Carbon-hydrogen combustion calculations

Suppose we burn 46 grams of ethanol. Collection of the products yields 88 grams of carbon dioxide and 54 grams of water. We wish to learn the relative numbers of carbon, hydrogen, and oxygen atoms in the compound, and we can do this by calculating the number of moles of carbon dioxide and water produced by the combustion of the 46 gram sample. Therefore, we calculate ... 

A fuel oil is analyzed and found to contain 85.0 wt% carbon, 12.0% elemental hydrogen (H), 1.7% sulfur, and the remainder noncombustible matter. The oil is burned with 20.0% excess air, based on complete combustion of the carbon to CO2, the hydrogen to H2O, and the sulfur to SO2. The oil is burned completely, but 8% of the carbon forms CO. Calculate the molar composition of the stack... 

To model a packed bed of wood particles pyrolysis and char conversion schemes can be selected from the database. Homogenous reactions within the void space are modelled by describing each volume cell in the numerical grid of the flow model as a continuous stirred reactor. Due to the lack of reliable kinetic data for the conversion of gaseous species under packed bed conditions, only the conversion of hydrogen and carbon monoxide is currently taken into account. For the combustion of hydrogen an infinite rate is assumed whereas the conversion of carbon monoxide is calculated according to [17]. 

Several companies offer instruments capable of determining carbon, hydrogen, nitrogen and some other elements [72]. Such instruments feature an automatic sample injector. Samples are normally encased in sealed capsules. There is also a small computer which integrates peak areas and performs all the necessary calculations, which in some instances include the calculations of chemical formulae the computer also prints out the results. Finally, the new instruments feature advanced combustion and chromatographic separation systems. 

There is one method that is generally applicable if the compound burns easily to form definite products. The heat of formation of a compound can be calculated from the measured value of the heat of combustion of the compound. The combustion reaction has one mole of the substance to be burned on the reactant side, with as much oxygen as is necessary to burn the substance completely organic compounds containing only carbon, hydrogen, and oxygen are burned to gaseous carbon dioxide and liquid water. 

EMPIRICAL FORMULAS FROM ANALYSIS (SECTION 3.5) The empirical formula of any substance can be determined from its percent composition by calculating the relative number of moles of each atom in 100 g of the substance. If the substance is molecular in nature, its molecular formula can be determined from the empirical formula if the molecular weight is also known. Combustion analysis is a special technique for determining the empirical formulas of compounds containing only carbon, hydrogen, and/or oxygen. 

The water formed in this combustion, and that transpiring in the lungs with the carbonated hydrogen (hydrogene carbone), were calculated from the oxygen used up, the carbonic acid formed, and the water exhaled by the lungs, and comparison with the water evolved by cutaneous transpiration. The loss by transpiration in 24 hrs. was found to be i lb. 14 oz. and by respiration 15 oz. 

Combustion of alkanes is an example of oxidation-reduction Although It IS possible to calculate oxidation numbers of carbon m organic mole cules It IS more convenient to regard oxidation of an organic substance as an increase m its oxygen content or a decrease m its hydrogen content... 

The deterrnination of hydrogen content of an organic compound consists of complete combustion of a known quantity of the material to produce water and carbon dioxide, and deterrnination of the amount of water. The amount of hydrogen present in the initial material is calculated from the amount of water produced. This technique can be performed on macro (0.1—0.2 g), micro (2—10 mg), or submicro (0.02—0.2 mg) scale. Micro deterrninations are the most common. There are many variations of the method of combustion and deterrnination of water (221,222). The oldest and probably most reUable technique for water deterrnination is a gravimetric one where the water is absorbed onto a desiccant, such as magnesium perchlorate. In the macro technique, which is the most accurate, hydrogen content of a compound can be routinely deterrnined to within 0.02%. Instmmental methods, such as gas chromatography (qv) (223) and mass spectrometry (qv) (224), can also be used to determine water of combustion. 

The calculations of the carbon emission reduction are based on the deviation from the reference-system gasoline in a combustion engine. If reference systems with higher efficiencies are applied, e.g., hybrid-electric vehicles, the total carbon emission reduction of the hydrogen path is lower. In this case, a modern CAES power plant might have benefits. 

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