Heat of combustion formation

See alphabetical index for heats of combustion, formation, vaporization, etc) 49b) N.A. Lange et al, "Handbook of Chemistry , Sandusky, Ohio(1968) (See alphabetical index under heats of combustion, formation, vaporization, etc) 50) C.G. Dunkle, private communication, Jan I968 Note International Critical Tables, Landolt-Bornstein Tables, US Bureau of Mines Publications and Picatinny Arsenal Reports on heats of combustion, heats of formation, etc are listed under Addnl Refs, which follow... 

Table 4-10. Heats of Combustion, Formation, Nitration, and Crystaluzation Benzene Series and Lower Paraffins...

Heats of combustion, formation and hydrogenation of some aromatic hydrocarbons which are stericaUy-hindered... 

THE HEATS OF COMBUSTION, FORMATION, AND ISOMERIZATION OF ISOMERIC MONOGLYCERIDES. 

Standard heats of combustion, formation, and sublimation and strain energies are reported for nortricyclene and norbornene. The enthalpies of isomerization of... 

Pepekin s study of the thermodynamic properties of difluoramino and nitro compounds [74,75] included many organic difluoramines besides the products of electrophilic difluoramination cited above. Properties reported include heats of combustion, formation, and atomization, Clausius-Clapeyron equation parameters, and the enthalpies and entropies of evaporation and sublimation. This collection of properties allowed estimation of group additivity parameters for general calculations of thermodynamic properties of organic difluoramines, which were compared to those of corresponding nitro groups. 

Equations (1) and (2) are the heats of formation of carbon dioxide and water respectively Equation (3) is the reverse of the combustion of methane and so the heat of reaction is equal to the heat of combustion but opposite in sign The molar heat of formation of a substance is the enthalpy change for formation of one mole of the substance from the elements For methane AH = —75 kJ/mol... 

The heats of formation of most organic com pounds are derived from heats of reaction by arith metic manipulations similar to that shown Chemists find a table of AH values to be convenient because it replaces many separate tables of AH° values for indi vidual reaction types and permits AH° to be calcu lated for any reaction real or imaginary for which the heats of formation of reactants and products are available It is more appropriate for our purposes however to connect thermochemical data to chemi cal processes as directly as possible and therefore we will cite heats of particular reactions such as heats of combustion and heats of hydrogenation rather than heats of formation... 

You have seen that measurements of heats of reaction such as heats of combustion can pro vide quantitative information concerning the relative stability of constitutional isomers (Section 2 18) and stereoisomers (Section 3 11) The box in Section 2 18 described how heats of reaction can be manipulated arithmetically to generate heats of formation (AH ) for many molecules The following material shows how two different sources of thermo chemical information heats of formation and bond dissociation energies (see Table 4 3) can reveal whether a particular reaction is exothermic or en dothermic and by how much... 

A particularly useful property of the PX monomer is its enthalpy of formation. Conventional means of obtaining this value, such as through its heat of combustion, are, of course, excluded by its reactivity. An experimental attempt was made to obtain this measure of chemical reactivity with the help of ion cyclotron resonance a value of 209 17 kJ/mol (50 4 kcal/mol) was obtained (10). Unfortunately, the technique suffers from lack of resolution in addition to experimental imprecision. It is perhaps better to rely on molecular orbital calculations for the formation enthalpy. Using a semiempirical molecular orbital technique, which is tuned to give good values for heat of formation on experimentally accessible compounds, the heat of formation of /5-xylylene has been computed to be 234.8 kj/mol (56.1 kcal/mol) (11). 

The stmcture of DPXN was determined in 1953 from x-ray diffraction studies (22). There is considerable strain energy in the buckled aromatic rings and distorted bond angles. The strain has been experimentally quantified at 130 kj/mol (31 kcal/mol) by careful determination of the formation enthalpy through heat of combustion measurements (23). The release of this strain energy is doubtiess the principal reason for success in the particularly convenient preparation of monomer in the parylene process. 

Table 3. Heats of Combustion and Formation for Metal Carbonyls...

Molecular formular Heat of combustion, kj / mof Reference Heat of formation, kJ / mof Reference... 

Acid Heat of formation, kl / mol Flash point, °C Heat of combustion, kl / mof... 

Compound Heat of combustion (crystalf Heat of combustion (sasT - (Heat of atomization) exp - (Heat of Heat of atomization) formation calc expf Heat of formation calc. ... 

The initial cloud fraction used to form soot (1 - /<.) can be estimated as the ratio of heat of formation to heat of combustion (Lihou and Maund 1982). 

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