Explosion limits sensitized reaction

Disadvantages associated with some organic solvents include toxicity flammabiHty and explosion ha2ards sensitivity to moisture uptake, possibly leading to subsequent undesirable reactions with solutes low electrical conductivity relatively high cost and limited solubiHty of many solutes. In addition, the electrolyte system can degrade under the influence of an electric field, yielding undesirable materials such as polymers, chars, and products that interfere with deposition of the metal or alloy. 

It should be evident from this discussion that the first explosion limit will be quite sensitive to the nature of the surface of the reaction vessel and its area. If the surface is coated with a material that inhibits the surface chain termination process, the first explosion limit will be lowered. Inert foreign gases can also have the effect of lowering the first explosion limit, since they can hinder diffusion to the surface. If something like spun glass or large amounts of fine wire are inserted, one can effect an increase in the first explosion limit by changing the surface/ volume ratio of the system. 

A bleach solution was being prepared by mixing solid sodium chlorite, oxalic acid, and water, in that order. As soon as water was added, chlorine dioxide was evolved and later exploded. The lower explosive limit of the latter is 10%, and the mixture is photo- and heat-sensitive [1]. It was calculated that the heat of reaction (1.88 kJ/g of dry mixture) would heat the expected products to an adiabatic temperature approaching 1500°C with an 18-fold increase in pressure in a closed vessel [2],... 

The second explosion limit must be explained by gas-phase production and destruction of radicals. This limit is found to be independent of vessel diameter. For it to exist, the most effective chain branching reaction (3.17) must be overridden by another reaction step. When a system at a fixed temperature moves from a lower to higher pressure, the system goes from an explosive to a steady reaction condition, so the reaction step that overrides the chain branching step must be more pressure-sensitive. This reasoning leads one to propose a third-order reaction in which the species involved are in large concentration [2], The accepted reaction that satisfies these prerequisites is... 

The feature which is unique to the chain-branching system is the paradoxical, upper, or second explosion limit. Plere one observes that a reaction proceeding with explosive speed at pressures below the limit is effectively (picnched on raising the pressure. In addition, the pressure limit increases if the temperature increases, just opposite to the behavior at the first and third limits. It is the existence of this limit that is the real evidence of the branching chain. It is observed that the limit is much less sensitive to surface-volume effects than is the first limit, while added inert gases always tend here to lower the limit (i.e., quench the explosion). 

Below the first explosion limit the rate of reaction seems to be negligibly slow. Above the second explosion limit, studies of the rate of the normal" reaction have shown considerable irreproducibility among different laboratories and even in the same laboratory. The rates are remarkably sensitive... 

Measurements by Lewis and von Elbe [23] of initial reaction rates at 530 °C in a KCl coated Pyrex reaction vessel of diameter 7.4 cm are shown in Fig. 6. For constant total pressure, the rate varies little in hydrogen-rich mixtures but diminishes when the oxygen content increases. The reaction seems more sensitive to the total pressure than it is to mixture composition. The rate diminishes with pressure until the neighbourhood of the second explosion limit is reached. At the limit itself the rate becomes infinite, and very near the limit, within a few torr, Lewis... 

AMINO-l-METHYLBENZENE (1 OS-44-1) C7H9N Combustible liquid [explosion limits in air (vol %) 1.1 to 6.6 flash point 186°F/86°C autoignition temp 899°F/482°C Fire Rating 2]. Light causes slow decomposition. Violent reaction with strong oxidizers nitric acid. May form heat-sensitive explosive materials with digold ketenide. Incompatible with acids, acid... 

AMINO-2-METHYLPROPANE (78-81-9) C4H N Forms explosive mixture with air [explosion limits in air (vol %) 3.4 to 9.0 flash point 15°F/-9°C autoignition tenqi 712°F/378°C Fire Rating 3]. An organic base. Violent reaction with strong oxidizers nitric acid cellulose nitrate (of high siurface area) l-chloro-2,3-epoxypropane (exothermic). May form heat-sensitive... 

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