Temperature, absolute explosion

Another theoretical value introduced by Berthelot is the force specifique (called by Sarrau force de I explosif), This, designated as f, is obtained from the expression 1073V T/273, where V0 is the specific vol and T is the calcd absolute temperature of explosion... 

Moisture measurements are important in the process industries because moisture can foul products, poison reactions, damage equipment, or cause explosions. Moisture measurements include both absolute-moisture methods and relative-humidity methods. The absolute methods are those that provide a primaiy output that can be directly calibrated in terms of dew-point temperature, molar concentration, or weight concentration. Loss of weight on heating is the most familiar of these methods. The relative-humidity methods are those that provide a primaiy output that can be more direc tly calibrated in terms of percentage of saturation of moisture. 

Sodium azide [26628-22-8] M 65.0, m 300°(dec, explosive), pK 4.72 (for HN3). Crystd from hot water or from water by the addition of absolute EtOH or acetone. Also purified by repeated crystn from an aqueous solution saturated at 90° by cooling it to 10°, and adding an equal volume of EtOH. The crystals were washed with acetone and the azide dried at room temperature under vacuum for several hours in an... 

The behavior of liquid flow in micro-tubes and channels depends not only on the absolute value of the viscosity but also on its dependence on temperature. The nonlinear character of this dependence is a source of an important phenomenon - hydrodynamic thermal explosion, which is a sharp change of flow parameters at small temperature disturbances due to viscous dissipation. This is accompanied by radical changes of flow characteristics. Bastanjian et al. (1965) showed that under certain conditions the steady-state flow cannot exist, and an oscillatory regime begins. 

The presence of HMX as an impurity in RDX is not a problem when the product is used as an explosive. However, the need for an analytical sample of RDX makes other more indirect methods feasible. One such method involves the oxidation of 1,3,5-trinitroso-1,3,5-triazacyclohexane (109) ( R-salt ) with a mixture of hydrogen peroxide in nitric acid at subambient temperature and yields analytical pure RDX (74%) free from HMX." The same conversion has been reported in 32 % yield with three equivalents of a 25 % solution of dinitrogen pentoxide in absolute nitric acid. l,3,5-Trinitroso-l,3,5-triazacyclohexane (109) is conveniently prepared from the reaction of hexamine with nitrous acid at high acidity. ... 

However, the complete reaction mechanism of the hydrogen oxidation reaction is much more complex, both in its number of reaction steps, number of intermediates (OOH and H2O2), and observed behavior. A mixture of H2 and O2 can sit in a diy bulb for many years with absolutely no H2O detected. However, if water is initially present, the reaction will begin, and if a spark is ignited or a grain of platinum is added to the mixture at room temperature, the reaction wiU occur instandy and explosively. 

As each individual molecule of explosive undergoes ordinary thermal reaction starting with a low initial temperature, there is a lag effect or induction period that depends exponentially on the reciprocal of the initial absolute temperature. 

Activation Energy It is experimentally seen that the explosion delay (ED) for the build-up of an explosion decreases with an increase in temperature. Therefore, energy of activation (IQ can be calculated on the basis of a relationship between the experimentally obtained ED and the absolute temperature of the Wood s metal bath. This relationship is expressed by an Arrhenius type of equation, that is, (Equation 3.3) ... 

T = absolute temperature of the Wood s metal bath A = frequency factor depending on the explosive. 

Follow the procedure described in Method 101.5 for the determination of the percentage moisture and volatile in the explosive. However, in this determination heat for 6 hours in a vacuum oven at a temperature of 55° 2°C. and a pressure (absolute) of 80mm 10mm of mercury instead of four (4) hours in an oven at 100° 5°C. and atmospheric pressure. 

Pressure-Temperature Explosion Limit for Mixtures of Constant Compositior. Consider a gaseous, homogeneous, simple ordered, exothermic reaction occurring in a closed vessel. The vessel is assumed to be immersed in a furnace so that the vessel walls always remain at the furnace temperature T0. For the reaction mA + nB —> products, with an overall reaction order N = m + n, the reaction rate, r, is given by r = kCAmCBn, where Ca and Cb, are concentrations of the reactants, A and B. The specific rate constant, k, is assumed to obey the simple Arrhenius relation, k = Cc EIRT, where C, the pre-exponential factor, is independent of the absolute temperature, T R is the molar gas constant and E is the energy of activation. The initial reactant concentrations, (Ca)0 and (CB)a, are given in terms of P, the initial total pressure XQ, the initial mole fraction of A, and T0, the initial temperature of the reactant mixture, as follows ... 

Owing to the highly explosive nature of the diazobenzene nitrate, its preparation should never be undertaken except the compound is wanted for research or some special purpose. 20 gms. of aniline are placed in a beaker, well cooled, and boiled-out nitric acid, previously diluted with half its volume of water, oarefully added till the mixture sets to a thick crystalline paste—aniline nitrate. The crystalline mass is filtered off at the pump, and washed with a little cold water. 5 gms. of the moist salt are finely powdered and placed in a small flask with enough water just to cover the substance. The flask is now well cooled in ice-water, and nitrous fumes (for preparation, see p. 513) are led in with frequent agitation until all the aniline nitrate has disappeared. At no time must the temperature of the flask rise above 10°. Should there not be sufficient water to keep all the diazobenzene nitrate formed in solution, its crystalline form will easily enable it to be distinguished from the aniline salt. When the reaction is finished the contents of the flask are poured into 3 times their volume of absolute alcohol, and ether is added to this mixture as long as crystals separate. If too much water has been added to the aniline nitrate from the beginning, a thick aqueous solution of diazobenzene nitrate separates out in place of the crystals. If this occurs, the ether-alcohol is decanted off, and the residue redissolved in absolute alcohol, and reprecipitated with ether. On no account must... 

As appears from the formula one can find D from an experiment on an explosion at a very high temperature by measuring the nitric oxide yield in the products and the cooling rate without a knowledge of the temperature reached during the explosion. Due to the complicated temperature distribution in the reaction products (Mache effect, cf. 5) this method of computing D and the absolute value of the rate coefficient is extremely useful and has been used by us (see 10). 

Temperature Upon Initiation Times of Four Primary Explosives , NOLTR 72-123 (1972) [Leopold reports that when the induction time to hot wire ignition is compared between Ag Azide, LA, n-L Styphnate and basic L Styphnate at temps ranging from 550° to 3400°, the latter two always have the longest initiation times. Also, that pulsed hot wire initiation of both n-L Styphnate and basic L Styphnate gives a linear relationship between the log of the induction time and the reciprocal of the absolute temp (Arrhenius relationship)]... 

Most chemical reactions give off heat and are classified as exothermic reactions. The rate of a reaction may be calculated by the Arrhenius equation, which contains absolute temperature, K, equal to the Celsius temperature plus 273, in an exponential term. As a general rule, the speed of a reaction doubles for each 10°C increase in temperature. Reaction rates are important in fires or explosions involving hazardous chemicals. A remarkable aspect of biochemical reactions is that they occur rapidly at very mild conditions, typically at body temperature in humans (see Chapter 3). For example, industrial fixation of atmospheric elemental nitrogen to produce chemically bound nitrogen in ammonia requires very high temperatures and pressures, whereas Rhizobium bacteria accomplish the same thing under ambient conditions. 

When an explosive slowly decomposes, the products may not follow the previously described hierarchy or be at the maximum oxidation states. The nitro, nitrate, nitramines, acids, etc., in an explosive molecule can break down slowly. This is due to low-temperature kinetics as well as the influence of light, infrared, and ultraviolet radiation, and any other mechanism that feeds energy into the molecule. Upon decomposition, products such as NO, NO2, H2O, N2, acids, aldehydes, ketones, etc., are formed. Large radicals of the parent explosive molecule are left, and these react with their neighbors. As long as the explosive is at a temperature above absolute zero, decomposition occurs. At lower temperatures the rate of decomposition is infinitesimally small. As the temperature increases, the decomposition rate increases. Although we do not always, and in fact seldom do, know the exact chemical mechanism, we do know that most explosives, in the use range of temperatures, decompose with a zero-order reaction rate. This means that the rate of decomposition is usually independent of... 

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