compounds relatively inert. Fluorine s ability to form hydrogen bonds results in relatively high melting points, boiling points, and enthalpies of vaporization for many of its compounds. 

Trends in boiling points, melting points and enthalpies of vaporization for p-block binary hydrides... 

The references provide additional information on water activity, osmotic coefficient, and enthalpy of vaporization. 

The heat of hydrogenation by Flitcroft and Skinner was - 293.51 kJ mol They used ethanol as the calorimeter fluid. After correction for the enthalpy of solution of ethylbenzene in ethanol, they found i/h = - 296.02 4.19 kJ mol for the pure liquid to liquid hydrogenation . The authors suggested that a catalyst interaction and enthalpies of vaporization are included in the earlier values, making them more exothermic than they should be by about 20.93 kJ mol which seems to be very probable. 

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