StoichiometryStoichiometry - Weebly

1 Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Manual chemistry : Matter and Change Chapter 11 209 StoichiometryStoichiometrySOLUTIONS MANUALCHAPTER11 Section Defining Stoichiometrypages 368 372 Practice Problemspages 371 372 1. Interpret the following balanced chemical equa-tions in terms of particles, moles, and mass. Show that the law of conservation of mass is N2(g) 3H2(g) 2NH3(g)1 molecule N2 3 moleculesH2 2 molecules NH31 mole N2 3 moles H2 2 moles NH3 Mass:N2: (2 mol)( g/mol) g3H2: (6 mol)( g/mol) g2NH3: (2 mol)( g/mol) (6 mol)( g/mol) g N2 g H2 0 g g reactants g productsb. HCl(aq) KOH(aq) KCl(aq) H2O(l)1 molecule HCl 1 formula unit KOH 1 formula unit KCl 1 molecule H2O1 mole HCl 1 mole KOH 1 mole KCl 1 mole H2 OMass:HCl: (1 mol)( g/mol) (1 mol)( g/mol) gKOH: (1 mol)( g/mol) (1 mol)( g/mol) (1 mol)( g/mol) gKCl: (1 mol)( g/mol) (1 mol)( g/mol) gH2O: (2 mol)( g/mol) (1 mol)( g/mol) g HCl g KOH g KCl g g reactants g productsc.

2 2Mg(s) O2(g) 2 MgO(s)2 atoms Mg 1 moleculeO2 0 2 formula units MgO2 moles Mg 1 mole O2 2 moles MgOMass:2Mg: (2 mol)( g/mol) gO2: (2 mol)( g/mol) g2 MgO: (2 mol)( g/mol) (2 mol)( g/mol) g Mg g O2 g g reactants g products 2. 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 ___Na(s) ___H2O(l) ___NaOH(aq) ___H2(g)2Na(s) 2H2O(l) 2 NaOH(aq) 1H2(g)2 atoms Na 2 molecules H2O 2 formula units NaOH 1 molecule H22 mol Na 2 mol H2O 2 mol NaOH 1 mol H2 Mass:2Na: (2 mol)( g/mol) g2H2O: (4 mol)( g/mol) (2 mol)( g/mol) g2 NaOH: (2 mol)( g/mol) (2 mol)( g/mol) (2 mol)( g/mol) gH2: (2 mol)( g/mol) g Na g H2O g NaOH g g reactants g productsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, chemistry : Matter and Change Chapter 11 Solutions ManualSOLUTIONS MANUALCHAPTER11b.

3 ___Zn(s) ___HNO3(aq) ___Zn(NO3)2(aq) ___N2O(g) ___H2O(l)4Zn(s) 10 HNO3(aq) 4Zn(NO3)2(aq) 1N2O(g) 5H2O(l)4 atoms Zn 10 molecules HNO3 4 formula units Zn(NO3)2 1 molecule N2O 5 molecules H2O4 mol Zn 10 mol HNO3 4 mol Zn(NO3)2 1 mol N2O 5 mol H2 OMass:4Zn: (4 mol)( g/mol) g10 HNO3: (10 mol)( g/mol) (10 mol)( g/mol) (30 mol)( g/mol) g4Zn(NO3)2: (4 mol)( g/mol) (8 mol)( g/mol) (24 mol)( g/mol) gN2O: (2 mol)( g/mol) (1 mol)( g/mol) g5H2O: (10 mol)( g/mol) (5 mol)( g/mol) g Zn g HNO3 g Zn(NO3)2 g N2O g g reactants g products 3. Determine all possible mole ratios for the following balanced chemical 4Al(s) 3O2(g) 2Al2O3(s) 4 mol Al _ 3 mol O2 3 mol O2 __ 2 mol Al2O3 2 mol Al2O3 __ 4 mol Al 3 mol O2 _ 4 mol Al 2 mol Al2O3 __ 3 mol O2 4 mol Al __ 2 mol Al2O3 b. 3Fe(s) 4H2O(l) Fe3O4(s) 4H2(g) 3 mol Fe __ 4 mol H2O 3 mol Fe _ 4 mol H2 3 mol Fe __ 1 mol Fe3O4 4 mol H2O __ 3 mol Fe 4 mol H2 _ 3 mol Fe 1 mol Fe3O4 __ 3 mol Fe 1 mol Fe3O4 __ 4 mol H2 1 mol Fe3O4 __ 4 mol H2O 4 mol H2O __ 4 mol H2 4 mol H2 __ 1 mol Fe3O4 4 mol H2O __ 1 mol Fe3O4 4 mol H2 __ 4 mol H2O c.

4 2 HgO(s) 2Hg(l) O2(g) 2 mol HgO __ 2 mol Hg 1 mol O2 _ 2 mol Hg 1 mol O2 __ 2 mol HgO 2 mol Hg __ 2 mol HgO 2 mol Hg _ 1 mol O2 2 mol HgO __ 1 mol O2 4. Challenge Balance the following equations , and determine the possible mole ZnO(s) HCl(aq) ZnCl2(aq) H2O(l)ZnO(s) 2 HCl(aq) ZnCl2(aq) H2O(l) 1 mol ZnO __ 2 mol HCl 1 mol ZnO __ 1 mol ZnCl2 1 mol ZnO __ 1 mol H2O 2 mol HCl __ 1 mol ZnO 2 mol HCl __ 1 mol ZnCl2 2 mol HCl __ 1 mol H2O 1 mol ZnCl2 __ 1 mol ZnO 1 mol ZnCl2 __ 2 mol HCl 1 mol ZnCl2 __ 1 mol H2O 1 mol H2O __ 1 mol ZnO 1 mol H2O __ 2 mol HCl 1 mol H2O __ 1 mol ZnCl2 b. butane (C4H10) oxygen carbon dioxide water2C4H10(g) 13O2(g) 0 8CO2(g) 10H2O(l) 2 mol C4H10 __ 13 mol O2 2 mol C4H10 __ 8 mol CO2 2 mol C4H10 __ 10 mol H2O 13 mol O2 __ 2 mol C4H10 8 mol CO2 __ 2 mol C4H10 10 mol H2O __ 2 mol C4H10 10 mol H2O __ 13 mol O2 10 mol H2O __ 8 mol CO2 8 mol CO2 _ 13 mol O2 13 mol O2 __ 10 mol H2O 8 mol CO2 __ 10 mol H2O 13 mol O2 _ 8 mol CO2 Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Manual chemistry : Matter and Change Chapter 11 211 SOLUTIONS MANUALCHAPTER11 Section Assessmentpage 372 5.

5 Compare the mass of the reactants and the mass of the products in a chemical reaction, and explain how these masses are coefficients in the balanced equation indicate the molar relationship between each pair of reactants and products. The masses of reactants and products are equal. 6. State how many mole ratios can be written for a chemical reaction involving three 3, thus (n)(n 1) (3)(2) 6 mole ratios 7. Categorize the ways in which a balancedchemical equation can be (atoms, molecules, formula units), moles, and mass 8. Apply The general form of a chemical reac-tion is xA yB zAB. In the equation, A and B are elements and x, y, and z are coefficients. State the mole ratios for this and xA/zAByB/xA and yB/zABzAB/xA and zAB/yB 9. Apply Hydrogen peroxide (H2O2) decomposes to produce water and oxygen. Write a balanced chemical equation for this reaction, and deter-mine the possible mole 2H2O O22 mol H2O2/2 mol H2O, 2 mol H2O2/1 mol O2, 2 mol H2O/2 mol H2O2, 2 mol H2O/1 mol O2, 1 mol O2/2 mol H2O2, 1 mol O2/2 mol H2O 10.

6 Model Write the mole ratios for the reaction of hydrogen gas and oxygen gas, 2H2(g) O2(g) 2H2O. Make a sketch of six hydrogen molecules reacting with the correct number of oxygen molecules. Show the water molecules 3O2 6H2O2H2/O2 and 2H2/2H2OO2/2H2 and O2/2H2O2H2O/2H2 and 2H2O/O2 Sketches should show six hydrogen atoms combining with three oxygen atoms to form six water molecules. Section Stoichiometric Calculationspages 373 378 Practice Problemspages 375 377 11. Methane and sulfur react to produce carbon disulfide (CS2), a liquid often used in the production of cellophane. ___CH4(g) ___S8(s) ___CS2(l) ___H2S(g)a. Balance the (g) S8(s) 2CS2(l) 4H2S(g)b. Calculate the moles of CS2 produced when moles of S8 is mol S8 2 mol CS2 _ 1 mol S8 mol CS2 Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, chemistry : Matter and Change Chapter 11 Solutions ManualSOLUTIONS MANUALCHAPTER11c.

7 How many moles of H2S are produced? mol S8 4 mol H2S _ 1 mol S8 mol H2S 12. Challenge Sulfuric acid (H2SO4) is formed when sulfur dioxide (SO2) reacts with oxygen and Write the balanced chemical equation for the (g) O2(g) 2H2O(l) 2H2SO4(aq)b. How many moles of H2SO4 are produced from moles of SO2? mol SO2 2 mol H2SO4 __ 2 mol SO2 mol H2SO4 producedc. How many moles of O2 are needed? mol SO2 1 mol O2 _ 2 mol SO2 mol O2 needed 13. Sodium chloride is decomposed into the elements sodium and chlorine by means of electrical energy, as shown below. How much chlorine gas, in grams, is obtained from the process? mol? gElectricenergyNaClCl2 NaStep 1: Balance the chemical (s) 2Na(s) Cl2(g) Step 2: Make mole mole mol NaCl 1 mol Cl2 __ 2 mol NaCl mol Cl2 Step 3: Make mole mass mol Cl2 g Cl2 _ 1 mol Cl2 g Cl2 14. Challenge Titanium is a transition metal used in many alloys because it is extremely strong and lightweight.

8 Titanium tetrachloride (TiCl4) is extracted from titanium oxide (TiO2) using chlorine and coke (carbon). TiO2(s) C(s) 2Cl2(g) TiCl4(s) CO2(g)a. What mass of Cl2 gas is needed to react with mol of TiO2?Step 1: Make mole mole mol TiO2 2 mol Cl2 __ 1 mol TiO2 mol Cl2 Step 2: Make mole mass mol Cl2 g Cl2 __ 1 mol Cl2 177 g Cl2b. What mass of C is needed to react with mol of TiO2?Step 1: Make mole mole mol TiO2 1 mol C __ 1 mol TiO2 mol CStep 2: Make mole mass mol C g C __ 1 mol C g Cc. What is the mass of all of the products formed by reaction with mol of TiO2?Calculate the mass to TiO2 mol TiO2 g TiO2 __ 1 mol TiO2 g TiO2 Calculate the total mass of the g 177 g g 292 gBecause mass is conserved, the mass of the products must equal the mass of of products 292 gCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Manual chemistry : Matter and Change Chapter 11 213 SOLUTIONS MANUALCHAPTER11 15.

9 One of the reactions used to inflateautomobile air bags involves sodium azide (NaN3): 2 NaN3(s) 2Na(s) 3N2(g). Determine the mass of N2 produced from the decomposition of NaN3 shown g NaN3 ? g N2(g)N2 gas2 NaN3(s) 2Na(s) 3N2(g)Step 1: Make mass mole g NaN3 1 mol NaN3 __ g NaN3 mol NaN3 Step 2: Make mole mole mol NaN3 3 mol N2 __ 2 mol NaN3 mol N2 Step 3: Make mole mass mol N2 g N2 __ 1 mol N2 g N2 16. Challenge In the formation of acid rain, sulfur dioxide (SO2) reacts with oxygen and water in the air to form sulfuric acid (H2SO4). Write the balanced chemical equation for the reac-tion. If g of SO2 reacts with excess oxygen and water, how much H2SO4, in grams, is produced?Step 1: Balance the chemical (g) O2(g) 2H2O(l) 0 2H2SO4(aq)Step 2: Make mass mole g SO2 1 mol SO2 __ g SO2 mol SO2 Step 3: Make mole mole mol SO2 2 mol H2SO4 __ 2 mol SO2 mol H2SO4 Step 4: Make mole mass mol H2SO4 g H2SO4 __ 1 mol H2SO4 g H2SO4 Section Assessmentpage 378 17.

10 Explain why a balanced chemical equation is needed to solve a stoichiometric coefficients in the balanced equation indicate the molar relationship between each pair of reactants and products. 18. List the four steps used in solving stoichio-metric Balance the Convert the mass of the known substance to moles of known Use the mole ratio to convert from moles of the known to moles of the unknown. 4. Convert moles of unknown to mass of the unknown. 19. Describe how a mole ratio is correctly expressed when it is used to solve a stoichio-metric of unknown/moles of known 20. Apply How can you determine the mass of liquid bromine (Br2) needed to react completely with a given mass of magnesium?Write a balanced equation. Convert the given mass of magnesium to moles. Use the mole ratio from the balanced equation to convert moles of magnesium to moles of bromine. Convert from moles of bromine to mass of Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, chemistry : Matter and Change Chapter 11 Solutions ManualSOLUTIONS MANUALCHAPTER11 21.