Rate of the exothermic

Zr particles react violently with BaCr04 particles, similarly to the burning of Zr particles in air. However, a mixture of Zr particles and BaCr04 particles is relatively insensitive to friction or mechanical shock. DTA and TG data indicate that an exothermic reaction accompanied by a small mass loss occurs at 542 K. The maximum exothermic peak is at 623 K and the rate of the exothermic reaction-gradually decreases as the temperature is increased further. The observed characteristics are highly dependent on the size of the Zr particles because the reaction occurs at their surface. The exothermic peak observed at 623 K becomes higher... 

Water content influences Slurry strength. Dupont Trade literature claims that each % of w removed increases strength by about as much as the addition of 1% of Al. Cook (Ref 9, p215) also shows that increase in w content reduces strength. However, according to Cook, this effect disappears in highly aluminized Slurries As pointed out by Cook (Ref 9, pp 207-10), reaction rate of the exothermic reactions which... 

Incidentally, the effect of the concentration of a chemical of the TD type on the rate of the exothermic decomposition reaction, in the early stages of the selfheating process, of the chemical is assumed to be of the zeroth order in the thermal explosion theory [1], In other words, it is assumed in the thermal explosion theory that the concentration of the chemical remains virtually constant while the self-heating process is in the early stages, because the consumption of the chemical caused by the reaction can be neglected while the self-heating process is in the early stages. 

In the meantime, the A Tdijf pen runs almost parallel with the time axis on the strip chart of the two-pen strip-chart recorder after the start of the adiabatic control. This denotes that the state, A - T - Tqiiii 0, IS rcslizcd. in 8.nd around 2 cm of the chemical confined in the closed cell and subjected to the adiabatic self-heating test. The A Tdiff pen, however, comes to drift toward the plus side on the strip chart in the course of time. This denotes that the state, 7 > Tam, comes to occur in and around 2 cm of the chemical confined in the closed cell, in spite of the adiabatic control, because the rate of increase in temperature, i.e., the rate of the exothermic decomposition reaction, of 2 cm of the chemical confined in the closed cell and subjected to the adiabatic self-heating test... 

In general, there are many factors influencing the relationship between the rates of the exothermic and endothermic processes, that affect the carry-over in the flash smelting of oxidized lead-bearing feeds. They range fixrm the composition and dispersivity of the feed and carbonaceous fuel to the particular methods of feed preparation and the smelting conditions. Therefore, it is rather challenging to match the rates of heat release and heat consumption in the... 

The Chlorine Institute in PI52 reconunends that NCI3 concentration never be allowed to increase to more than 2%. This provides a maigin below the concentration of 6% at which the rate of the exothermic decomposition begins to accelerate. Euro Chlor [54] reports that 13% is a lower limit for detonation, suggests limits similar to the CFs in processing, and publishes recommendations for maximum concentrations under various circumstances. Variables include... 

Synthesis Temperature. Because of the exothermic nature of the ammonia synthesis reaction, higher temperatures increase reaction rates, but the equihbrium amount of ammonia decreases. Thermal degradation of the catalyst also increases with temperature. 

The catalyst for this type of reaction is generally an amine. These reactions are quite exothermic, and the selection of the amine plays an important role in the rate of the reaction as well as in the amount of heat generated. The processes utilized to make these types of products are either batch or continuous (25—27). 

The law of mass action, the laws of kinetics, and the laws of distillation all operate simultaneously in a process of this type. Esterification can occur only when the concentrations of the acid and alcohol are in excess of equiUbrium values otherwise, hydrolysis must occur. The equations governing the rate of the reaction and the variation of the rate constant (as a function of such variables as temperature, catalyst strength, and proportion of reactants) describe the kinetics of the Hquid-phase reaction. The usual distillation laws must be modified, since most esterifications are somewhat exothermic and reaction is occurring on each plate. Since these kinetic considerations are superimposed on distillation operations, each plate must be treated separately by successive calculations after the extent of conversion has been deterrnined (see Distillation). 

Hydroxy- 6-diazoandrost-5-en- l-one (96) To a stirred solution of 750 ml of methanol and 144 ml of 5 A sodium hydroxide is added 36 g (0.114 mole) of oximino ketone. Concentrated aqueous ammonia (56.6 ml, 0.850 mole) is then added followed by dropwise addition of 265 ml of cold 3 M sodium hypochlorite at a rate sufficient to maintain the temperature of the exothermic reaction mixture at 20 + 1° while cooling with an external ice bath. At temperatures below 20° appreciable amounts of a-mono- and a-dichloro ketones are obtained above 20° the chloramine decomposes before reacting with the oximino ketone. As soon as all of the sodium hypochlorite has been added, the ice bath is removed and the reaction mixture is allowed to warm to room temperature with continued stirring for 6 hr. The reaction mixture is diluted with an equal volume of water and extracted twice with... 

Since mixing of glycol and MA was very thorough and rapid this AT mirrors the progress of the exothermic nitration reaction. Note the strong influence of mixed acid water content on the nitration rate. This agrees with Oehman et al (Ref 56a), except that Roth et al observed... 

FIGURE 13.27 (a) The activation energy for an endothermic reaction is larger in the forward direction than in the reverse and so the rate of the forward reaction is more sensitive to temperature and the equilibrium shifts toward products as the temperature is raised, (b) The opposite is true for an exothermic reaction, in which case the reverse reaction is more sensitive to temperature and the equilibrium shifts toward reactants as the temperature is raised. 

There is a third explosion limit indicated in Figure 4.1 at still higher pressures. This limit is a thermal limit. At these pressures the reaction rate becomes so fast that conditions can no longer remain isothermal. At these pressures the energy liberated by the exothermic chain reaction cannot be transferred to the surroundings at a sufficiently fast rate, so the reaction mixture heats up. This increases the rate of the process and the rate at which energy is liberated so one has a snowballing effect until an explosion occurs. 

This space time is about 59% of that required for isothermal operation. This number may be somewhat low because the reaction is exothermic and the rate of the reverse reaction may be appreciable at the highest temperatures involved in our calculation. 

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