Stoichiometric calculation percent yield

The problem asks for a yield, so we identify this as a yield problem. In addition, we recognize this as a limiting reactant situation because we are given the masses of both starting materials. First, identify the limiting reactant by working with moles and stoichiometric coefficients then carry out standard stoichiometry calculations to determine the theoretical amount that could form. A table of amounts helps organize these calculations. Calculate the percent yield from the theoretical amount and the actual amount formed. 

The yield of a reaction is the amount of product obtained. This value is nearly always less than what would be predicted from a stoichiometric calculation because side-reactions may produce different products, the reverse reaction may occur, and some material may be lost during the procedure. The yield from a stoichiometric calculation on the limiting reagent is called the theoretical yield. Percent yield is the actual yield divided by the theoretical yield times 100% ... 

Stoichiometry is the quantitative study of products and reactants in chemical reactions. Stoichiometric calculations are best done by expressing both the known and unknown quantities in terms of moles and then converting to other units if necessary. A limiting reagent is the reactant that is present in the smallest stoichiometric amount. It limits the amount of product that can be formed. The amount of product obtained in a reaction (the actual yield) may be less than the maximum possible amount (the theoretical yield). The ratio of the two is expressed as the percent yield. 

Before going to lab, a student read in her lab manual that the percent yield for a difficult reaction to be studied was likely to be only 40.% of the theoretical yield. The student s prelab stoichiometric calculations predict that the theoretical yield should be 12.5 g. What is... 

Example 9.9 Stoichiometric Calculations Determining Percent Yield... 

Other Practical Matters in Reaction Stoichiometry— Stoichiometric calculations sometimes involve additional factors, including the reaction s actual yield, the presence of by-products, and how the reaction or reactions proceed. For example, some reactions yield exactly the quantity of product calculated—the theoretical yield. When the actual yield equals the theoretical yield, the percent yield is 100%. In some reactions, the actual yield is less than the theoretical, in which case the percent yield is less than 100%. Lower yields may result from the formation of by-products, substances that replace some of the desired product because of reactions other than the one of interest, called side reactions. Some stoi-... 

Since the DGEBA/DDS networks are tetrafunctional and of stoichiometric composition, the theoretical value of z is 2. Furthermore, the crosslink concentration, c, is simply the DDS molecule concentration. Performing the necessary calculations yields the theoretical M, listed in Table 4. Compared to the experimental M, the theoretical values are very consistent. If it is assumed that the DGEBA/DDS networks are not phantom-like (i.e., A = 1), then the ratio of the theoretical and experimental values may serve as an estimate of the dilation factor, These ratios are listed in Table 4, and show that is approximately unity for all the networks. If the experimental M had been calculated using the actual network densities (instead of q = 1 g/cm), the ratios would be even closer to unity, being reduced by approximately 20 percent. 

Calculations All gas measurements are reported at 60 °F. and 760 mm. mercury pressure. The hydrogen feed rate of 12,000 cu. ft. per barrel was 1.1 times the stoichiometric amount of about 10,890 cu. ft. needed to convert the crude oil completely to methane, hydrogen sulfide, ammonia, and water. The yield of methane as volume percent of stoichiometric was calculated by dividing the volume in cubic feet per barrel by 8740, which was the stoichiometric yield at the given conditions. 

Having validated the mechanism on ammonia-oxygen flames, the yield of NO from nitrogen doped CH4-air flames was examined. Both NH3 and NO doping were investigated. Only post-flame NO concentrations were measured. These are compared with calculations of the full kinetics and with adiabatic equilibrium calculations. The calculated profiles indicate the complexity of the NO dynamics in these flames. The temperature and major species profiles in the undoped flames had been studied in earlier work( ). Three near stoichiometric methane-air flames having initial equivalence ratios(0) of 0.8, 1.0 and 1.2 are diluted with less than 5 volume percents of NH3 or NO. In this section NO concentration is expressed both as a mole fraction and as a fraction of the total nitrogen concentration ... 

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