Exothermicity values, calculating

Bromination of methane is exothermic but less exothermic than chlorination The value calculated from bond dissociation energies is AH° = -30 kJ Al though bromination of methane is energetically fa vorable economic considerations cause most of the methyl bromide prepared commercially to be made from methanol by reaction with hydrogen bromide... 

Thus for the photoreduction of benzophenone in the presence of benzhydrol (RH = < 2CHOH, C—H x 78 kcal/mole) the overall reaction is exothermic by 26 kcal/mole. For the photoreduction of acetophenone the value calculated in this way is —31 kcal/mole, while for fluorenone the abstraction is still exothermic by 10 kcal/mole. Clearly, the energetics of the abstraction reaction is not the reason why benzophenone and acetophenone photoreduce but fluorenone does not, since the values for the overall reaction would indicate that all three compounds should react. However, this conclusion is not necessarily valid if large activation energies are involved. ... 

In order to clarify these points and to verify the practicability of our concept, we investigated the course of the overall transformation by density functional theory (DFT) as depicted in Scheme 16. As expected, both the ring opening of 40 to 41 and the 5-exo cyclizations to 42 are exothermic. The calculated Ti - 0 bond lengths (1.86 A) are in excellent agreement with values obtained from crystallographic structures (1.85-1.89 A) [67-69]. 

The value reported in [82WAG/EVA] is -587.0 kJ-moP. The more negative value calculated by Trzil is mainly caused by an earlier accepted value of the enthalpy of formation of Se02(cr), which was about 10 kJ-mol too exothermic. The review adopts ... 

Comment The estimated value based on average bond energies is quite close to the hue value calculated using A//y data. In general, Equation (9.4) works best for reactions that are either quite endothermic or quite exothermic, that is, for A//° > 100 kJ or for LH° < -100 kJ. 

The reaction is moderate exothermic with AHr = -114 kJ/mol. A measure of exothermicity is the adiabatic temperature rise. Table 8.1 gives some values calculated for an inlet temperature of 400 K and 1 atm. The adiabatic temperature rise for the stoichiometric mixture is considerable (441.6 K), but the dilution with benzene in the ratio 5 1 makes drop it to 144.6. If diluted ethylene feedstock is considered, the... 

If a bond is partially covalent, the experimental lattice energy (from Born Haber) will be bigger (more exothermic) than the value calculated from a purely ionic model. 

From the results, it can bo seen that the pressure has a great influence on the enthalpy of reaction. While a value of Ah = —52758 )/mol is calculated for the ideal gas state, a much higher exothermal value of -59790 J/mol is obtained at 600 atm, which is in good agreement with the value 59650 J/mol obtained using the equations of Gillespie and Beatty [4] used in Ullmann [5]. This value is more than... 

Exothermic reactions (i.e., reactions favored to give products) have overall Problems 8.3, 8.17, 8.27 negative values calculated in this way. 

Interaction parameters, Xi2> of all pure biodegradable polymers-solute and some blends-solute systems were calculated using Equation (8). Table III shows the values of Xi2 for selected solutes. Only alkanes and alcohols were used for X23 calculations, other solutes could not be used due to the lack of Antoine constants in the literature. Generally, X12 showed more exothermic values as a number of carbons (n) in both alkane, acetate and alcohol series increased. Dodecane, butyl acetate and butanol showed the most exothermic values among alkanes, acetates and alcohols. Values of X12 become more exothermic as temperature increased as expected. The exothermic values are indicators for the solubility of these polymers in solutes. The dispersive forces among the three Emilies played a major role in determining the solubility. 

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