Explosives heat of formation

EXPLOSION HEATS OF FORMATION, COMBUSTION, DEFLAGRATION, EXPLOSION AND DETONATION. See Vol 4, pp D369-L to D384-R... 

Attention was paid to the explosive properties of ammonium nitrate as early as 1883 by Berthelot [10] who first formulated the equation of decomposition, and gave the numerical data for the heat of explosion, heat of formation, the volume of gases evolved and the temperature of explosion. 

Hydrides. Zirconium hydride [7704-99-6] in powder form was produced by the reduction of zirconium oxide with calcium hydride in a bomb reactor. However, the workup was hazardous and many fires and explosions occurred when the calcium oxide was dissolved with hydrochloric acid to recover the hydride powder. With the ready availabiHty of zirconium metal via the KroU process, zirconium hydride can be obtained by exothermic absorption of hydrogen by pure zirconium, usually highly porous sponge. The heat of formation is 167.4 J / mol (40 kcal/mol) hydrogen absorbed. 

Dichlorine monoxide is the anhydride of hypochlorous acid the two nonpolar compounds are readily interconvertible in the gas or aqueous phases via the equilibrium CI2 O + H2 0 2H0Cl. Like other chlorine oxides, CI2O has an endothermic heat of formation and is thus thermodynamically unstable with respect to decomposition into chlorine and oxygen. Dichlorine monoxide typifies the chlorine oxides as a highly reactive and explosive compound with strong oxidhing properties. Nevertheless, it can be handled safely with proper precautions. 

Explosions in the Absence of Air Some gases with positive heats of formation can be decomposed explosively in the absence of air. Ethylene reacts explosively at elevatea pressure and acetylene at atmospheric pressure in large-diameter piping. Heats of formation of these materials are -t-52.3 and -t-227 kj/mol (-1-22.5 and -1-97.6 X 10 Btii/lb mol), respec tively. 

Heat of Explosion. 1138.5 keal/kg (w as vapor) Heat of Formation. 78.1kcal/mole Power. 540ml or 92% NG by Trauzl Pb block test with w tamping... 

Explosivity Capacity to liberate heat and gases Structural alerts Heats of formation... 

Fullerenes may be expected to be at least as autoxidisable as charcoal (graphite) when suitably finely divided. Heats of formation (solid, w.r.t. graphite) Ceo 3.2 kJ/g C70 3.0 kJ/g. They have hitherto proved surprisingly stable kinetically [8].The cyclic Cig, when available in substantial quantity, will surely prove capable of spontaneous combustion and will probably be explosive [9],... 

The molar heat of formation of this endothermic compound (+230-250 kJ, 4.5 kJ/g) is comparable with that of buten-3-yne (vinylacety lene). While no explosive decomposition of the isocyanide has been reported, the possibility should be borne in mind [1], It is stable at — 15°C, but isomerises to acrylonitrile and polymerises at ambient temperature [2],... 

As is the case with numerous other metal alkyls, beryllium alkyls are spontaneously flammable in air. Beryllium oxide is produced, and it has a heat of formation of — 611kJ/mol. Dimethylberyllium also reacts explosively with water, and some of its other properties resemble those of trimethylaluminum. This should not be surprising because the metals have a strong diagonal relationship that relates to their similar charge-to-size ratios. 

Many, but not all, endothermic compounds have been involved in violent decompositions, reactions or explosions, and in general, compounds with significantly positive values of standard heat of formation may be considered suspect on stability grounds. Notable exceptions are benzene and toluene (AH°f +82.2, 50.0 kJ/mol 1.04, 0.54 kJ/g, respectively), where there is the resonance stabilising effect of aromaticity. Values of thermodynamic constants for elements and compounds are tabulated conveniently [1], but it should be noted that endothermicity may change to exothermicity with increase in temperature [2], There is a more extended account of the implications of endothermic compounds and energy release in the context of fire and explosion hazards [3], Many examples of endothermic compounds will be found in the groups ... 

For most explosives, where a small volume of a sohd is converted into a large volume of gas, a good approximation of the energy release AG is dominated by the enthalpy change AH AG = AH—TAS, where AH is given by the heat of formation of the products minus the heat of formation of the reactants [see Eqs. (1) and (2)]. Hence, it is desirable that chemical explosives have as positive a heat of formation as possible. 

The heat of explosion is then calculated as the difference between the sum of the heats of formation of the products, and the sum of the heats of formation of the reactants, using the usual thermodynamic convention that heat evolved is negative. 

Octanitrocubane (ONC) has a density of 1.979 g/cm, a calculated heat of formation of 594 kJ/mol, and a decomposition temperature above 200 °C. The explosive performance of octanitrocubane (41) from theoretical calculations is predicted to be exdemely high. The most recent theoretical estimate "" of VOD is 9900 m/s, making this compound one of the most powerful explosives synthesized to date. Surprisingly, the density of heptanitrocubane... 

The heat produced by a chemical reaction is expressed by the heat of explosion , Hexp- Hgxp is determined by the difference between the heat of formahon of the reactants, AHj-r, and the heat of formation of the products, AHj p, as represented by... 

Beal, R. W., and Brill, T. B., Thermal Decomposition of Energetic Materials 78. Vibrational and Heat of Formation Analysis of Furazans by DFT, Propellants, Explosives, Pyrotechnics, Vol. 25, 2000, pp. 247-254. 

This book is divided into four parts. The first part (Chapters 1-3) provides brief reviews of the fundamental aspects relevant to the conversion from chemical energy to aerothermal energy. References listed in each chapter should prove useful to the reader for better understanding of the physical bases of the energy conversion process energy formation, supersonic flow, shock wave, detonation, and defl agration. The second part (Chapter 4) deals with the energetics of chemical compounds used as propellants and explosives, such as heat of formation, heat of explosion, adiabatic flame temperature, and specific impulse. 

Many, but not all, endothermic compounds have been involved in violent decompositions, reactions or explosions, and in general, compounds with significantly positive values of standard heat of formation may be considered suspect on stabihty groimds. Notable exceptions are benzene and toluene -1-82.2, 50.0 kJ/mol ... 

A density functional procedure has been used to compute the gas-phase heat of formation of the triazolooxadiazole 17, and the calculated value of Ai/f° at 202 kcal moP (903 cal is more than 4 times greater than that of a leading military explosive, l,3,5-trinitrohexahydro-l,3,5-triazine (RDX), 18 (206cal g ), which supports the hypothesis that a high energy content is associated with nitrogen catenation <1995JST(358)63>. 

---