Chemical equations yield

The mole concept, when applied to chemical equations, yields relationships that can be used to obtain factors for doing factor-unit calculations. 

An examination of these chemical equations yields information concerning (1) the weights of materials that react and (2) the volumes of gases that react. For example, reaction 1 indicates that 1 cu ft of hydrogen reacts with one-half of 1 cu ft of oxygen to produce 1 cu ft of water vapor. Likewise reaction 6 shows that one volume. of methane requires... 

In order to obtain an improved yield of the desired product, an excess over the proportion required by the chemical equation of one (or more) of the reactants is often used. In a given preparation, the selection of the reagent to be employed in excess will depend upon a number of factors these include its relative cost and ease of removal after the reaction, and... 

By carrying out the reaction at —78°C it is possible to fluonnate 2 2 dimethylpropane to yield (CF3)4C Write a balanced chemical equation for this reaction... 

Potassium Nitrate. Potassium nitrate [7757-79-17, KNO, is produced commercially in the United States based on the reaction of potassium chloride and nitric acid (qv) (35). Ammonia (qv) oxidation is the source for the nitric acid and the reaction is manipulated chemically to yield chlorine as a co-product. The process is operated at an elevated temperature to drive the reaction to completion according to the following equation ... 

This is the relaxation time of the polymer oxidation under electro-chemically stimulated conformational relaxation control. So features concerning both electrochemistry and polymer science are integrated in a single equation defining a temporal magnitude for electrochemical oxidation as a function of the energetic terms acting on this oxidation. A theoretical development similar to the one performed for the Butler-Volmer equation yields... 

P, with the remainder oxygen. The mass spectrum of compound B yields a molar mass of 97.99 g-mol. Write the molecular formula of compound B. (c) Compound B reacts with an aqueous solution of calcium hydroxide to form compound C, a white precipitate. Write balanced chemical equations for the reactions in parts (a), (b), and (c). 

L.25 Barium bromide, BaBrv, can be converted into BaCl2 by treatment with chlorine. It is found that 3.25 g of BaBrv reacts completely with an excess of chlorine to yield 2.27 g of BaCl2. Determine the value of x and write the balanced chemical equation for the production of BaCl2 from BaBr,.. 

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%. 

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. 

C04-0041. Several examples of chemical reasoning are introduced in this chapter. Write out the reasoning steps that you will follow in (a) balancing a chemical equation (b) identifying the limiting reactant (c) determining whether a precipitate forms and (d) computing a reaction yield. 

Tropinone is another classic compound in the history of total synthesis. The celebrated plans of Willstatter and Robinson are shown in Schemes 4.20 and 4.21 and Figure 4.63 shows a synthesis map for different ways this compoimd has been made. The synthesis tree for the three-component Robinson plan is shown in Figure 4.64. Calcium carbonate and hydrochloric acid are added as inputs to complete the balanced chemical equation since these are involved in a neutralization reaction. It is clear from the results summarized in Table 4.30 that the Robinson plan is the clear front-rimner because the synthesis is achieved in a single step even though the reaction yield is modest. Any further improvements to this method would be directed to improving this parameter. 

Equation (3.1.2) and the definition of the chemical potential yield the equation for the electrochemical potential of species i with activity a,(j3) and charge z, in phase )8 in the form... 

Write balanced chemical equations for the following reactions (a) Hydrogen fluoride is produced by the reaction of hydrochloric acid and sodium fluoride. (b) Hydrochloric acid combines with sodium fluoride to yield hydrogen fluoride, (c) Sodium fluoride reacts with hydrochloric acid to give hydrofluoric acid. 

The percent yield is 100 times the amount of a product actually prepared during a reaction divided by the amount theoretically possible to be prepared according to the balanced chemical equation. (Some reactions are slow, and sometimes not enough time is allowed for their completion some reactions are accompanied by side reactions which consume a portion of the reactants some reactions never get to completion.) If 3.00g C6H,Br is prepared by treating 3.00g ChHl2 with excess Br2, what is the percent yield The equation is... 

The net ionic equation, like all balanced chemical equations, gives the ratio of moles of each substance to moles of each of the others. It does not immediately yield information about the mass of the entire salt, however. (One cannot weigh out only Ba2+ ions.) Therefore, when masses of reactants are required, the specific compound used must be included in the calculation. The use of net ionic equations in stoichiometric calculations will be more important after study of molarity (Chap. 10). 

A complex reaction requires more than one chemical equation and rate law for its stoichiometric and kinetics description, respectively. It can be thought of as yielding more than one set of products. The mechanisms for their production may involve some of the same intermediate species. In these cases, their rates of formation are coupled, as reflected in the predicted rate laws. 

Only 15 was sufficiently stable for isolation and chemical and structural characterization (33). Compounds 12-13 persist for several hours in chloroform at room temperature and for 2-3 weeks at 251K, particularly when water is carefully excluded. All three react readily with PR3, forming oxorhenium(V) compounds that in these cases, unlike those with dithiolates, are metastable. The fastest reaction occurs between P(p-MeOC6H4)3 and 13, with a rate constant of 2.15 x 102Lmol 1s 1 in chloroform at 298 K. Other reactions of PAr3 upon applying the Hammett equation yield p =— 0.7. This is the same value of the reaction... 

Step 2 Write a balanced chemical equation that describes the reaction, silver + chlorine gas yields silver chloride. 

It is possible to consider a balanced chemical equation, such as this one, on many levels. One of these levels is the mole level. At this level, we can get the moles just by reading the equation in terms of moles. 1 mol of H2 plus 1 mol of Cl2 yields 2 mol of hydrogen chloride. 

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. 

In this case, as in all others, a calculation should be made at the conclusion of the experiment of the percentage of the theoretical yield which has been obtained, keeping in mind the following considerations. According to the chemical equation one mole of alcohol (46) should be used for one mole of potassium bromide (119). Actually, however, in the case of organic reactions, which as a rule do not proceed quantitatively, one of the components is used in excess, in keeping with the law of mass action (pp. 142,143), and its choice is often determined by economic considerations. Thus, for example, 1 kg. of potassium bromide costs about 6s., and 1 kg. of duty-free alcohol, Is. 2d. The price of a mole of KBr (119 x 6s.) is therefore to that of a mole of alcohol (95 per cent) (46 x Is. 2d.) approximately as 14 1. From the economic standpoint it is therefore advisable to use the cheaper alcohol in excess in order that as much as possible of the dearer bromine compound may be con-... 

Michael, interested in the hypothesis of the polymolecule and transition forms, was one of the first chemists to recognize clearly that some reactions are under kinetic control, yielding initially the thermodynamically less stable product. Modern kineticists concern themselves not only with the reactants and products that appear in the straightforward chemical equation but with intermediate steps in the reaction and with factors such as concentration, temperature, solvent, and catalyst which determine the rate.50... 

The potential of these reactions for methane production can be compared in terms of theoretical yields and heat recovery efficiencies. Theoretical methane yield is defined by the chemical equations. Theoretical heat recovery efficiency is defined as the percent of the higher heating value of the coal which is recovered in the form of methane product. These idealized parameters provide a measure of the ultimate capability of conversion systems and are useful for evaluating actual conversion processes. 

Which reactant is the limiting reactant How does the experimental mole ratio of Fe to Cu compare with the mole ratio in the balanced chemical equation What is the percent yield ... 

Evaluating Results Use the balanced chemical equation to calculate the mass of copper that should have been produced from the sample of iron you used. Use this number and the mass of copper you actually obtained to calculate the percent yield. 

The reaction of calcium carbide with water yields two products. One is ethyne gas (C2H2). From your observation in step 6, suggest what the other product is, and write a balanced chemical equation for the reaction. 

Having a balanced chemical equation and knowing the relationship between mass and moles allows us to predict how much reactant is necessary to yield a certain amount of product. This knowledge has important applications in industrial chemistry, environmental chemistry, nutrition, and in any situation where reactions take place. The balanced equation is a recipe for a chemical reaction. Just as it is necessary to know the amount of eggs, flour, sugar, and salt to bake a cake, we need to know the amount of ingredients that go into a chemical reaction. The balanced chemical equation gives the quantities of different reactants that are required to produce a specific amount of product. 

Many conditions are required for a chemical reaction to proceed. Conditions such as heat, light, and pressure must be just right for a reaction to take place. Furthermore, the reaction may proceed very slowly. Some reactions occur in a fraction of a second, while others occur very slowly. Consider the difference in the reaction times of gasoline igniting in a car s cylinder versus the oxidation of iron to form rust. The area of chemistry that deals with how fast reactions occur is known as kinetics (Chapter 12). Finally, not all reactions go to completion. The amount of product produced based on the chemical equation is known as the theoretical yield. The amount actually obtained expressed as a percent of the theoretical is the actual yield. In summary, it s best to think of a chemical equation as an ideal representation of a reaction. The equation provides a general picture of the reaction and enables us to do theoretical calculations, but in reality reactions deviate in many ways from that predicted by the equation. 

Each system considered in this section has a space of overall reactions whose dimension exceeds one. In many industrial reactions involving organic substances a major product is formed, but a side reaction contributes to loss in selectivity or yield of the desired product. Such cases may be said to exhibit a multiple overall reaction, unless the ratio of desired product to by-product remains constant over a range of operating conditions, so that a simple chemical equation might be employed to express the stoichiometry. 

Problem 15.58 Translate the following description into a chemical equation Friedel-Crafts acylation of resorcinol( 1,3-dihydroxybenzene) with CH,(CH2)4COCI produces a compound which on Clemmensen reduction yields the important antiseptic, hexylresorcinol. 

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