Chapter 11

Ethanol \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)\) also known as grain alcohol, can be made from the fermentation of sugar \(\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)\) The unbalanced chemical equation for the reaction is shown below. ___ \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} \rightarrow\) ___ \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}+\)___ \(\mathrm{CO}_{2}\) Balance the chemical equation and determine the mass of \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) produced from 750 \(\mathrm{g}\) of \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\)

Welding If 5.50 mol of calcium carbide \(\left(\mathrm{CaC}_{2}\right)\) reacts with an excess of water, how many moles of acetylene \(\left(\mathrm{C}_{2} \mathrm{H}_{2}\right),\) a gas used in welding, will be produced? $$\mathrm{CaC}_{2}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})+\mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{g})$$

Antacid Fizz When an antacid tablet dissolves in water, the fizz is due to a reaction between sodium hydrogen carbonate \(\left(\mathrm{NaHCO}_{3}\right)\) also called sodium bicarbonate, and citric acid \(\left(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right)\) $$\begin{array}{l}{3 \mathrm{NaHCO}_{3}(\mathrm{aq})+\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq}) \rightarrow} \\ {3 \mathrm{CO}_{2}(\mathrm{g})+3 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}(\mathrm{aq})}\end{array}$$ How many moles of \(\mathrm{Na}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\) can be produced if one tablet containing 0.0119 \(\mathrm{mol}\) of \(\mathrm{NaHCO}_{3}\) is dissolved?

Greenhouse Gas Carbon dioxide is a greenhouse gas that is linked to global warming. It is released into the atmosphere through the combustion of octane \(\left(\mathrm{C}_{8} \mathrm{H}_{18}\right)\) in gasoline. Write the balanced chemical equation for the combustion of octane and calculate the mass of octane needed to release 5.00 \(\mathrm{mol}\) of \(\mathrm{CO}_{2}\)

A solution of potassium chromate reacts with a solution of lead(II) nitrate to produce a yellow precipitate of lead(II) chromate and a solution of potassium nitrate. a. Write the balanced chemical equation. b. Starting with 0.250 mol of potassium chromate, determine the mass of lead chromate formed.

Rocket Fuel The exothermic reaction between liquid hydrazine \(\left(\mathrm{N}_{2} \mathrm{H}_{2}\right)\) and liquid hydrogen peroxide \(\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)\) is used to fuel rockets. The products of this reaction are nitrogen gas and water. a. Write the balanced chemical equation. b. How much hydrazine, in grams, is needed to produce 10.0 mol of nitrogen gas?

Chloroform \(\left(\mathrm{CHCl}_{3}\right),\) an important solvent, is produced by a reaction between methane and chlorine. $$\mathrm{CH}_{4}(\mathrm{g})+3 \mathrm{Cl}_{2}(\mathrm{g}) \rightarrow \mathrm{CHCl}_{3}(\mathrm{g})+3 \mathrm{HCl}(\mathrm{g})$$ How much \(\mathrm{CH}_{4},\) in grams, is needed to produce 50.0 \(\mathrm{grams}\) of \(\mathrm{CHCl}_{3} ?\)

Oxygen Production The Russian Space Agency uses potassium superoxide \(\left(\mathrm{KO}_{2}\right)\) for the chemical oxygen generators in their space suits. $$4 \mathrm{KO}_{2}+2 \mathrm{H}_{2} \mathrm{O}+4 \mathrm{CO}_{2} \rightarrow 4 \mathrm{KHCO}_{3}+3 \mathrm{O}_{2}$$

Car Battery Car batteries use lead, lead(IV) oxide, and a sulfuric acid solution to produce an electric current. The products of the reaction are lead(II) sulfate in solution and water. a. Write the balanced equation for the reaction. b. Determine the mass of lead(II) sulfate produced when 25.0 g of lead reacts with an excess of lead(IV) oxide and sulfuric acid.

To extract gold from its ore, the ore is treated with sodium cyanide solution in the presence of oxygen and water. \(4 \mathrm{Au}(\mathrm{s})+8 \mathrm{NaCN}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{g})+2 \mathrm{H}_{2} \mathrm{O}(1) \rightarrow\) \(4 \mathrm{NaAu}(\mathrm{CN})_{2}(\mathrm{aq})+4 \mathrm{NaOH}(\mathrm{aq})\) a. Determine the mass of gold that can be extracted if 25.0 \(\mathrm{g}\) of sodium cyanide is used. b. If the mass of the ore from which the gold was extracted is \(150.0 \mathrm{g},\) what percentage of the ore is gold?

Film Photographic film contains silver bromide in gelatin. Once exposed, some of the silver bromide decomposes, producing fine grains of silver. The unexposed silver bromide is removed by treating the film with sodium thiosulfate. Soluble sodium silver thiosulfate \(\left(\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}\right)\) is produced. \(\mathrm{AgBr}(\mathrm{s})+2 \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}(\mathrm{aq}) \rightarrow\) \(\mathrm{Na}_{3} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NaBr}(\mathrm{aq})\) Determine the mass of Nas Ag(S_ \(_{2} \mathrm{O}_{3} )_{2}\) produced if 0.275 \(\mathrm{g}\) of AgBr is removed.

How is a mole ratio used to find the limiting reactant?

Explain why the statement, “The limiting reactant is the reactant with the lowest mass” is incorrect.

Nickel-Iron Battery In \(1901,\) Thomas Edison inventt the nickel-iron battery. The following reaction takes place in the battery. $$\mathrm{Fe}(\mathrm{s})+2 \mathrm{NiO}(\mathrm{OH})(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow\( \)\mathrm{Fe}(\mathrm{OH})_{2}(\mathrm{s})+2 \mathrm{Ni}(\mathrm{OH})_{2}(\mathrm{aq})$$ How many mol of Fe(OH), is produced when 5.00 \(\mathrm{mol}\) of Fe and 8.00 \(\mathrm{mol}\) of \(\mathrm{NiO}(\mathrm{OH})\) react?

One of the few xenon compounds that form is cesium xenon heptafluoride (CsXeF \(_{7} ) .\) How many moles of CsXeF \(_{7}\) can be produced from the reaction of 12.5 \(\mathrm{mol}\) of cesium fluoride with 10.0 \(\mathrm{mol}\) of xenon hexafluoride? $$\mathrm{CsF}(\mathrm{s})+\mathrm{XeF}_{6}(\mathrm{s}) \rightarrow \mathrm{Cs} \mathrm{XeF}_{7}(\mathrm{s})$$

Iron Production Iron is obtained commercially by the reaction of hematite \(\left(\mathrm{Fe}_{2} \mathrm{O}_{3}\right)\) with carbon monoxide. How many grams of iron is produced when 25.0 \(\mathrm{mol}\) of hematite reacts with 30.0 \(\mathrm{mol}\) of carbon monoxide? $$\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+3 \mathrm{CO}(\mathrm{g}) \rightarrow 2 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_{2}(\mathrm{g})$$

The reaction of chlorine gas with solid phosphorus \(\left(\mathrm{P}_{4}\right)\) produces solid phosphorus pentachloride. When 16.0 \(\mathrm{g}\) of chlorine reacts with 23.0 \(\mathrm{g}\) of \(\mathrm{P}_{4},\) which reactant is limiting? Which reactant is in excess?

Alkaline Battery An alkaline battery produces electrical energy according to this equation. $$\mathrm{Zn}(\mathrm{s})+2 \mathrm{MnO}_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow$$ $$\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{Mn}_{2} \mathrm{O}_{3}(\mathrm{s})$$ a. Determine the limiting reactant if 25.0 \(\mathrm{g}\) of \(\mathrm{Zn}\) and 30.0 \(\mathrm{g}\) of \(\mathrm{MnO}_{2}\) are used. b. Determine the mass of \(\mathrm{Zn}(\mathrm{OH})_{2}\) produced.

Lithium reacts spontaneously with bromine to produce lithium bromide. Write the balanced chemical equation for the reaction. If 25.0 g of lithium and 25.0 g of bromine are present at the beginning of the reaction, determine a. the limiting reactant. b. the mass of lithium bromide produced. c. the excess reactant and the excess mass.

What is the difference between actual yield and theoretical yield?

How are actual yield and theoretical yield determined?

Can the percent yield of a chemical reaction be more than 100\(\% ?\) Explain your answer.

What relationship is used to determine the percent yield of a chemical reaction?

What experimental information do you need in order to calculate both the theoretical and the percent yield of any chemical reaction?

A metal oxide reacts with water to produce a metal hydroxide. What additional information would you need to determine the percent yield of metal hydroxide from this reaction?

Ethanol \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)\) is produced from the fermentation of sucrose \(\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)\) in the presence of enzymes. $$\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightarrow 4 \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{l})+4 \mathrm{CO}_{2}(\mathrm{g})$$ Determine the theoretical yield and the percent yield of ethanol if 684 g of sucrose undergoes fermentation and 349 g of ethanol is obtained.

Lead(II) oxide is obtained by roasting galena, lead(II) sulfide, in air. The unbalanced equation is: $$\mathrm{PbS}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{PbO}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g})$$ a. Balance the equation, and determine the theoretical yield of PbO if 200.0 g of PbS is heated. b. What is the percent yield if 170.0 g of PbO is obtained?

Upon heating, calcium carbonate \(\left(\mathrm{CaCO}_{3}\right)\) decomposes to calcium oxide \((\mathrm{CaO})\) and carbon dioxide \(\left(\mathrm{CO}_{2}\right)\) a. Determine the theoretical yield of \(\mathrm{CO}_{2}\) if 235.0 \(\mathrm{g}\) of \(\mathrm{CaCO}_{3}\) is heated. b. What is the percent yield of \(\mathrm{CO}_{2}\) if 97.5 \(\mathrm{g}\) of \(\mathrm{CO}_{2}\) is collected?

Hydrofluoric acid solutions cannot be stored in glass containers because HF reacts readily with silica dioxide in glass to produce hexafluorosilicic acid ( \(\mathrm{H}_{2} \mathrm{SiF}_{6}\) ). $$\mathrm{SiO}_{2}(\mathrm{~s})+6 \mathrm{HF}(\mathrm{aq}) \rightarrow \mathrm{H}_{2} \mathrm{SiF}_{6}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})$$ \(40.0 \mathrm{~g} \mathrm{SiO}_{2}\) and \(40.0 \mathrm{~g} \mathrm{HF}\) react to yield \(45.8 \mathrm{~g} \mathrm{H}_{2} \mathrm{SiF}_{6}\) a. What is the limiting reactant? b. What is the mass of the excess reactant? c. What is the theoretical yield of \(\mathrm{H}_{2} \mathrm{SiF}_{6} ?\) d. What is the percent yield?

Phosphorus \(\left(P_{4}\right)\) is commercially prepared by heating a mixture of calcium phosphate (CaSiO \(_{3} ),\) sand \(\left(\mathrm{SiO}_{2}\right)\) and coke (C) in an electric furnace. The process involves two reactions. $$ \begin{array}{c}{2 \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}(\mathrm{s})+6 \mathrm{SiO}_{2}(\mathrm{s}) \rightarrow 6 \mathrm{CaSiO}_{3}(1)+\mathrm{P}_{4} \mathrm{O}_{10}(\mathrm{g})} \\\ {\mathrm{P}_{4} \mathrm{O}_{10}(\mathrm{g})+10 \mathrm{C}(\mathrm{s}) \rightarrow \mathrm{P}_{4}(\mathrm{g})+10 \mathrm{CO}(\mathrm{g})}\end{array} $$ The \(\mathrm{P}_{4} \mathrm{O}_{10}\) produced in the first reaction reacts with an excess of coke (C) in the second reaction. Determine the theoretical yield of \(\mathrm{P}_{4}\) if 250.0 \(\mathrm{g}\) of \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) and 400.0 \(\mathrm{g}\) of \(\mathrm{SiO}_{2}\) are heated. If the actual yield of \(\mathrm{P}_{4}\) is 45.0 \(\mathrm{g}\) , determine the percent yield of \(\mathrm{P}_{4}\) .

Chlorine forms from the reaction of hydrochloric acid with manganese(IV) oxide. The balanced equation is: $$\mathrm{MnO}_{2}+4 \mathrm{HCl} \rightarrow \mathrm{MnCl}_{2}+\mathrm{Cl}_{2}+2 \mathrm{H}_{2} \mathrm{O}$$ Calculate the theoretical yield and the percent yield of chlorine if 86.0 \(\mathrm{g}\) of \(\mathrm{MnO}_{2}\) and 50.0 \(\mathrm{g}\) of HCl react. The actual yield of \(\mathrm{Cl}_{2}\) is 20.0 \(\mathrm{g}\)

Ammonium sulfide reacts with copper(II) nitrate in a double replacement reaction. What mole ratio would you use to determine the moles of \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) produced if the moles of CuS are known?

Fertilizer The compound calcium cyanamide (CaNCN) is used as a nitrogen source for crops. To obtain this compound, calcium carbide is reacted with nitrogen at high temperatures. $$ \mathrm{CaC}_{2}(\mathrm{s})+\mathrm{N}_{2}(\mathrm{g}) \rightarrow \mathrm{CaNCN}(\mathrm{s})+\mathrm{C}(\mathrm{s}) $$ What mass of CaNCN can be produced if 7.50 \(\mathrm{mol}\) of \(\mathrm{CaC}_{2}\) reacts with 5.00 \(\mathrm{mof} \mathrm{N}_{2} ?\)

When copper(II) oxide is heated in the presence of hydrogen gas, elemental copper and water are produced. What mass of copper can be obtained if 32.0 g of copper(II) oxide is used?

Air Pollution Nitrogen oxide, which is present in urban air pollution, immediately converts to nitrogen dioxide as it reacts with oxygen. a. Write the balanced chemical equation for the formation of nitrogen dioxide from nitrogen oxide. b. What mole ratio would you use to convert from moles of nitrogen oxide to moles of nitrogen dioxide?

Electrolysis Determine the theoretical and percent yield of hydrogen gas if 36.0 g of water undergoes electrolysis to produce hydrogen and oxygen and 3.80 g of hydrogen is collected.

Analyze and Conclude In an experiment, you obtain a percent yield of product of 108\(\% .\) Is such a percent yield possible? Explain. Assuming that your calculation is correct, what reasons might explain such a result?

Observe and Infer Determine whether each reaction depends on a limiting reactant. Explain why or why not, and identify the limiting reactant. a. Potassium chlorate decomposes to form potassium chloride and oxygen. b. Silver nitrate and hydrochloric acid react to produce silver chloride and nitric acid.

Design an Experiment Design an experiment that can be used to determine the percent yield of anhydrous copper(II) sulfate when copper(II) sulfate pentahydrate is heated to remove water.

Apply When a campfire begins to die down and smolder, you can rekindle the flame by fanning the fire. Explain, in terms of stoichiometry, why the fire again begins to flare up when fanned.

When 9.59 g of a certain vanadium oxide is heated in the presence of hydrogen, water and a new oxide of vanadium are formed. This new vanadium oxide has a mass of 8.76 g. When the second vanadium oxide undergoes additional heating in the presence of hydrogen, 5.38 g of vanadium metal forms. a. Determine the empirical formulas for the two vanadium oxides. b. Write balanced equations for the steps of the reaction. c. Determine the mass of hydrogen needed to complete the steps of this reaction.

You observe that sugar dissolves more quickly in hot tea than in iced tea. You state that higher temperatures increase the rate at which sugar dissolves in water. Is this statement a hypothesis or a theory? Why? (Chapter 1)

Write the electron configuration for each of the following atoms. (Chapter 5) a. fluorine c. titanium b. aluminum d. radon

Explain why the gaseous nonmetals exist as diatomic molecules, but other gaseous elements exist as single atoms. (Chapter 8)

Write a balanced equation for the reaction of potassium with oxygen. (Chapter 9)

What is the molecular mass of \(\mathrm{UF}_{6}\) ? What is the molar mass of \(\mathrm{UF}_{6}\) ? (Chapter 10\()\)

Air Pollution Research the air pollutants produced by combustion of gasoline in internal combustion engines. Discuss the common pollutants and the reaction that produces them. Show, through the use of stoichiometry, how each pollutant could be reduced if more people used mass transit.

Haber Process The percent yield of ammonia produced when hydrogen and nitrogen are combined under ordinary conditions is extremely small. However, the Haber Process combines the two gases under a set of conditions designed to maximize yield. Research the conditions used in the Haber Process, and find out why the development of the process was of great importance.