Carbon, molar balances

C02 does, however introduce a carbon molar balance into Appendix B s derivation. It is ... 

Rogers defines the system according to Figure 2. He sets up elementary molar balances with respect to carbon, hydrogen, oxygen, nitrogen, and helium. The nomenclature adopted in this thesis is used to present Rogers mathematical models. 

One molecule (or mole) of propane reacts with five molecules (or moles) of oxygen to produce three molecules (or moles) or carbon dioxide and four molecules (or moles) of water. These numbers are called stoichiometric coefficients (v.) of the reaction and are shown below each reactant and product in the equation. In a stoichiometrically balanced equation, the total number of atoms of each constituent element in the reactants must be the same as that in the products. Thus, there are three atoms of C, eight atoms of H, and ten atoms of O on either side of the equation. This indicates that the compositions expressed in gram-atoms of elements remain unaltered during a chemical reaction. This is a consequence of the principle of conservation of mass applied to an isolated reactive system. It is also true that the combined mass of reactants is always equal to the combined mass of products in a chemical reaction, but the same is not generally valid for the total number of moles. To achieve equality on a molar basis, the sum of the stoichiometric coefficients for the reactants must equal the sum of v. for the products. Definitions of certain terms bearing relevance to reactive systems will follow next. 

Concentration limits for chloride and acetate in PN typically are linked to limitations for sodium and potassium. The usual ratio of chloride acetate in PN is about 1 1 to 1.5 1. Chloride and acetate primarily play a role in acid-base balance. Acetate is converted to bicarbonate at a 1 1 molar ratio. This conversion appears to occur mostly outside the liver. Bicarbonate never should be added to or coinfused with PN solutions. This can lead to the release of carbon dioxide and potentially result in the formation of calcium or magnesium carbonate (very insoluble salts). 

It is also possible to prepare a standard solution of calcium carbonate accurately using an analytical balance and a volumetric flask, as was suggested previously for EDTA, and pipetting an aliquot (a portion of a larger volume) of this solution into the reaction flask in preparation for the standardization of the EDTA solution. In this case, the concentration of the calcium carbonate solution is first calculated from the weight-volume preparation data (refer back to Example 4.2) and then the molarity of the EDTA solution is determined using Equation (5.54). 

In the total inorganic carbon balance of equation 8.94, we neglected the presence of some species. Table 8.9 shows that this approximation is reasonable although, for accurate calculations, we should also have considered bicarbonates CaHC03 and MgHCO and the soluble carbonate CaCO . Note also that sulfates occur in negligible molar proportions and that carbonate alkalinity coincides with total alkalinity. 

L volumetric flask and adding water up to the mark. Another solution was prepared by adding 0.530 g of anhydrous sodium carbonate to a 100.0-mL volumetric flask and adding water up to the mark. Then, 25.00 mL of the latter solution was pipetted into a flask and titrated with the diluted acid. The stoichiometric point was reached after 26.50 mL of acid had been added, (a) Write the balanced equation for the reaction of HCl(aq) with Na2C03(aq). (b) What is the molarity of the original hydrochloric acid ... 

Fj Is the molar feed flux of fixed carbon, and subscript 7 refers to fixed carbon. Finally, the energy balance leads to the following equation for the temperature distribution, with particle and gas temperatures taken to be equal ... 

This is how we know how to balance chemical equations and work out the masses reacting together, because we know that equal molar masses contain the same numbers of particles. In a chemical equation like C + 02 —> C02, we always know that there will be one mole of carbon atoms reacting with one mole of oxygen molecules (02) to give one mole of carbon dioxide. Providing the chemical equation balances, any fraction of moles will also be true. One-tenth of a mole of carbon will require one-tenth of a mole of oxygen gas molecules (02), to make one-tenth of a mole of carbon dioxide gas (C02). 

A healthy 17-year-old boy, who complained of dental sensitivity that occurred only when he consumed fizzy drinks, presented with marked tooth wear. All the teeth were involved, especially the premolars and permanent molars. He ate a poorly balanced diet, with 500 ml carbonated drinks twice daily. He subsequently admitted to frequent MDMA abuse. 

Almost all the evidence showing that phytate decreases zinc absorption in man and animals is based on pure phytate added to the diet. The effect of natural phytate is variable (18). It has, however, been reported that phytate in bran affected zinc bioavailability in the same way as sodium phytate (19). Dietary fibre in the rural Iranian diet was considered to be the main cause of zinc deficiency in Iran (20). However, the addition of 26 g of fibre from various sources to the American diet did not have any significant effect on the zinc requirements of male adults (21). Similarly, Indian men consuming a diet containing only 10.8 mg of zinc were reported to be in balance in spite of a dietary fibre intake of 50 g per day (22). Moreover, the presence of fibre and phytate in soy flour did not affect the bioavailability of zinc added as zinc carbonate, to the diet of rats (17), although others (23) have reported that the bioavailability of zinc in breakfast cereals depends mainly on their phytate-zinc molar ratio. Our results indicate that there is some, as yet, undetermined difference in the phytate or the fibre of cereals which affects the bioavailability of zinc. It may be some component of dietary fibre (24) or the intrinsic differences in the protein-phytate-mineral complex (10). 

The values for the organism yield constants are assumed to be somewhat higher than for acetic acid since they are expressed on a molar basis and more than one species may participate in the reaction. The yield constants for carbon dioxide and methane are developed from the oxidation-reduction balances. 

In theory, gasification processes can be designed so that the exothermic and endothermic reactions are thermally balanced. For example, consider reactions 2 and 5. The feed rates could be controlled so that the heat released balances the heat requirement. In this hypothetical case, the amount of oxygen required is 0.27 mol/mol of carbon, the amount of steam required is 0.45 mol/ mol of carbon, and the oxygen-to-steam molar ratio is 0.6 ... 

From the balanced chemical equation, you know that 2 mol of butane reacts with 13 mol of oxygen, producing 8 mol of carbon dioxide and 10 mol of water vapor. By examining this balanced equation, you are able to find mole ratios of substances in this reaction. Avogadro s principle states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles. Thus, when gases are involved, the coefficients in a balanced chemical equation represent not only molar amounts but also relative volumes. For example, if 2 L of butane reacts, the reaction involves 13 L of oxygen and produces 8 L of carbon dioxide and 10 L of water vapor. 

The data in Tables I-III have been used to calculate elemental balances. The results are shown in Table V with all of the numbers put on a molar basis and normalized to 100 organic carbons in the starting shale. This treatment makes it easy to follow the movement of the elements and simplifies the discussion of molecular transformations occurring during retorting. The recovery of carbon (organic plus inorganic) is 95-96% for each experiment. 

The process is fed with three streams ethane, ethylene, and chlorine. The ethane and ethylene streams have the same molar flow rate, and the ratio of chlorine to ethane plus ethylene is 1.5. The ethane/ethylene stream also contains 1.5 percent acetylene and carbon dioxide. (For this problem, just use 1.5 percent carbon dioxide.) The feed streams are mixed with an ethylene recycle stream and go to the first reactor (chlorination reactor) where the ethane reacts with chlorine with a 95 percent conversion per pass. The product stream is cooled and ethyl chloride is condensed and separated. Assume that all the ethane and ethyl chloride go out in the condensate stream. The gases go to another reactor (hydrochlorination reactor) where the reaction with ethylene takes place with a 50 percent conversion per pass. The product stream is cooled to condense the ethyl chloride, and the gases (predominately ethylene and chlorine) are recycled. A purge or bleed stream takes off a fraction of the recycle stream (use 1 percent). Complete the mass balance for this process. 

Conversions were cdculated as the difference between the outlet and inlet molar flow rates of methane or oxygen, divided by their inlet flow rates. The CO and H2 selectivities were calculated as the molar flow rates of CO and H2 in the effluent divided by the total amount of carbon oxides and H2 and H2O in the effluent respectively. Water flow rates were calculated by mass balance. 

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