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Limiting Reactant and Percentage Yield

In the cases we have considered so far, the reactants were present in the exact ratios necessary for them all to be completely consumed in forming products. This is not the usual case, however. It is necessary to have methods for describing cases in which one of the reactants may not be present in sufficient amount and in which conversion to products is less than complete. [Pg.41]

Suppose arbitrary amounts of reactants are mixed and allowed to react. The one that is used up first is called the limiting reactant some quantity of the other reactants remains after the reaction has gone to completion. These other reactants are present in excess. An increase in the amount of the limiting reactant leads to an increase in the amount of product formed. This is not true of the other reactants. In an industrial process, the limiting reactant is often the most expensive one, to [Pg.41]

There is a systematic method to find the limiting reactant and determine the maximum possible amounts of products. Take each reactant in turn, assume that it is used up completely in the reaction, and calculate the mass of one of the products that will be formed. Whichever reactant gives the smallest mass of this product is the limiting reactant. Once it has reacted fully, no further product can be formed. [Pg.42]

Sulfuric acid (H2SO4) forms in the chemical reaction [Pg.42]

Suppose 400 g SO2, 175 g O2, and 125 g H2O are mixed and the reaction proceeds until one of the reactants is used up. Which is the limiting reactant. What mass of H2SO4 is produced, and what masses of the other reactants remain.  [Pg.42]


Determine the limiting reactant and the percentage yield for each of the following. [Pg.335]

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. [Pg.119]

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 ... [Pg.38]

In this chapter, you learned how to balance simple chemical equations by inspection. Then you examined the mass/mole/particle relationships. A mole has 6.022 x 1023 particles (Avogadro s number) and the mass of a substance expressed in grams. We can interpret the coefficients in the balanced chemical equation as a mole relationship as well as a particle one. Using these relationships, we can determine how much reactant is needed and how much product can be formed—the stoichiometry of the reaction. The limiting reactant is the one that is consumed completely it determines the amount of product formed. The percent yield gives an indication of the efficiency of the reaction. Mass data allows us to determine the percentage of each element in a compound and the empirical and molecular formulas. [Pg.44]

Assume that your friend has missed several chemistry classes and that she has asked you to help her prepare for a stoichiometry test. Unfortunately, because of other commitments, you do not have time to meet face to face. You agree to email your friend a set of point-form instructions on how to solve stoichiometry problems, including those that involve a limiting reactant. She also needs to understand the concept of percentage yield. Write the text of this email. Assume that your friend has a good understanding of the mole concept. [Pg.273]

When you have a given amount of one reactant and you decide the amount of a second reactant, which reactant should be the limiting reactant if you want to maximize your percentage yield ... [Pg.279]

Atom efficiency the percentage yield (molar flow of the desired product divided by the molar flow of the limiting reactant, taking into account the stoichiometry of the reaction) multiplied by the atom economy. It could be used to replace yield and A E. Eor example, AE could be 100% and yield 5%, making this a not very green reaction. [Pg.297]

In Examples 10.2 and 10.3, we determined the maximum amount of product that could be formed from the given amounts of reactants. This is the amount of product that could be obtained if 100% of the limiting reactant were converted to product and if this product could be isolated from the other components in the product mixture without any loss. This calculated maximum yield is called the theoretical yield. Often, somewhat less than 100% of the limiting reactant is converted to product, and somewhat less than the total amount of product is isolated from the mixture, so the actual yield of the reaction, the amount of product that one actually obtains, is less than the theoretical yield. The actual yield is sometimes called the experimental yield. The efficiency of a reaction can be evaluated by calculating the percent yield, the ratio of the actual yield to the theoretical yield expressed as a percentage. [Pg.382]

The amount of a product formed when the limiting reactant is completely consumed is called the theoretical yield of that product. In Example 3.17, 10.6 grams of nitrogen represents the theoretical yield. This is the maximum amount of nitrogen that can be produced from the quantities of reactants used. Actually, the amount of product predicted by the theoretical yield is seldom obtained because of side reactions (other reactions that involve one or more of the reactants or products) and other complications. The actual yield of product is often given as a percentage of the theoretical yield. This is called the pereent yield ... [Pg.113]

One reactant limits the product of a reaction. Comparing the actual and theoretical yields helps chemists determine the reaction s efficiency. j andP Key Terms limiting reactant Illy ncci ercenti theoretical yield ml wl,.vM lUICIIIId age Yield percentage yield... [Pg.296]

When you use stoichiometry to calculate the amount of product formed in a reaction, you are calculating the theoretical yield of the reaction. The theoretical yield is the amount of product that forms when all the limiting reactant reacts to form the desired product It is the maximum obtainable yield, predicted by the balanced equation. In practice, the actual yield— the amount of product actually obtained from a reaction—is almost always less than the theoretical yield. Th e are many reasons for the difference between the actual and theoretical yields. For instance, some of the reactants may not react to form the desired product. They may react to form different products, in something known as side reactions, or they may simply remain unreacted. In addition, it may be difficult to isolate and recover all the product at the end of the reaction. Chemists often determine the efficiency of a chemical reaction by calculating its percent yield, which tells what percentage the actual yield is of the theoretical yield. It is calculated as follows ... [Pg.96]


See other pages where Limiting Reactant and Percentage Yield is mentioned: [Pg.319]    [Pg.330]    [Pg.346]    [Pg.347]    [Pg.29]    [Pg.41]    [Pg.49]    [Pg.282]    [Pg.304]    [Pg.306]    [Pg.319]    [Pg.330]    [Pg.346]    [Pg.347]    [Pg.29]    [Pg.41]    [Pg.49]    [Pg.282]    [Pg.304]    [Pg.306]    [Pg.83]    [Pg.335]    [Pg.86]    [Pg.107]    [Pg.107]    [Pg.109]    [Pg.111]    [Pg.119]    [Pg.124]    [Pg.973]    [Pg.251]    [Pg.260]    [Pg.75]    [Pg.44]    [Pg.1147]    [Pg.102]    [Pg.332]    [Pg.525]   


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Limiting Reactant Theoretical and Percentage Yields

Percentage

Yield percentage

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