Percentage yield calculating

Use the mole concept to do percentage-yield calculations. (Section 5.11)... 

To determine the percentage yield, a one metallocene to two dextran units, was chosen for the basis of percentage yield calculations. The yields of Hf and Zr were similar and were generally greater than Ti. Maximum yields for Hf and Zr substitution were 80-95% while for Ti it was about 60% with the percentage yields for Hf generally a little higher than for Zr. This trend is consistent with what would be predicted from the HSAB approach (i.e., Hf>Zr>Ti). As expected, this order is the same as that found for the polyether formation. 

To calculate percentage yield, one needs to know the theoretical value that can be obtained, based on material balance, and if 100% of the reactant(s) is converted to product. After obtaining the experimental value (actual yield), divide it by the theoretical value, then multiply by 100 to get percentage yield.8... 

The theoretical yield of a reaction is the maximum quantity (amount, mass, or volume) of product that can be obtained from a given quantity of reactant. The quantities of products calculated from a given mass of reactant in Section L were all theoretical yields. The percentage yield is the fraction of the theoretical yield actually produced, expressed as a percentage ... 

STRATEGY Begin by writing the chemical equation for the complete oxidation of octane to carbon dioxide and water. Then calculate the theoretical yield (in grams) of CO, by using the procedure in Toolbox L.l. To avoid rounding errors, do all the numerical work at the end of the calculation. To obtain the percentage yield, divide the actual I mass produced by the theoretical mass of product and multiply by 100%. 

Calculate the percentage yield of carbon dioxide from the fact that only 1.84 kg was produced. 

EXAMPLE M.3 Calculating percentage yield from a limiting reactant... 

STRATEGY First, the limiting reactant must be identified (Toolbox M.l). This limiting reactant determines the theoretical yield of the reaction, and so we use it to calculate the theoretical amount of product by Method 2 in Toolbox L.l. The percentage yield is the ratio of the mass produced to the theoretical mass times 100. Molar masses are j calculated using the information in the periodic table inside the front cover of this i book. 

Calculate the theoretical and percentage yields of the products of a reaction, given the mass of starting material (Example M.l). 

In order to fill four 250. mL bottles, 1.00 L 02 is actually required. However, more than 1.00 L 02 must be produced since some 02 will be lost in the process. If 25% of 02 will be wasted, the percentage yield of the process is 75%. The theoretical amount of 02 that must be produced can be calculated ... 

Many chemical reactions do not run to completion. Particularly in organic chemistry, side reactions can occur and product can be lost during purification procedures. The yield of product will, therefore, be less than 100%. The percentage yield can be calculated from the following equation ... 

Example On oxidation of 50.0 g of ethanol, 59.0 g of ethanoic acid were obtained. Calculate the percentage yield of the product (molar masses ethanol C2H5OH = 46.0gmor, ethanoic acid CH3CO2H = 60. Ogmoh1). 

The percentage yields have been based on the amount of aniline taken. It would probably be more legitimate to base the calculation on the amounts of aniline taken and of nitrobenzene not recovered, since undoubtedly the latter is reduced to aniline during the course of the reaction. If this be done, the yield is found to be only 55 to 60 per cent of the calculated amount. 

The pure solid can be dried and weighed. A percentage yield can be calculated from its mass. The pure solid will often be subjected to analysis by melting point and thin-layer chromatography (see pp. 94-95). 

Assuming that 5-36 g of ethyl benzoate were used in the experiment and that 3-24 g of benzoic acid were obtained, the percentage yield of benzoic acid can be calculated as ... 

If 5 06 g of 2-hydroxybenzoic acid produced 3-20 g of aspirin, calculate the percentage yield for the reaction. 

For the sake of brevity, the yield data for all the individual components are not reported in Table II and subsequent tables. The yield of unreported components (usually Cs-i- olefins and naphthenes) can be calculated as 100 minus percentage yield of the reported components. Results shown in Table ll indicate that thermally treated ZSM-5 produced a high yield of Ce to Ce aromatics, Cs and C4 hydrocarbons. Steam treatment of ZSM-5 reduced cracking activity and increased the selectivity for Cs to C aliphatics at the expense of aromatics. The olefin to paraffin ratio in the product also increased upon steaming. 

Table 6.1 lists the stoichiometric yields of hydrogen and percentage yields by weight from steam reforming of some representative model compounds present in biomass pyrolysis oils, and also several biomass and related materials. The table also shows the equilibrium yield of H2, as a percentage of the stoichiometric yield, predicted by thermodynamic calculations at 750 °C and vdth a steam-to-carbon (S/C) ratio of 5 [32]. 

The yield and selectivity of a particular product were defined as mole percentage yield and selectivity on a carbon-accounted-for basis. As for the yield of "other acid", the yield was calculated basing on the asumption that the acid was acetic acid or maleic anhydride, because the main acids, besides benzoic acid, were found to be acetic acid and maleic anhydride. The contact time was defined as (volume of catalyst used [ml])/(total flow rate [ml/s]). 

Self-Test M.2A When 24.0 g of potassium nitrate was heated with lead, 13.8 g of potassium nitrite was formed in the reaction given in Self-Test M.l A. Calculate the percentage yield of potassium nitrite. 

It may be of interest to show how the reversible work for any percentage yield can be calculated by another equation which does not involve a graphical integration. Designating the feed, concentrated brine, and fresh water streams as 1, 2, and 3, respectively, we can write for an isothermal, reversible process... 

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