Decomposition reaction, high

To detect tlie initial apparent non-RRKM decay, one has to monitor the reaction at short times. This can be perfomied by studying the unimolecular decomposition at high pressures, where collisional stabilization competes with the rate of IVR. The first successful detection of apparent non-RRKM behaviour was accomplished by Rabinovitch and co-workers [115], who used chemical activation to prepare vibrationally excited hexafluorobicyclopropyl-d2 ... 

If the speed with which ethylene is passing through a tube is comparable to the speed with which the decomposition reaction travels through the ethylene, then one or other of the fronts where the decomposition is occurring will be stationary relative to the tube. Under these conditions the tube will be heated to a very high temperature rapidly and fail at a pressure much lower than the burst pressure of the tube at ambient temperature. 

Direct, One-Step Thermal Water Splitting. The water decomposition reaction has a very positive free energy change, and therefore the equihbrium for the reaction is highly unfavorable for hydrogen production. 

Some of the composition adjustments in the Alnicos result in a high Curie temperature so that the decomposition reaction can take place relatively rapidly below This is particularly tme for Co, which is 24 wt % or greater for the anisotropic magnets. Another important consideration is the suppression of nonmagnetic fee y-phase which may appear at 1000—1100°C in this regard, the amount of Al, which is a y-suppressor, is critical. The formation of y is pronounced if the Al content falls much below 7—8 wt %. 

As early as 1923 Hinshelwood and Topley (27) noted the exceptionally erratic behavior of palladium foil catalyst in the formic acid decomposition reaction within 140-200°C. The initially very high catalytic activity decreased 102 times during the exposure of palladium to hydrogen, which is a product of the reaction. Though the interpretation does not concern the /3-hydride formation, the authors observation deserves mentioning. 

The solutions obtained by Rosen show that at low pressures, the burning rate becomes linear in pressure and the surface pyrolysis characteristics are not important. At high pressures, however, the burning rate becomes independent of pressure and is determined almost entirely by the decomposition reactions at the solid surface. Rosen points out that this simple model can... 

The high values of E generally characteristic of the decomposition reactions of metal oxyhalides are widely interpreted as evidence that the initial step in anion breakdown is the rupture of the X—O bond and that the energy barrier to this reaction is not very sensitive to the properties of the cation present. Information of use in the formulation of reaction mechanisms has been obtained from radiolytic studies of oxyhalogen salts [887-889],... 

Still, a question arises as to why the high concentration of oxygen in the atmosphere does not react with the large amounts of reduced substances present. After all, the reaction between oxygen and fixed carbon is very exer-gonic AG for the decomposition reaction above is about —480 kj per mole of fixed carbon. 

Irradiation of cyclo-S% dissolved in CS2 by a high-pressure mercury lamp at 20 °C produces the homocycles S7, S, S12, S9, Sio, and probably S5 in concentrations decreasing in this order. Irradiation of Se in CS2 gives mainly Ss and S7 while irradiation of S7 generates Ss and S. Similarly, photolysis of S12 in CS2 yields Ss, S7, and Se [51]. For these reasons UV-Vis spectra of compounds containing S-S bonds must be recorded with caution not to trigger decomposition reactions. 

Since hydrogen sulfide and elemental sulfur occur together in hot underground deposits of natural gas (so-called sour gas ) the formation of sulfur-rich polysulfanes under these high-pressure conditions is very likely. If the gas is produced and in this context the pressure and temperature lowered, the decomposition reaction (Eq. 1) takes place and the precipitated sol-... 

Fig. 5.6 (Left) Comparison of band energy levels for different II-VI compounds. Note the high-energy levels of ZnSe. Representation is made here for electrodes in contact with 1 M HQO4. The reference is a saturated mercury-mercurous sulfate electrode, denoted as esm (0 V/esm = +0.65 V vs. SHE). (Right) Anodic and cathodic decomposition reactions for ZnSe at their respective potentials (fidp, Fdn) and water redox levels in the electrolytic medium of pH 0. (Adapted from [121])...

Catalysts include oxides, mixed oxides (perovskites) and zeolites [3]. The latter, transition metal ion-exchanged systems, have been shown to exhibit high activities for the decomposition reaction [4-9]. Most studies deal with Fe-zeolites [5-8,10,11], but also Co- and Cu-systems exhibit high activities [4,5]. Especially ZSM-5 catalysts are quite active [3]. Detailed kinetic studies, and those accounting for the influence of other components that may be present, like O2, H2O, NO and SO2, have hardly been reported. For Fe-zeolites mainly a first order in N2O and a zero order in O2 is reported [7,8], although also a positive influence of O2 has been found [11]. Mechanistic studies mainly concern Fe-systems, too [5,7,8,10]. Generally, the reaction can be described by an oxidation of active sites, followed by a removal of the deposited oxygen, either by N2O itself or by recombination, eqs. (2)-(4). 

As well as the normal addition reaction, an extremely exothermic decomposition reaction may occur, particularly at high vessel loadings. At loadings of 0.8 ml of 1 1 mixture per ml, the violent reaction, catalysed by iron(III) chloride, initiates at —40°C and will attain pressures above 0.7 kbar at the rate of 14 kbar/s. At 0.5 ml loading density, a maximum pressure of 68 bar, attained at 114 bar/s, was observed. 

A self sustaining decomposition reaction propagating faster than the speed of sound by means of a shock wave (the characteristic property of high as opposed to low explosives). 

A thermal decomposition reaction is a reaction that is activated by heat or high temperatures and that generates simpler (i.e., containing fewer atoms and thus characterized by lower molecular weights) substances from a single complex substance. The overall balanced equation for the thermal decomposition of sodium bicarbonate reveals the simpler substances produced ... 

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