Zinc reacts with iodine in a synthesis reaction: Zn + I 2

Interpret the following balanced chemical equations in terms of particles, moles, and mass. Show that the law of conservation of mass is observed. a. N 2(g) + 3 H 2(g) 2N H 3(g) b. HCl(aq) + KOH(aq) KCl(aq) + H 2O(l) c. 2Mg(s) + O 2(g) 2MgO(s)

Challenge For each of the following, balance the chemical equation; interpret the equation in terms of particles, moles, and mass; and show that the law of conservation of mass is observed. a. ___Na(s) + ___ H 2O(l) ___NaOH(aq) + ___ H 2(g) b. ___Zn(s) + ___HN O 3(aq) ___Zn(N O 3) 2(aq) + ___ N 2O(g) + ___ H 2O(l)

Determine all possible mole ratios for the following balanced chemical equations. a. 4Al(s) + 3 O 2(g) 2A l 2O 3(s) b. 3Fe(s) + 4 H 2O(l) F e 3O 4(s) + 4 H 2(g) c. 2HgO(s) 2Hg(l) + O 2(g)

Challenge Balance the following equations, and determine the possible mole ratios. a. ZnO(s) + HCl(aq) ZnC l 2(aq) + H 2O(l) b. butane ( C 4H 10) + oxygen carbon dioxide + water

Compare the mass of the reactants and the mass of the products in a chemical reaction, and explain how these masses are related.

State how many mole ratios can be written for a chemical reaction involving three substances.

Categorize the ways in which a balanced chemical equation can be interpreted.

Apply The general form of a chemical reaction is xA + y B zAB. In the equation, A and B are elements, and x, y, and z are coefficients. State the mole ratios for this reaction.

Apply Hydrogen peroxide ( H 2 O 2 ) decomposes to produce water and oxygen. Write a balanced chemical equation for this reaction, and determine the possible mole ratios.

Model Write the mole ratios for the reaction of hydrogen gas and oxygen gas, 2 H 2 (g) + O 2 (g) 2 H 2 O. Make a sketch of six hydrogen molecules reacting with the correct number of oxygen molecules. Show the water molecules produced.

Methane and sulfur react to produce carbon disulfide (C S 2), a liquid often used in the production of cellophane. ___C H 4(g) + ___ S 8(s) ___C S 2(l) + ___ H 2S(g) a. Balance the equation. b. Calculate the moles of C S 2 produced when 1.50 mol S 8 is used. c. How many moles of H 2S is produced?

Challenge Sulfuric acid ( H 2S O 4) is formed when sulfur dioxide (S O 2) reacts with oxygen and water. a. Write the balanced chemical equation for the reaction. b. How many moles of H 2S O 4 is produced from 12.5 moles of S O 2? c. How many moles of O 2 are needed?

Sodium chloride is decomposed into the elements sodium and chlorine by means of electrical energy. How much chlorine gas, in grams, is obtained from the process diagrammed at right?

Challenge Titanium is a transition metal used in many alloys because it is extremely strong and lightweight. Titanium tetrachloride ( TiC l 4) is extracted from titanium oxide ( Ti O 2) using chlorine and coke (carbon). Ti O 2(s) + C(s) + 2C l 2(g) TiC l 4(s) + C O 2(g) a. What mass of C l 2 gas is needed to react with 1.25 mol of Ti O 2? b. What mass of C is needed to react with 1.25 mol of Ti O 2? c. What is the mass of all of the products formed by reaction with 1.25 mol of Ti O 2?

One of the reactions used to inflate automobile air bags involves sodium azide (Na N 3): 2Na N 3(s) 2Na(s) + 3 N 2(g). Determine the mass of N 2 produced from the decomposition of NaN 3 shown at right.

Challenge In the formation of acid rain, sulfur dioxide (S O 2) reacts with oxygen and water in the air to form sulfuric acid ( H 2S O 4). Write the balanced chemical equation for the reaction. If 2.50 g of S O 2 reacts with excess oxygen and water, how much H 2S O 4, in grams, is produced?

Explain why a balanced chemical equation is needed to solve a stoichiometric problem.

List the four steps used in solving stoichiometric problems.

Describe how a mole ratio is correctly expressed when it is used to solve a stoichiometric problem

Apply How can you determine the mass of liquid bromine (B r 2 ) needed to react completely with a given mass of magnesium?

Calculate Hydrogen reacts with excess nitrogen as follows: N 2 (g) + 3 H 2 (g) 2N H 3 (g) If 2.70 g of H 2 reacts, how many grams of N H 3 is formed?

Design a concept map for the following reaction. CaC O 3 (s) + 2HCl(aq) CaC l 2 (aq) + H 2 O(l) + C O 2 (g) The concept map should explain how to determine the mass of CaC l 2 produced from a given mass of HCl.

The reaction between solid sodium and iron(III) oxide is one in a series of reactions that inflates an automobile airbag: 6Na(s) + F e 2O 3(s) 3N a 2O(s) + 2Fe(s). If 100.0 g of Na and 100.0 g of F e 2O 3 are used in this reaction, determine the following. a. limiting reactant b. reactant in excess c. mass of solid iron produced d. mass of excess reactant that remains after the reaction is complete

Challenge Photosynthesis reactions in green plants use carbon dioxide and water to produce glucose ( C 6H 12O 6) and oxygen. A plant has 88.0 g of carbon dioxide and 64.0 g of water available for photosynthesis. a. Write the balanced chemical equation for the reaction. b. Determine the limiting reactant. c. Determine the excess reactant. d. Determine the mass in excess. e. Determine the mass of glucose produced.

Describe the reason why a reaction between two substances comes to an end

Identify the limiting and the excess reactant in each reaction. a. Wood burns in a campfire. b. Airborne sulfur reacts with the silver plating on a teapot to produce tarnish (silver sulfide). c. Baking powder in batter decomposes to produce carbon dioxide

Analyze Tetraphosphorus trisulphide ( P 4 S 3 ) is used in the match heads of some matches. It is produced in the reaction 8 P 4 + 3 S 8 8 P 4 S 3 . Determine which of the following statements are incorrect, and rewrite the incorrect statements to make them correct. a. 4 mol P 4 reacts with 1.5 mol S 8 to form 4 mol P 4 S 3 . b. Sulfur is the limiting reactant when 4 mol P 4 and 4 mol S 8 react. c. 6 mol P 4 reacts with 6 mol S 8 , forming 1320 g P 4 S 3

Aluminum hydroxide (Al(OH ) 3) is often present in antacids to neutralize stomach acid (HCl). The reaction occurs as follows: Al(OH ) 3(s) + 3HCl(aq) AlC l 3(aq) + 3 H 2O(l). If 14.0 g of Al(OH ) 3 is present in an antacid tablet, determine the theoretical yield of AlC l 3 produced when the tablet reacts with HCl.

Zinc reacts with iodine in a synthesis reaction: Zn + I 2 Zn I 2. a. Determine the theoretical yield if 1.912 mol of zinc is used. b. Determine the percent yield if 515.6 g of product is recovered.

Challenge When copper wire is placed into a silver nitrate solution (AgN O 3), silver crystals and copper(II) nitrate (Cu(N O 3) 2) solution form. a. Write the balanced chemical equation for the reaction. b. If a 20.0-g sample of copper is used, determine the theoretical yield of silver. c. If 60.0 g of silver is recovered from the reaction, determine the percent yield of the reaction.

Identify which type of yieldtheoretical yield, actual yield, or percent yieldis a measure of the efficiency of a chemical reaction.

List several reasons why the actual yield from a chemical reaction is not usually equal to the theoretical yield.

Explain how percent yield is calculated

Apply In an experiment, you combine 83.77 g of iron with an excess of sulfur and then heat the mixture to obtain iron(III) sulfide. 2Fe(s) + 3S(s) F e 2 S 3 (s) What is the theoretical yield, in grams, of iron(III) sulfide?

Calculate the percent yield of the reaction of magnesium with excess oxygen: 2Mg(s) + O 2 (g) 2MgO(s) Reaction Data Mass of empty crucible 35.67 g Mass of crucible and Mg 38.06 g Mass of crucible and MgO (after heating) 39.15 g

Why must a chemical equation be balanced before you can determine mole ratios?

What relationships can be determined from a balanced chemical equation?

Explain why mole ratios are central to stoichiometric calculations

What is the mole ratio that can convert from moles of A to moles of B?

Why are coefficients used in mole ratios instead of subscripts?

Explain how the conservation of mass allows you to interpret a balanced chemical equation in terms of mass.

When heated by a flame, ammonium dichromate decomposes, producing nitrogen gas, solid chromium(III) oxide, and water vapor. (N H 4 )2C r 2 O 7 N 2 + C r 2 O 3 + 4 H 2 O Write the mole ratios for this reaction that relate ammonium dichromate to the products.

Figure 11.10 depicts an equation with squares representing Element M and circles representing Element N. Write a balanced equation to represent the picture shown, using smallest whole-number ratios. Write mole ratios for this equation.

Interpret the following equation in terms of particles, moles, and mass. 4Al(s) + 3 O 2 (g) 2A l 2 O 3 (s)

Smelting When tin(IV) oxide is heated with carbon in a process called smelting, the element tin can be extracted. Sn O 2 (s) + 2C(s) Sn(l) + 2CO(g) Interpret the chemical equation in terms of particles, moles, and mass

When solid copper is added to nitric acid, copper(II) nitrate, nitrogen dioxide, and water are produced. Write the balanced chemical equation for the reaction. List six mole ratios for the reaction.

When hydrochloric acid solution reacts with lead(II) nitrate solution, lead(II) chloride precipitates and a solution of nitric acid is produced. a. Write the balanced chemical equation for the reaction. b. Interpret the equation in terms of molecules and formula units, moles, and mass.

When aluminum is mixed with iron(III) oxide, iron metal and aluminum oxide are produced, along with a large quantity of heat. What mole ratio would you use to determine moles of Fe if moles of F e 2 O 3 is known? F e 2 O 3 (s) + 2Al(s) 2Fe(s) + A l 2 O 3 (s) + heat

Solid silicon dioxide, often called silica, reacts with hydrofluoric acid (HF) solution to produce the gas silicon tetrafluoride and water. a. Write the balanced chemical equation for the reaction. b. List three mole ratios, and explain how you would use them in stoichiometric calculations.

Chrome The most important commercial ore of chromium is chromite (FeC r 2 O 4 ). One of the steps in the process used to extract chromium from the ore is the reaction of chromite with coke (carbon) to produce ferrochrome (FeC r 2 ). 2C(s) + FeC r 2 O 4 (s) FeC r 2 (s) + 2C O 2 (g) What mole ratio would you use to convert from moles of chromite to moles of ferrochrome?

Air Pollution The pollutant S O 2 is removed from the air by in a reaction that also involves calcium carbonate and oxygen. The products of this reaction are calcium sulfate and carbon dioxide. Determine the mole ratio you would use to convert moles of S O 2 to moles of CaS O 4 .

Two substances, W and X, react to form the products Y and Z. Table 11.2 shows the moles of the reactants and products involved when the reaction was carried out. Use the data to determine the coefficients that will balance the equation W + X Y + Z. Table 11.2 Reaction Data Moles of Reactants Moles of Products WXY Z 0.90 0.30 0.60 1.20

Antacids Magnesium hydroxide is an ingredient in some antacids. Antacids react with excess hydrochloric acid in the stomach to relieve indigestion. ___Mg(OH ) 2 + ___HCl ___ MgC l 2 + ___ H 2 O a. Balance the reaction of Mg (OH ) 2 with HCl. b. Write the mole ratio that would be used to determine the number of moles of MgC l 2 produced when HCl reacts with Mg(OH ) 2 .

What is the first step in all stoichiometric calculations?

What information does a balanced equation provide?

On what law is stoichometry based, and how do the calculations support this law?

How is molar mass used in some stoichiometric calculations?

What information must you have in order to calculate the mass of product formed in a chemical reaction?

Each box in Figure 11.11 represents the contents of a flask. One flask contains hydrogen sulfide, and the other contains oxygen. When the contents of the flasks are mixed, a reaction occurs and water vapor and sulfur are produced. In the figure, the red circles represent oxygen, the yellow circles represent sulfur, and blue circles represent hydrogen. a. Write the balanced chemical equation for the reaction. b. Using the same color code, sketch a representation of the flask after the reaction occurs.

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

Welding If 5.50 mol of calcium carbide (Ca C 2 ) reacts with an excess of water, how many moles of acetylene ( C 2 H 2 ), a gas used in welding, will be produced? Ca C 2 (s) + 2 H 2 O(l) Ca(OH ) 2 (aq) + C 2 H 2 (g)

Antacid Fizz When an antacid tablet dissolves in water, the fizz is due to a reaction between sodium hydrogen carbonate (NaHC O 3 ), also called sodium bicarbonate, and citric acid ( H 3 C 6 H 5 O 7 ). 3NaHC O 3 (aq) + H 3 C 6 H 5 O 7 (aq) 3C O 2 (g) + 3 H 2 O(l) + N a 3 C 6 H 5 O 7 (aq) How many moles of N a 3 C 6 H 5 O 7 can be produced if one tablet containing 0.0119 mol of NaHC O 3 is dissolved?

Esterification The process in which an organic acid and an alcohol react to form an ester and water is known as esterification. Ethyl butanoate ( C 3 H 7 COO C 2 H 5 ), an ester, is formed when the alcohol ethanol ( C 2 H 5 OH) and butanoic acid ( C 3 H 7 COOH) and are heated in the presence of sulfuric acid. C 2 H 5 OH(l) + C 3 H 7 COOH(l) C 3 H 7 COO C 2 H 5 (l) + H 2 O(l) Determine the mass of ethyl butanoate produced if 4.50 mol of ethanol is used.

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 ( C 8 H 18 ) in gasoline. Write the balanced chemical equation for the combustion of octane and calculate the mass of octane needed to release 5.00 mol of C O 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 ( N 2 H 2 ) and liquid hydrogen peroxide ( H 2 O 2 ) 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 (CHC l 3 ), an important solvent, is produced by a reaction between methane and chlorine. C H 4 (g) + 3C l 2 (g) CHC l 3 (g) + 3HCl(g) How much C H 4 , in grams, is needed to produce 50.0 grams of CHC l 3 ?

Oxygen Production The Russian Space Agency uses potassium superoxide (K O 2 ) for the chemical oxygen generators in their space suits. 4K O 2 + 2 H 2 O + 4C O 2 4KHC O 3 + 3 O 2 Complete Table 11.3. Table 11.3 Oxygen Generation Reaction Data Mass K O 2 Mass H 2O Mass C O 2 Mass KHC O 3 Mass O 2 380 g

Gasohol is a mixture of ethanol and gasoline. Balance the equation, and determine the mass of C O 2 produced from the combustion of 100.0 g of ethanol. C 2 H 5 OH(l) + O 2 (g) C O 2 (g) + H 2 O(g)

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. 4Au(s) + 8NaCN(aq) + O 2 (g) + 2 H 2 O(l) 4NaAu(CN ) 2 (aq) + 4NaOH(aq) a. Determine the mass of gold that can be extracted if 25.0 g of sodium cyanide is used. b. If the mass of the ore from which the gold was extracted is 150.0 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 (N a 3 Ag( S 2 O 3 ) 2 ) is produced. AgBr(s) + 2N a 2 S 2 O 3 (aq) N a 3 Ag( S 2 O 3 ) 2 (aq) + NaBr(aq) Determine the mass of N a 3 Ag( S 2 O 3 ) 2 produced if 0.275 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.

Figure 11.12 uses squares to represent Element M and circles to represent Element N. a. Write the balanced equation for the reaction. b. If each square represents 1 mol of M and each circle represents 1 mol of N, how many moles of M and N were present at the start of the reaction? c. How many moles of product form? How many moles of Element M and Element N are unreacted? d. Identify the limiting reactant and the excess reactant.

The reaction between ethyne ( C 2 H 2 ) and hydrogen ( H 2 ) is illustrated in Figure 11.13. The product is ethane ( C 2 H 6 ). Which is the limiting reactant? Which is the excess reactant? Explain.

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

One of the few xenon compounds that form is cesium xenon heptafluoride (CsXe F 7 ). How many moles of CsXe F 7 can be produced from the reaction of 12.5 mol of cesium fluoride with 10.0 mol of xenon hexafluoride? CsF(s) + Xe F 6 (s) CsXe F 7 (s)

Iron Production Iron is obtained commercially by the reaction of hematite (F e 2 O 3 ) with carbon monoxide. How many grams of iron is produced when 25.0 mol of hematite reacts with 30.0 mol of carbon monoxide? F e 2 O 3 (s) + 3CO(g) 2Fe(s) + 3C O 2 (g)

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

Alkaline Battery An alkaline battery produces electrical energy according to this equation. Zn(s) + 2Mn O 2 (s) + H 2 O(l) Zn(OH ) 2 (s) + M n 2 O 3 (s) a. Determine the limiting reactant if 25.0 g of Zn and 30.0 g of Mn O 2 are used. b. Determine the mass of Zn(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?

Examine the reaction represented in Figure 11.14. Determine if the reaction went to completion. Explain your answer, and calculate the percent yield of the reaction.

Ethanol ( C 2 H 5 OH) is produced from the fermentation of sucrose ( C 12 H 22 O 11 ) in the presence of enzymes. C 12 H 22 O 11 (aq) + H 2 O(g) 4 C 2 H 5 OH(l) + 4C O 2 (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: PbS(s) + O 2 (g) PbO(s) + S O 2 (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 (CaC O 3 ) decomposes to calcium oxide (CaO) and carbon dioxide (C O 2 ). a. Determine the theoretical yield of C O 2 if 235.0 g of CaC O 3 is heated. b. What is the percent yield of C O 2 if 97.5 g of C O 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 ( H 2 Si F 6 ). Si O 2 (s) + 6HF(aq) H 2 Si F 6 (aq) + 2 H 2 O(l) 40.0 g Si O 2 and 40.0 g HF react to yield 45.8 g H 2 Si F 6 . a. What is the limiting reactant? b. What is the mass of the excess reactant? c. What is the theoretical yield of H 2 Si F 6 ? d. What is the percent yield?

Van Arkel Process Pure zirconium is obtained using the two-step Van Arkel process. In the first step, impure zirconium and iodine are heated to produce zirconium iodide (Zr I 4 ). In the second step, Zr I 4 is decomposed to produce pure zirconium. Zr I 4 (s) Zr(s) + 2 I 2 (g) Determine the percent yield of zirconium if 45.0 g of Zr I 4 is decomposed and 5.00 g of pure Zr is obtained.

Methanol, wood alcohol, is produced when carbon monoxide reacts with hydrogen gas. CO + 2 H 2 C H 3 OH When 8.50 g of carbon monoxide reacts with an excess of hydrogen, 8.52 g of methanol is collected. Complete Table 11.4, and calculate the percent yield. Table 11.4 Methanol Reaction Data CO(g) C H 3OH(l) Mass 8.52 g Molar mass 28.01 g/mol 32.05 g/mol Moles

Phosphorus ( P 4 ) is commercially prepared by heating a mixture of calcium phosphate (CaSi O 3 ), sand (Si O 2 ), and coke (C) in an electric furnace. The process involves two reactions. 2C a 3 (P O 4 ) 2 (s) + 6Si O 2 (s) 6CaSi O 3 (l) + P 4 O 10 (g) P 4 O 10 (g) + 10C(s) P 4 (g) + 10CO(g) The P 4 O 10 produced in the first reaction reacts with an excess of coke (C) in the second reaction. Determine the theoretical yield of P 4 if 250.0 g of C a 3 (P O 4 ) 2 and 400.0 g of Si O 2 are heated. If the actual yield of P 4 is 45.0 g, determine the percent yield of P 4

Chlorine forms from the reaction of hydrochloric acid with manganese(IV) oxide. The balanced equation is: Mn O 2 + 4HCl MnC l 2 + C l 2 + 2 H 2 O Calculate the theoretical yield and the percent yield of chlorine if 86.0 g of Mn O 2 and 50.0 g of HCl react. The actual yield of C l 2 is 20.0 g.

Ammonium sulfide reacts with copper(II) nitrate in a double replacement reaction. What mole ratio would you use to determine the moles of N H 4 N O 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. Ca C 2 (s) + N 2 (g) CaNCN(s) + C(s) What mass of CaNCN can be produced if 7.50 mol of Ca C 2 reacts with 5.00 mol of 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

Iron reacts with oxygen as shown. 4Fe(s) + 3 O 2 (g) 2F e 2 O 3 (s) Different amounts of iron were burned in a fixed amount of oxygen. For each mass of iron burned, the mass of iron(II) oxide formed was plotted on the graph shown in Figure 11.15. Why does the graph level off after 25.0 g of iron is burned? How many moles of oxygen are present in the fixed amount?

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.

Apply Students conducted a lab to investigate limiting and excess reactants. The students added different volumes of sodium phosphate solution (N a 3 P O 4 ) to a beaker. They then added a constant volume of cobalt(II) nitrate solution (Co(N O 3 ) 2 ), stirred the contents, and allowed the beakers to sit overnight. The next day, each beaker had a purple precipitate at the bottom. The students decanted the supernatant from each beaker, divided it into two samples, and added one drop of sodium phosphate solution to one sample and one drop of cobalt(II) nitrate solution to the second sample. Their results are shown in Table 11.5. a. Write a balanced chemical equation for the reaction. b. Based on the results, identify the limiting reactant and the excess reactant for each trial. Table 11.5 Reaction Data for Co(N O 3) 2 and N a 3P O 4 Trial Volume N a 3P O 4 Volume Co(N O 3) 2 Reaction with Drop of N a 3P O 4 Reaction with Drop of Co(N O 3) 2 1 5.0 mL 10.0 mL purple precipitate no reaction 2 10.0 mL 10.0 mL no reaction purple precipitate 3 15.0 mL 10.0 mL no reaction purple precipitate 4 20.0 mL 10.0 mL no reaction purple precipitate

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 U F 6 ? What is the molar mass of U F 6 ? (Chapter 10)

Figure 11.16 gives percent composition data for several organic compounds. (Chapter 10) a. How are the molecular and empirical formulas of acetaldehyde and butanoic acid related? b. What is the empirical formula of butanoic acid?

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.

Balance the equation in Figure 11.17. If the bombardier beetle stores 100.0 mg of hydroquinone ( C 6 H 4 (OH ) 2 ) along with 50.0 mg of hydrogen peroxide ( H 2 O 2 ), what is the limiting reactant?

What is the excess reactant and how many milligrams are in excess?

How many milligrams of benzoquinone will be produced?