Alkane combustion

In this section, you will learn how to predict the reactions of different functional groups. You studied the most common reaction of alkanes, combustion, in your previous chemistry course. For this reason, the reactions of alkanes will not be considered here. The reactions of amines and ethers will be left for a later chemistry course. 

Alkanes react with oxygen, producing heat. This combustion can be observed in the burning of methane in home heating systems and in the gas ranges in many kitchens. The products of alkane combustion are always water and carbon dioxide. Here is a sample balanced equation for alkane combustion. 

Complete the following problems dealing with alkane combustion. 

The chapter tries to give an up-to-date account of all the main mathematical tools which have been used for the construction, investigation and reduction of complex reaction mechanisms. However, there are reviews which discuss some of these methods in more detail. Frenklach [9] has reviewed several techniques, developed until 1989, for the reduction of combustion mechanisms. Application of reduced chemical mechanisms in turbulent combustion has been reviewed by Seshadri and Williams [10]. Warnatz [4] has reviewed the relation of combustion modelling to detailed reaction mechanisms. The recent review of Griffiths [11] concentrates mainly on global mechanisms for the description of low-temperature alkane combustion. The review of Turanyi [12] gives an almost full account until... 

J.F. Griffiths, K.J. Hughes, M. Schreiber and C. Poppe, A Unified Approach to the Reduced Kinetic Modeling of Alkane Combustion, Comb, and Flame 1139 (1994) 533-540. 

In most, but not all circumstances, the core gas temperature, T, is the natural reference temperature for the compressed gas because the highest temperature at the end of compression is responsible for the development of spontaneous ignition in the shortest time [88, 95]. Exceptionally, when the compression heats the reactants to temperatures that correspond to the region of ntc for that particular mixture, combustion may be initiated in the cooler boundary layer region. That is, gases which, at the end of compression, are colder than those in the adiabatic core control the duration of the ignition delay. This was demonstrated by Schreiber and coworkers by the simulation of alkane combustion, using various reduced kinetic schemes, in computational fluid dynamic calculations [102-104]. 

The most extreme oxidation reactions of organic compounds occur when they hum in O2. Such combustion reactions (Section 6-8) are highly exothermic. When the combustion takes place in excess O2, the products are CO2 and H2O. Examples of alkane combustions are... 

P2.10 Data methane-octane normal alkane combustion enthalpies... 

The major field of hydrocarbon consumption is power supply. Energy evolved from alkane combustion is used in gas, diesel and jet engines. Nowadays, chemical processing of hydrocarbon raw materials, in particular alkanes, requires usually participation of heterogeneous catalysts and elevated temperatures (above 200-300 °C) [6], Natural gas is used mainly in the production of synthesis gas or hydrogen [6ej. Liquefiable components of natural gas find more extensive application. In the USA, the gas condensate and other liquefied components account for 18% of the overall production of liquid hydrocarbons and 70% of the raw material for the production of ethene and other valuable products. 

It is essential (though not always done) that the products of combustion be analyzed the assumption of complete combustion is not always an accurate one. Alkane combustion proceeds in a series of steps, in which CO is always predecessor to the final product CO 2- If only 0.1% of the carbon content of an alkane is oxidized only as far as CO, the resulting error in AfH will be 0.07 kcal per C atom. If an equivalent amount of carbon is reduced to graphite (solid soot/graphite is often observed after bomb combustion), the error is 0.1 kcal per C atom. 

In order to compare the stability of constitutional isomers, we look at the heat liberated when they each undergo combustion. For an alkane, combustion describes a reaction in which the alkane reacts with oxygen to produce CO2 and water. Consider the following example ... 

In Chapter 4, we consider only one reaction of alkanes—combustion. Combustion is an oxidation-reduction reaction. 

Babushok, V. Tsang, W. Inhibitor rankings for alkane combustion. Combust. Flame, 2000, 124, 488-506. 

Alkane combustion Alkene combustion Alkyne combustion... 

Only a relatively limited number of mechanisms are needed to describe the very large number of reactions in organic chemistry. Mechanisms enable us to understand how and why reactions occur, and what products are likely to form in them. In this chapter we ply mechanistic concepts to explain the effects of halogen-containing chemicals on the stratospheric ozone layer. We conclude with a brief discussion of alkane combustion and show how that process serves as a useful source of thermodynamic information about organic molecules. 

Gery, M.W., Whitten, G.Z., Killus, J.P., Dodge, M.C. A photochemical kinetics mechanism for urban and regional scale computer modeling. J. Geophys. Res. D94, 12925-12956 (1989) Glaude, P.A., Battm-LeClerc, F., Foumet, R., Warth, V., Come, G.M., Scacchi, G. Constmction and simplification of a model for the oxidation of alkanes. Combust. Flame 122, 451-462 (2000)... 

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