Stoichiometry theoretical yields

Click Coached Problems for a self-study module on stoichiometry theoretical yield. 

The theoretical yield of a product is the maximum quantity that can be expected on the basis of the stoichiometry of a chemical equation. The percentage yield is the percentage of the theoretical yield actually achieved. 

The amount of a product obtained from a reaction is often reported as a yield. The amount of product predicted by stoichiometry is the theoretical yield, whereas the amount actually obtained is the actual yield. The percent yield is the percentage of the theoretical amount that is actually obtained ... 

Step 3 Calculate the theoretical yield of product in grams or moles, based on the limiting reactant using simple stoichiometry. 

Since the stoichiometry indicates that 1 mole CC12F2 is produced per moleCCl4, the use of 1.80 mole CC14 will produce 1.80 moleCCl2F2. This is the theoretical yield of the reaction. 

The particular wood species we chose for this study is aspen (Populus tremuloides), which is plentiful in Canada and in the northern U.S.A. The chemical composition we found to be glucan 53.4%, xylan 14.9%, total carbohydrate 79.0%, lignin 17.1% and extractives 3.8%. We would expect total fermentable sugars of about 56% in this sample of aspen in anhydro form (Timell has reported about 60% in another sample (15)) which upon hydrolysis would yield about 1,250 lb wood sugars per ton of wood (dry basis), from the stoichiometry. Theoretical conversion of this sugar to ethanol would yield 640 lb or 81.1 gallons of anhydrous... 

Group Monomer Theoretical Measured stoichio- stoichiometry metry Yield in Charac-functional teristic side-groups products (per 100 C) ... 

Chemists use stoichiometry to predict the amount of product that can be expected from a chemical reaction. The amount of product that is predicted by stoichiometry is called the theoretical yield. This predicted yield, however, is not always the same as the amount of product that is actually obtained from a chemical reaction. The amount of product that is obtained in an experiment is called the actual yield. 

Calculate the theoretical yield of calcium oxide using stoichiometry. Then multiply the theoretical yield by the percentage yield to predict the actual yield. 

In this section, you have learned how the amount of products formed by experiment relates to the theoretical yield predicted by stoichiometry. You have learned about many factors that affect actual yield, including the nature of the reaction, experimental design and execution, and the purity of the reactants. Usually, when you are performing an experiment in a laboratory, you want to maximize your percentage yield. To do this, you need to be careful not to contaminate your reactants or lose any products. Either might affect your actual yield. 

Theoretical yield. The yield predicted by stoichiometry, that is, the maximum weight of product obtainable from a reaction as indicated by the relation of combining weights in the equation for the reaction. 

Use the following terms to create a concept map stoichiometry, excess reactant, theoretical yield, and mole ratio. 

The amount of product of a chemical reaction predicted by stoichiometry is called the theoretical yield. As shown earlier, if 3.75 g of nitrogen completely react, a theoretical yield of 4.55 g of ammonia would be produced. The actual yield of a chemical reaction is usually less than predicted. The collection techniques and apparatus used, time, and the skills of the chemist may affect the actual yield. 

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. 

Which do we calculate by using stoichiometry, the actual or the theoretical yield ... 

The stoichiometry of conversion of /3-carotene to retinol is still an unsettled issue. Central cleavage of /3-carotene theoretically yields 2 mol retinol per mole /3-carotene (Goodman and Huang, 1%5 Olson and Hayaishi, 1965 Olson, 1989) and eccentric cleavage of /3-carotene yields 1 mol retinol per mole /3-carotene (Olson, 1989, Krinsky et al., 1994). Brubacher and Weiser (1985) determined the retinol equivalent of /3-carotene in vivo using rats and chicks and found that 1 mol of absorbed /3-carotene yielded 1 mol retinol. Because the body reserves of retinol in these animals were low, the yield of retinol from /3-carotene was probably maximal. Based on these in vivo results, a ratio of 1 mol retinol per mole /3-carotene (after absorption) was used in constructing the present compartmental model of the dynamics of /3-carotene metabolism. 

We can rate the efficiency of a reaction by calculating how much product would form under perfect or ideal conditions and then comparing the actual measured result with this ideal. The ideal amount of product is called the theoretical yield, and it is obtained by working a stoichiometry problem. Measuring the amount of product formed gives us the actual yield. From the ratio of the actual yield to the theoretical yield, we can calculate the percentage yield. 

We know the actual yield from the experiment. To calculate the percentage yield, first we need to find the theoretical yield. We can do that by calculating the maximum quantity of product that could form, based on the stoichiometry of the reaction. Once we have both the theoretical yield and the actual yield, finding the... 

Reactant, p. 73 Stoichiometric amount, p. 81 Stoichiometry, p. 77 Theoretical yield, p. 83... 

The theoretical yield of product is the maximum amount of product that can be obtained by a reaction from given amounts of reactants. It is the amount that you calculate from the stoichiometry based on the limiting reactant. In Example 3.16, the theoretical yield of acetic acid is 27.3 g. In practice, the actual yield of a product may be much less for several possible reasons. First, some product may be lost during the process of separating it from the final reaction mixture. Second, there may be other,... 

CIA Demonstration Self-Inflating Hydrogen Balloons Theoretical Yield and Percent Yield A Problem Involving the Combined Concepts of Stoichiometry... 

---