Formation, heats tables

Strategy First, calculate AH using heats of formation in Table 8.3. Then calculate AE using Equation 8.6. 

It is possible to calculate a heat of reaction for a high-energy system by assuming what the reaction products will be and then using available thermodynamic tables of heats o/formation. "Heat of formation" is the heat associated with the formation of a chemical compound from its constituent elements. For example, for the reaction... 

Heat of Combustion. See Vol 4, p D369 (Tables D380-1) of Encycl under DETONATION (AND EXPLOSION), DEFLAGRATION (AND COMBUSTION), AND FORMATION, HEATS OF... 

Formation, Heats of, See Vol 4, pp D369 D370 and also in Tables A B, pp D38O D381... 

There is a chemical reaction associated with the problem and that reaction must be written as the starting place for the solution to the problem. We can also place the enthalpy of formation (heat of formation) for the participants in the reaction from Table 7-1, multiplied by the coefficient used in balancing the equation. Recall that for an element in the ground state, the AHj is zero. 

An important aspect of fluorine thermochemistry is the effect of increasing a-fluorine substitution on the C—F bond dissociation energy (BDE). This geminal stabilization is illustrated by the C—F BDE in the fluorinated methanes—the CHF series with associated C—F and C—H BDEs given below (for radical heats of formation used see Table 10, for halon atom heats of formation see Table 8) ... 

Tables 1 and 2 contain the formation heat values for adsorption complexes of sulfur-containing amino acids on a silica surface from gas phase and for their zwitterions with a hydrated environment...

Solution Standard heats of formation from Table 4.4 are... 

The formation heats of conformers A and C of 2-trichloromethyl-5(6)-nitroben-zimidazole (Scheme 3.77) calculated by AMI, MNDO, PM3 methods and 35C1 NQR frequencies computed from the Townes-Dailey equation [1408] (TD) and modification Townes-Dailey equation (3.8) [1409, 1410] (MTD) have been analyzed (Table 3.84) [1407],... 

Table 3.84 The formation heats (H, kcal/mole) of the conformers A and C of 2-trichloromethyl-5(6)-nitrobenzimidazole and 33C1 NQR frequencies (v, MHz), obtained from TD and MTD equations...

Because of the additional calibration, the MM2ERW force field leads to heats of formation of conjugated polyenes or conjugated systems containing the cyclopropyl group in close agreement with experimental heats of formation (see Table 1 in Section II.C). With 1,3-butadiene and vinylcyclopropane as reference compounds, none of these molecules possesses any extra stabilization. This, however, is different for the potentially homocon-jugated molecules listed in Table 2 of Section II.C. 

Key words critically evaluated data enthalpy enthalpy of formation entropy equilibrium constant of formation Gibbs energy function Gibbs energy of formation heat capacity thermochemical tables. 

Table of Standard Affinities of Formation, Heats of Formation and Standard Entropies. 

For many species, thermochemical properties (Gibbs energy and enthalpy of formation, heat capacity) can be found in the NIST Chemistry Webbook [5]. A good written source, especially for small molecules, is the JANAF Tables [30]. The NBS Tables of Chemical Thermodynamic Properties... 

The enthalpies in Tables 2-4 can be used to find AH°(298 K) and AH°(2000 K) for numerous reactions between these atoms and molecules. If solid or liquid boron or aluminum is involved, its heat of sublimation or vaporization at 298 K or 2000 K must be appropriately included. Alternatively, AH°(298 K) can be determined from the heats of formation in Tables... 

This method allows an easier calculation of the reaction energy since it only considers irreversible reactions and leaves out all sensible heat exchanges. The reference temperature for the reactions is 273.16 K. The formation heat is shown in Table 31.29. The total heat of formation is the difference between endothermic and exothermic reactions heat, which is 418.5 kcal/kg cli. 

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