Pressure of gaseous product

Theoretical Consideration The decomposition temperature is an important, if not the most important kinetic parameter used in studies of the decomposition processes. It defines the upper limit of reactant stability and the onset of a decomposition reaction. However, temperature is most commonly used only as an additional factor in determination of the Arrhenius parameters. (For instance, Galwey [1] used an average decomposition temperature in his estimations of A values basing on E parameters, known for various substances.) No quantitative definition of the concept of an initial decomposition temperature has been developed, based on a certain specified value of the decomposition rate J, or on parameters related to it (the rate constant k, or the equilibrium pressure of gaseous products Pb)- The detailed interrelation between the decomposition temperature and the molar enthalpy,... 

Parameters marked by one or two primes are those for low and high temperature, respectively. Parameters marked by a subscript expt are the initial (experimental) values of the kinetic parameters. The magnitudes of P(Tt) and P(Tg) correspond to the equilibrium pressure of gaseous product for the corresponding temperatures (water vapour for magnesium hydroxide decomposition). 

Invariance of the E parameter under pressure of gaseous products in the isobaric mode of decomposition Quantitative 5.5... 

D) Miscellaneous. It should be noted that if a reaction between the atmosphere and a thermocouple and the sample container, gas pipe or other parts of the apparatus occurs, damage to the apparatus will be caused. In addition, the effects of the partial pressure of gaseous products (especially water vapor), thermal conductivity, etc., should be monitored carefully. 

The UCKR.ON test problem assumes the simplest uniform surface implicitly, because adsorbed hydrogen coverage is directly proportional to the partial pressure of gaseous hydrogen and adversely affected by the partial pressure of the final products. Such a simple mechanism still amounts to a complex and unaccustomed rate expression of the type solved by second order algebraic equations. 

Many kinetic data can be collected from ARC experiments the exothermic onset temperature, the rate of temperature rise, the rate of pressure rise, and the apparent activation energy. The basic data obtained are, however, thermodynamic properties the adiabatic temperature rise, the maximum pressure potential, the quantity of gaseous products generated, and the heat of reaction can be obtained in one run. The heat of reaction is estimated from ... 

In experiments which are carried out under normal pressure, the gaseous products are taken from a modified, commercially available low temperature furnace. The gas flows viscously in the specially designed capillary through an intermediate volume to the peristaltic pump. Hereby the gas pressure in the intermediate volume is reduced to approx. 1 mm Hg. By means of a variable... 

When 2 moi of N2O5 gas decompose, they form 5 moi of gaseous products. Therefore, the pressure of the system increases as the reaction proceeds, provided that the reaction is carried out in a closed container. Chemists use a pressure sensor to monitor pressure changes. 

At standard temperature and pressure (STP) one mole of an ideal gas occupies a volume of 22.4 dm. Therefore, if the number of moles of gaseous products originating from the gunpowder charge is calculated, an estimate can be made of the closed vessel pressure. 

In order to study sub-detonation reactions and at the same time to take advantage of the available calibration information, the standardized test is modified as shown in Fig 8 reproduced from NOLTR 64-53 (Ref 59). Although this test retains the standardized donor/gap system, its acceptor is unconfined and much shorter. Chemical reaction is desurveillance of the acceptor. Burning is evidenced by the break-out of gaseous products. The curve for time of break-out (time of shock arrival at free surface to time gas is observed) can be extrapolated to give the critical pressures just to initiate the burning... 

Experimental procedures for determination of gaseous products of expls on exploding, by means of Bichel Pressure Gage and Crawshaw-Jones Apparatus are described in Ref 1, but no compns of gases are given Refs 1) Ch.E. Munroe J.E. Tiffany, "Physical Testing of Explosives", USBur-Mines Bull 346(1931), 91-99 2) A. Stett-... 

A low explosion temperature together with a great amount of gaseous products and a high specific pressure suggested the used of ammonium azide as a propellent explosive. In practice the use of the substance, however, is prevented by its high volatility. 

Chlorate explosives yield only a small amount of gaseous products since the major product of explosion is potassium chloride. The specific pressure / is therefore relatively low (the high temperatures do not compensate for the small volume of gases), hence the lead block expansion is low, but Cheddites without nitro compounds—type O No. 6 and S—give an even smaller lead block expansion 180-200 cm3. Some chlorate explosives, when detonated in the open, do not transmit detonation from cartridge to cartridge, differing in this respect from dynamites and ammonium nitrate explosives. In a confined space, however, they behave differently. Here the... 

The volume of gas produced during an explosion will provide information on the amount of work done by the explosive. In order to measure the volume of gas generated standard conditions must be established, because the volume of gas will vary according to the temperature at which the measurement is taken. These standard conditions also enable comparisons to be made between one explosive and another. The standard conditions set the temperature at 0 °C or 273 K, and the pressure at 1 atm. These conditions are known as standard, temperature and pressure , stp . Under these standard conditions one mole of gas will occupy 22.4 dm3, which is known as the molar gas volume. The volume of gas V produced from an explosive during detonation can be calculated from its equation of decomposition, where information can be obtained on the amount of gaseous products liberated. Examples for the calculation of V during detonation of RDX and TNT are given below. 

If there are more moles of gaseous products than gaseous reactants in the balanced chemical equation, then the extra gaseous moles will expand against the atmospheric pressure and the work energy required for this will come at the expense of some of the heat that is liberated. A smaller amount of heat will be liberated than if the reaction had occurred at constant volume. 

CA 33, 3589 (1939) (Description of a special method for analysis of gaseous products evolved on decompn or expln) I)W.E.Gamer, Chim Ind (Paris) 45, Suppl to No 3, pp 111-18 (1941) (Thermal decompn of solid expls and resulting expins) JJH.Muraour J.Basset, Chim Ind 45, Suppl to No 3, pp 218-24 (1941) (Influence of high pressure on the progress, of decompn of expls, particularly in initiating expls) K)Yu.N.Riabinin, ZhFizKhim 20,... 

TPR of the samples in flowing He or H2 were performed in a Pyrex flow system which was also used for catalytic reactions. Acid properties of the samples were probed by TPD of NH3 preadsorbed at RT. The analysis of gaseous products was made by an on-line mass spectrometer or a thermal conductivity detector. Reactions of n-hexane in the presence of excess H2 were carried out at 623 K and atmospheric pressure. A saturator immersed in a constant temperature bath at 273 K was used to produce a reacting mixture of 6% n-hexane in H2. Reaction products were analyzed by an online gas chromatograph (HP-5890A) equipped with a flame ionization detector and an AT-1 (Alltech) capillary column. 

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