Yield, actual percent

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 ... 

In the problem above, the amount of product calculated based upon the limiting reactant concept is the maximum amount of product that will form from the specified amounts of reactants. This maximum amount of product is the theoretical yield. However, rarely is the amount that is actually formed (the actual yield) the same as the theoretical yield. Normally it is less. There are many reasons for this, but the principal one is that most reactions do not go to completion they establish an equilibrium system (see Chapter 14 for a discussion on chemical equilibrium). For whatever reason, not as much product as expected is formed. We can judge the efficiency of the reaction by calculating the percent yield. The percent yield (% yield) is the actual yield divided by the theoretical yield and the resultant multiplied by 100 in order to generate a percentage ... 

Chemists are usually interested in the efficiency of a reaction. The efficiency is expressed by comparing the actual yield to the theoretical yield. The percent yield is the ratio of actual yield to theoretical yield multiplied by 100 percent. 

When a quantity of product is calculated from a quantity or quantities of reactants, as was done in Sections 10.1 through 10.4 of this chapter, that quantity of product is called the theoretical yield. When a reaction is run, however, less product than the calculated amount is often obtained Some of the product may stay in the solution in which the reaction was run some side reaction may use up some of the reactants or the reaction may be stopped before it is completed. No matter why, the fact is that many reactions produce less product than the calculated quantity that is, the actual yield is less than the theoretical yield. No reaction can produce more than the theoretical yield. The percent yield is defined as 100% times the ratio of the actual yield to the theoretical yield ... 

The amount of product produced when a reaction runs to completion is called the theoretical yield. The amount of actual product after a real experiment is the actual yield. As mentioned above, reactions often don t run to completion, and sometimes there are competing reactions that reduce the actual yield. Actual yield divided by the theoretical yield, times 100, gives the percent yield. 

Determine which of two reactants is the limiting reactant (Section 4.4). Explain the differences among actual yield, theoretical yield, and percent yield,... 

When actual yield is less than theoretical yield, you express the efficiency of the reaction as percent yield. The percent yield of a reaction is the ratio of the actual yield to the theoretical yield expressed as a percent. Suppose the actual yield was 3.86 g of ammonia. Then, the percent yield could be calculated by using the following equation. 

Percent yield = actual yield ioo% theoretical yield... 

The theoretical yield of a reaction is the calculated amount of product that should be obtained in a reaction. But in practice, something less than the theoretical yield, the actual yield, is obtained. For many reasons—impure reagents, solubility problems, decomposition, or spillage—the amount of product isolated from a reaction is frequently less than that calculated from the balanced equation. The fraction of the theoretical yield actually obtained in a reaction is expressed as the percent yield of the reaction. 

Theoretical yield, actual yield, and percent yield (page 209) ... 

Whatever the exact explanation, on the process side, the mild solvent extraction step of the heavier feed fractions resulted in no less than doubling the hydrocracker space velocity, a spectacular benefit. Needless to say, feedstock solvent extraction became a popular process step. Lube yields based on feed also improved by 5 vol. % although based on crude, lube yields actually declined (Table 7.7). As IFP had found previously, a decrease in feed dewaxed VI reduced yields at a constant product VI, in Sun s case by about 1.3 volume percent per VI change (Table 7.8). 

Because the actual yield must be less than the theoretical yield, the percent yield is always less than 100%. In multistep reaction sequences, the percent yield of each step is expressed as a fraction and multiplied by the others to find the overall yield. The result may sometimes be surprising. For example, suppose a six-step reaction sequence has a 90.0% yield for each step, which is quite high. Even so, the overall percent yield would be... 

E0EIQ Identify which type of yield—theoretical yield, actual yield, or percent yield—is a measure of the efficiency of a chemical reaction. 

This is the theoretical yield of Li3N. The actual yield is given in the problem (5.89 g). The percent yield is % yield = actual yield 5 ... 

The wording of the problem suggests that the actual yield is less than the theoretical yield. The percent yield will be equal to the percent purity of the iron(lll) oxide. We find the theoretical yield ... 

If we know the chemical equation and the amounts of reactants, we can calculate the theoretical yield of that reaction. But in reality, the yield depends on many other factors also. Most of the time in synthesis reactions, even in your own lab experiments, you probably noticed that the actual yield is lower than the theoretical yield. The percent yield denotes the amount of actual yield in terms of the theoretical yield. The formula to find the percent yield is given below ... 

Your text talks about several sorts of "yield" when experiments are performed in the laboratory. Students often confuse these terms. Define, compare, and contrast what are meant by theoretical yield, actual yield, and percent yield. 

A limiting reactant is completely consumed in a reaction. When it is used up, the reaction stops, thus limiting the quantities of products formed. The theoretical yield of a reaction is the quantity of product calculated to form when aU of the limiting reactant reacts. The actual yield of a reaction is always less than the theoretical yield. The percent yield compares the actual and theoretical yields. 

Limiting Reactant, Theoretical Yield, and Percent Yield The limiting reactant in a chemical reachon is the reactant that limits the amount of product that can be made. The theoretical yield in a chemical reaction is the amount of product that can be made based on the amount of the limihng reactant. The actual yield in a chemical reachon is the amount of product actually produced. The percent yield in a chemical reaction is the actual yield divided by theorehcal yield times 100%. 

In a chemical reaction, what are the actual yield and percent yield ... 

Given two of the following, or information from which two of the following may be determined, calculate the third theoretical yield, actual yield, percent yield. 

General format (1) Given actual and theoretical yields, find percent yield or (2) given percent yield and either the reactant quantity or the product quantity, find the unknown quantity. 

Percent yield Actual and theoretical yields Percent yield... 

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