Reactive Gaseous Mixtures

A reaction is said to be stoichiometric when the fuel and oxygen consume each other completely, forming carbon dioxide (C02) and water (H20) under ideal conditions. The equivalence ratio is the parameter relating a mixture proportion to stoichiometry. It is defined as the ratio of fuel-to-oxygen amounts times the stoichiometric ratio of oxygen-to-fuel amounts. If there is an excess of fuel, then the mixture is called fuel-rich or rich, and the equivalence ratio is greater than 1, and if there is an excess of oxygen, then it is called fuel-lean or lean and the equivalence ratio is less than 1. 

Not all mixtures of reactants lead to combustion. There is a limiting amount of fuel per amount of oxygen, above which the reaction does not take place. This is called the upper flammability 

The net heat that is liberated in the overall combustion reaction is called heat of combustion, and is equal to the heat released by the exothermic reactions minus the heat absorbed by the endothermic reactions. The heat of combustion is partially stored in the combustion product as sensible energy, thus increasing their temperature, and partially lost to the environment. The maximum temperature that the combustion products can ever reach is given for the ideal conditions of no heat losses or adiabatic combustion. This is the called adiabatic temperature and it sets the theoretical maximum limit for the temperature of a flame (for methane/air mixtures this is 1950°C at atmospheric conditions). The tabulated values of adiabatic temperature for different gaseous fuels can be found in [1,2], 

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When a promoter is added continuously to the reactive gaseous mixture, as e.g. in the case of a few ppm C2H2C12 addition to C2H4 and 02 during C2H4 epoxidation on Ag catalysts, this promoter (C2H2C12) is also sometimes referred to as a moderator. 

Silicon carbide can be made by chemical vapor deposition on a substrate heated to around 1300°C (DeBolt et al, 1974). The substrate can be tungsten or carbon. The reactive gaseous mixture contains hydrogen and alkyl silanes. Typically, a gaseous mixture consisting of 70% hydrogen and 30% silanes is introduced at the... 

The production of Si-H containing compounds 7b-9b as the major products suggests that both 6b and hydrogen chloride reacted with the same silicon atom, and the reactivities of the two reactants are comparable. The minor products 3b and 4b are derived from the direct reaction of silicon with a gaseous mixture of (chloromethyl)dichloromethyl-silane, formed by the decomposition of the reactant 6b during the reaction, and hydrogen chloride. It has been reported that tris(chlorosilyl) methanes do not decompose to bis(chlorosilyl)methanes under the reaction conditions.20... 

The reactivity experiments were performed in a flow apparatus using a fixed bed flat reactor, whose internal dimensions (width, thickness and height) were 3.7, 0.2 and 9 cm, respectively. The photoreactor was irradiated on one side by a 1000 W Hg-Xe lamp (Hanovia L 5173). An He (.99.5 % purity) or an air flow was bubbled in a bottle containing ethanoic acid. The gaseous mixture... 

Compared to pure oxygen, chlorine is even more reactive. The self-ignition temperature of gaseous mixtures of organic vapours with chlorine is much lower than that of their mixtures with oxygen. Natural light can split the chlorine molecule to produce reactive chlorine radicals. Many reactions of chlorine take place near the ambient temperature. The combustion of iron in chlorine can be initiated at temperatures slighly above 100°C. 

These acids can be used alone or as mixtures. It is especially advantageous to use a mixture of liquid and gaseous acids. The gaseous acid will stabilize free monomer in the headspace of a container, while the liquid acid will prevent premature polymerization of the bulk monomer or adhesive. However, it is important to use only a minimum amount of acid, because excess acid will slow initiation and the formation of a strong adhesive bond. It can also accelerate the hydrolysis of the alkyl cyanoacrylate monomer to 2-cyanoacrylic acid, which inhibits the polymerization of the monomer and reduces molecular weight of the adhesive polymer. While carboxylic acids inhibit the polymerization of cyanoacrylate monomer, they do not prevent it completely [15]. Therefore, they cannot be utilized as stabilizers, but are used more for modifying the reactivity of instant adhesives. 

The octahedral hexafluorides are obtained directly from the elements and both are volatile, extremely reactive and corrosive solids, RhFg being the least stable of the platinum metal hexafluorides and reacting with glass even when carefully dried. They are thermally unstable and must be frozen out from the hot gaseous reaction mixtures, otherwise they dissociate. 

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