Preview Chemistry Chemical Reactivity, 9E by John C. Kotz, Paul M. Treichel, John Townsend, David Treichel (2014)

Preview Chemistry Chemical Reactivity, 9E by John C. Kotz, Paul M. Treichel, John Townsend, David Treichel (2014) Preview Chemistry Chemical Reactivity, 9E by John C. Kotz, Paul M. Treichel, John Townsend, David Treichel (2014) Preview Chemistry Chemical Reactivity, 9E by John C. Kotz, Paul M. Treichel, John Townsend, David Treichel (2014) Preview Chemistry Chemical Reactivity, 9E by John C. Kotz, Paul M. Treichel, John Townsend, David Treichel (2014) Preview Chemistry Chemical Reactivity, 9E by John C. Kotz, Paul M. Treichel, John Townsend, David Treichel (2014)

Periodic Table of the Elements Hydrogen H MAIN GROUP METALS 1.0079 1A (1) 2A (2) Lithium Beryllium Li TRANSITION METALS Uranium 92 U METALLOIDS Be 6.941 9.0122 Sodium Magnesium 12 11 Na Mg 3B (3) 4B (4) 5B (5) 6B (6) 7B (7) 22.9898 24.3050 Potassium 19 Calcium 20 Scandium Titanium Vanadium Chromium Manganese 22 23 24 25 21 39.0983 40.078 44.9559 K Ca Rubidium Strontium 37 38 Rb Sr Sc Yttrium 39 Ti 47.867 V 50.9415 Cr 51.9961 Mn 54.9380 Y Zr Nb Hf Ta Tc W Re 132.9055 Francium 87 137.327 138.9055 178.49 180.9479 183.84 186.207 Radium Actinium Rutherfordium Dubnium Seaborgium Bohrium 105 107 88 104 106 89 Fr Ra 88.9059 91.224 92.9064 Lanthanum Hafnium Tantalum 57 72 73 Mo 87.62 Barium 56 Ba La Ac (223.02) (226.0254) (227.0278) Note: Atomic masses are 2009 IUPAC values (up to four decimal places) Numbers in parentheses are atomic masses or mass numbers of the most stable isotope of an element Atomic weight 8B (8) (9) (10) Iron 26 Cobalt 27 Nickel 28 55.845 58.9332 58.6934 Fe Co Ni Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium 45 40 41 42 43 44 46 85.4678 Cesium 55 Cs Symbol 238.0289 NONMETALS Atomic number Rf (265) Lanthanides Actinides Db (268) 95.96 (97.907) Tungsten Rhenium 75 74 Sg (271) Bh (270) Ru 101.07 Osmium 76 Os Rh Pd Ir Pt 102.9055 106.42 Iridium Platinum 77 78 190.23 192.22 195.084 Hassium Meitnerium Darmstadtium 108 109 110 Hs (277) Mt (276) Ds (281) Cerium 58 Praseodymium Neodymium Promethium Samarium Europium 59 60 61 63 62 140.116 140.9076 Ce Pr Nd 144.242 Pm (144.91) Sm 150.36 Eu 151.964 Thorium Protactinium Uranium Neptunium Plutonium Americium 92 94 90 91 93 95 Th Pa U Np Pu Am 232.0381 231.0359 238.0289 (237.0482) (244.664) (243.061) Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 8A (18) Helium 4A (14) 5A (15) 6A (16) 7A (17) 4.0026 He hydrogen atoms Boron Carbon Nitrogen Oxygen Fluorine Neon 10 oxygen atoms 10.811 Aluminum 13 12.011 Silicon 14 14.0067 15.9994 Phosphorus Sulfur 16 15 18.9984 Chlorine 17 20.1797 Argon 18 Al C Si N P O S F Cl Ne Ar 1B (11) 2B (12) 26.9815 28.0855 30.9738 32.066 35.4527 39.948 Copper 29 Zinc 30 Gallium 31 Germanium 32 Arsenic 33 Selenium 34 Bromine 35 Krypton 36 63.546 65.38 69.723 72.63 74.9216 78.96 79.904 83.798 Silver 47 Cadmium 48 Indium 49 Tin 50 Iodine 53 Xenon 54 107.8682 Gold 79 112.411 Mercury 80 114.818 Thallium 81 118.710 Lead 82 196.9666 200.59 204.3833 207.2 Ununtrium 113 Flerovium 112 (285) Discovered 2004 Ag Au Zn Cd Hg Roentgenium Copernicium 111 Rg (280) Cn Ga In Tl Uut Ge Sn Pb 114 Fl (289) Gadolinium Terbium Dysprosium Holmium 66 67 65 64 Gd Tb Dy Ho Antimony Tellurium 51 52 Sb 121.760 Bismuth 83 Te Br I 131.293 Radon 86 208.9804 (208.98) (209.99) (222.02) Po At Rn Ununpentium Livermorium Ununseptium Ununoctium 115 117 118 116 Uup Lv Uus (292) Erbium 68 Thulium 69 Ytterbium Lutetium 71 70 167.26 168.9342 173.054 174.9668 Er Tm Discovered 2010 Uuo Discovered 2004 Yb Discovered 2002 Lu Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium 97 100 98 99 101 102 103 Cf Es (251.08) (252.08) chlorine atoms Xe 127.60 126.9045 Polonium Astatine 85 84 Bi nitrogen atoms Kr Curium 96 Bk 164.9303 Se 158.9254 Cm 162.50 As 157.25 (247.07) (247.07) carbon atoms 3A (13) B Cu Standard Colors for Atoms in Molecular Models Fm Md (257.10) (258.10) No Lr (259.10) (262.11) Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Ninth Edition cHemistry & Chemical Reactivity John C Kotz State University of New York College at Oneonta Paul M Treichel University of Wisconsin–Madison John R Townsend West Chester University of Pennsylvania David A Treichel Nebraska Wesleyan University Australia • Brazil • Mexico • Singapore • United Kingdom • United States Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it This is an electronic version of the print textbook Due to electronic rights restrictions, some third party content may be suppressed Editorial review has deemed that any suppressed content does not materially affect the overall learning experience The publisher reserves the right to remove content from this title at any time if subsequent rights restrictions require it For valuable information on pricing, previous editions, changes to current editions, and alternate formats, please visit www.cengage.com/highered to search by ISBN#, author, title, or keyword for materials in your areas of interest Important Notice: Media content referenced within the product description or the product text may not be available in the eBook version Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Chemistry & Chemical Reactivity, Ninth Edition John C Kotz, Paul M Treichel, John R Townsend, and David A Treichel Product Director: Mary Finch Product Manager: Maureen Rosener Managing Developer: Peter McGahey Associate Developer: Elizabeth Woods Product Assistant: Karolina Kiwak Media Developer: Lisa Weber Marketing Director: Nicole Hamm Content Project 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Specialist: Don Schlotman Library of Congress Control Number: 2013952168 Production and Composition: Graphic World Inc ISBN-13: 978-1-133-94964-0 ISBN-10: 1-133-94964-9 Photo Researcher: QBS Learning Text Researcher: QBS Learning Copy Editor: Graphic World Inc Text Designer: Parallelogram Graphics Cover Designer: Irene Morris Cover Image: Main image ©John C Kotz, inset image ©Topic Photo Agency/Corbis Cengage Learning 200 First Stamford Place, 4th Floor Stamford, CT 06902 USA Cengage Learning is a leading provider of customized learning solutions with office locations around the globe, including Singapore, the United Kingdom, Australia, Mexico, Brazil, and Japan Locate your local office at www.cengage.com/global Cengage Learning products are represented in Canada by Nelson Education, Ltd To learn more about Cengage Learning Solutions, visit www.cengage.com Purchase any of our products at your local college store or at our preferred online store www.cengagebrain.com Printed in the United States of America 18 17 16 15 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Brief Contents c PA R T O N E 19 Principles of Chemical Reactivity: Electron Transfer Reactions | 712 the basic tools of chemistry Basic Concepts of Chemistry | c PA R T F I V E THE CHEMISTRY OF THE ELEMENTS Let’s Review: The Tools of Quantitative Chemistry | 22 Atoms, Molecules, and Ions | 44 Chemical Reactions | 96 Stoichiometry: Quantitative Information about Chemical Reactions | 138 Principles of Chemical Reactivity: Energy and Chemical Reactions | 180 c PA R T T W O ATOMS AND MOLECULES The Structure of Atoms | 218 The Structure of Atoms and Periodic Trends | 248 Bonding and Molecular Structure | 282 Bonding and Molecular Structure: Orbital Hybridization and Molecular Orbitals | 338 c PA R T T H R E E STATES OF MATTER 10 11 12 13 Gases and Their Properties | 370 Intermolecular Forces and Liquids | 404 The Solid State | 436 Solutions and Their Behavior | 468 c PA R T F O U R THE CONTROL OF CHEMICAL REACTIONS 14 Chemical Kinetics: The Rates of Chemical 15 16 17 18 Reactions | 506 Principles of Chemical Reactivity: Equilibria | 554 Principles of Chemical Reactivity: The Chemistry of Acids and Bases | 584 Principles of Chemical Reactivity: Other Aspects of Aqueous Equilibria | 630 Principles of Chemical Reactivity: Entropy and Free Energy | 678 20 Environmental Chemistry—Earth’s Environment, 21 22 23 24 25 Energy, and Sustainability | 762 The Chemistry of the Main Group Elements | 802 The Chemistry of the Transition Elements | 856 Carbon: Not Just Another Element | 896 Biochemistry | 944 Nuclear Chemistry | 974 c LIST OF APPENDICES A Using Logarithms and Solving Quadratic B C D E F G H I J K L M N Equations | A-2 Some Important Physical Concepts | A-6 Abbreviations and Useful Conversion Factors | A-9 Physical Constants | A-13 A Brief Guide to Naming Organic Compounds | A-15 Values for the Ionization Energies and Electron Attachment Enthalpies of the Elements | A-18 Vapor Pressure of Water at Various Temperatures | A-19 Ionization Constants for Aqueous Weak Acids at 25 °C | A-20 Ionization Constants for Aqueous Weak Bases at 25 °C | A-22 Solubility Product Constants for Some Inorganic Compounds at 25 °C | A-23 Formation Constants for Some Complex Ions in Aqueous Solution at 25 °C | A-25 Selected Thermodynamic Values | A-26 Standard Reduction Potentials in Aqueous Solution at 25 °C | A-34 Answers to Study Questions, Review & Check, Check Your Understanding, and Case Study Questions | A-38 c Index/Glossary I-1 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it iii Contents Preface  XIX PART ONE c THE BASIC TOOLS OF CHEMISTRY Basic Concepts of Chemistry  Gold! 1 Experimental Error  29 1-1 Chemistry and Its Methods  Hypotheses, Laws, and Theories  Goals of Science  Standard Deviation  31 A Closer Look: Principles of Green Chemistry 6 1-3 Classifying Matter  States of Matter and Kinetic-Molecular Theory  Significant Figures  33 Mixtures: Heterogeneous and Homogeneous  1-4 Elements  10 1-5 Compounds  11 A Closer Look: Element Names and Symbols 12 1-6 Physical Properties  13 Extensive and Intensive Properties  14 1-7 Physical and Chemical Changes  15 1-8 Energy: Some Basic Principles  17 Conservation of Energy  18 Case Study: CO2 in the Oceans  19 CHAPTER GOALS REVISITED 20 KEY EQUATION 21 STUDY QUESTIONS 21 Let’s Review: The Tools of Quantitative Chemistry  22 Copper 22 1 Units of Measurement  23 Temperature Scales  24 Problem Solving by Dimensional Analysis  38 Graphs and Graphing  39 Case Study: Out of Gas!  40 Problem Solving and Chemical Arithmetic  41 STUDY QUESTIONS  43a Matter at the Macroscopic and Particulate Levels  Pure Substances  Mathematics of Chemistry  32 Exponential or Scientific Notation  32 Dilemmas and Integrity in Science  1-2 Sustainability and Green Chemistry  Making Measurements: Precision, Accuracy, Experimental Error, and Standard Deviation  29 Atoms, Molecules, and Ions  44 “Seeing” Atoms  44 2-1 Atomic Structure—Protons, Electrons, and Neutrons  45 2-2 Atomic Number and Atomic Mass  46 Atomic Number  46 Relative Atomic Mass and the Atomic Mass Unit 46 Mass Number  47 2-3 Isotopes 48 Isotope Abundance  49 Determining Atomic Mass and Isotope Abundance 49 2-4 Atomic Weight  50 2-5 The Periodic Table  52 Case Study: Using Isotopes: Ötzi, the Iceman of the Alps  53 Features of the Periodic Table  53 Key Experiments: How Do We Know the Nature of the Atom and Its Components?  54 Energy Units  27 A Closer Look: Mendeleev and the Periodic Table 57 A Closer Look: Energy and Food  28 A Brief Overview of the Periodic Table and the Chemical Elements  58 Length, Volume, and Mass  25 iv Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Contents 2-6 Molecules, Compounds, and Formulas  63 3-4 Aqueous Solutions  105 Formulas 63 Ions and Molecules in Aqueous Solutions  105 Molecular Models  64 Solubility of Ionic Compounds in Water  107 2-7 Ionic Compounds: Formulas, Names, and Properties  65 3-5 Precipitation Reactions  110 Ions 66 Predicting the Outcome of a Precipitation Reaction 110 Formulas of Ionic Compounds  68 Net Ionic Equations  112 3-6 Acids and Bases  114 Names of Ions  71 Properties of Ionic Compounds  73 Acids and Bases: The Arrhenius Definition  116 A Closer Look: Hydrated Ionic Compounds 75 Acids and Bases: The Brønsted–Lowry Definition 116 2-8 Molecular Compounds: Formulas and A Closer Look: The Hydronium Ion— The H+ Ion in Water  118 2-9 Atoms, Molecules, and the Mole  77 Reactions of Acids and Bases  119 Names  76 A Closer Look: Amedeo Avogadro and His Number  78 Atoms and Molar Mass  78 Molecules, Compounds, and Molar Mass  80 Oxides of Nonmetals and Metals  121 A Closer Look: Sulfuric Acid  122 3-7 Gas-Forming Reactions  123 3-8 Oxidation–Reduction Reactions  125 Oxidation–Reduction Reactions and Electron Transfer 125 A Closer Look: The Mole, a Counting Unit  81 2-10 Chemical Analysis: Determining Compound Oxidation Numbers  127 Formulas  84 A Closer Look: Are Oxidation Numbers “Real”? 129 Percent Composition  84 Empirical and Molecular Formulas from Percent Composition 85 Determining a Formula from Mass Data  88 Recognizing Oxidation–Reduction Reactions  129 3-9 Classifying Reactions in Aqueous Solution  131 Case Study: Arsenic, Medicine, and the Formula of Compound 606  90 Case Study: Killing Bacteria with Silver  132 Determining a Formula by Mass Spectrometry  91 A Closer Look: Alternative Organizations of Reaction Types  133 A Closer Look: Mass Spectrometry, Molar Mass, and Isotopes  91 APPLYING CHEMICAL PRINCIPLES: SUPERCONDUCTORS  135 CHAPTER GOALS REVISITED  136 APPLYING CHEMICAL PRINCIPLES: ARGON—AN AMAZING DISCOVERY  92 STUDY QUESTIONS  137a CHAPTER GOALS REVISITED  93 KEY EQUATIONS  94 STUDY QUESTIONS  95 3 Chemical Reactions  v 96 Black Smokers and Volcanoes  96 3-1 Introduction to Chemical Equations  97 A Closer Look: Antoine Laurent Lavoisier, 1743–1794 99 3-2 Balancing Chemical Equations  99 3-3 Introduction to Chemical Equilibrium  102 Stoichiometry: Quantitative Information about Chemical Reactions  138 Thermite 138 4-1 Mass Relationships in Chemical Reactions: Stoichiometry  139 4-2 Reactions in Which One Reactant Is Present in Limited Supply  143 A Stoichiometry Calculation with a Limiting Reactant 144 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 4-8 Spectrophotometry c Solve stoichiometry problems using solution concentrations (Section 4-7) Study Questions: 61–68, 106, 107 d Explain how a titration is carried out, explain the procedure of standardiza­ tion, and calculate concentrations or amounts of reactants from titration data (Section 4-7) Study Questions: 69–76 • • Use the relationship of pH and hydronium ion concentration a Calculate the pH of a solution from the concentration of hydronium ion in the solution Calculate the hydronium ion concentration of a solution from the pH (Section 4-6) Study Questions: 55–60 Use spectrophotometry to determine the concentration of a species in solution a Construct an absorbance versus concentration plot, and determine the slope and intercept (Section 4-8) Study Questions: 77, 78, 133 b Use an absorbance versus concentration plot to determine the concentra­ tion of unknown solution Study Questions: 77, 78, 133 REMEMBER • • That concentration (as molarity) is the amount of solute per liter of solution That pH is a measure of hydronium ion concentration key equations Equation 4.1 (page 147)  Percent yield Percent yield ϭ actual yield ϫ 100% theoretical yield Equation 4.2 (page 156)  Definition of molarity, a measure of the concentration of a solute in a solution Molarity of x (c x ) ϭ amount of solute x (mol) volume of solution (L) A useful form of this equation is Amount of solute x (mol) = cx (mol/L) × volume of solution (L) Dilution Equation (page 160)  This is a shortcut to find, for example, the con- centration of a solution (cd) after diluting some volume (Vc) of a more concentrated solution (cc) to a new volume (Vd) cc × Vc = cd × Vd Equation 4.3 (page 161)  pH The pH of a solution is the negative logarithm of the hydronium ion concentration pH = −log[H3O+] Equation 4.4 (page 162)  Calculating [H3O+] from pH The equation for calculating the hydronium ion concentration of a solution from the pH of the solution [H3O+] = 10−pH Equation 4.5 (page 175)  Beer–Lambert law The absorbance of light (A) by a substance in solution is equal to the product of the molar absorptivity of the substance (ε), the path length of the cell (ℓ), and the concentration of the solute (c) Absorbance (A) ∝ path length (ℓ) × concentration (c) A=ε×ℓ×c Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179 Stu d y Q u e s t i o n s © Cengage Learning/Charles D Winters ▲  denotes challenging questions Blue-numbered questions have answers in Appendix N and fully worked solutions in the Student Solutions Manual Practicing Skills Mass Relationships in Chemical Reactions: Basic Stoichiometry (See Example 4.1.) In a reaction known as the thermite reaction, iron(III) oxide reacts with aluminum to give molten iron Fe2O3(s) + Al(s) n Fe(ℓ) + Al2O3(s) What amount of Al, in moles, is needed for complete reaction with 3.0 mol of Fe2O3? What mass of Fe, in grams, can be produced? What mass of HCl, in grams, is required to react with 0.750 g of Al(OH)3? What mass of water, in grams, is produced? Al(OH)3(s) + HCl(aq) n AlCl3(aq) + H2O(ℓ) Like many metals, aluminum reacts with a halogen to give a metal halide (page 99) Al(s) + Br2(ℓ) n Al2Br6(s) What mass of Br2, in grams, is required for complete reaction with 2.56 g of Al? What mass of white, solid Al2Br6 is expected? The balanced equation for the reduction of iron ore to the metal using CO is Fe2O3(s) + CO(g) n Fe(s) + CO2(g) (a) What is the maximum mass of iron, in grams, that can be obtained from 454 g (1.00 lb) of iron(III) oxide? (b) What mass of CO is required to react with 454 g of Fe2O3? Methane, CH4, burns in oxygen (a) What are the products of the reaction? (b) Write the balanced equation for the reaction (c) What mass of O2, in grams, is required for complete combustion of 25.5 g of methane? (d) What is the total mass of products expected from the combustion of 25.5 g of methane? The formation of water-insoluble silver chloride is useful in the analysis of chloride-containing substances Consider the following unbalanced equation: BaCl2(aq) + AgNO3(aq) n AgCl(s) + Ba(NO3)2(aq) (a) Write the balanced equation (b) What mass of AgNO3, in grams, is required for complete reaction with 0.156 g of BaCl2? What mass of AgCl is produced? Amounts Tables and Chemical Stoichiometry For each question below, set up an amounts table that lists the initial amount or amounts of reactants, the changes in amounts of reactants and products, and the amounts of reactants and products after reaction (see page 140 and Example 4.1) The metals industry was a major source of air pollution years ago One common process involved “roasting” metal sulfides in the air: PbS(s) + O2(g) n PbO(s) + SO2(g) If 2.50 mol of PbS is heated in air, what amount of O2 is required for complete reaction? What amounts of PbO and SO2 are expected? Iron ore is converted to iron metal in a reaction with carbon Fe2O3(s) + C(s) n Fe(s) + CO2(g) If 6.2 mol of Fe2O3(s) is used, what amount of C(s) is needed, and what amounts of Fe and CO2 are produced? Chromium metal reacts with oxygen to give chromium(III) oxide, Cr2O3 (a) Write a balanced equation for the reaction (b) What mass (in grams) of Cr2O3 is produced if 0.175 g of chromium metal is converted completely to the oxide? (c) What mass of O2 (in grams) is required for the reaction? 10 Ethane, C2H6, burns in oxygen (a) What are the products of the reaction? (b) Write the balanced equation for the reaction (c) What mass of O2, in grams, is required for complete combustion of 13.6 of ethane? (d) What is the total mass of products expected from the combustion of 13.6 g of ethane? 179a Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Study Questions 179b 16 Aluminum chloride, AlCl3, is made by treating scrap aluminum with chlorine Limiting Reactants (See Example 4.2.) 11 Sodium sulfide, Na2S, is used in the leather industry to remove hair from hides The Na2S is made by the reaction Na2SO4(s) + C(s) n Na2S(s) + CO(g) Suppose you mix 15 g of Na2SO4 and 7.5 g of C Which is the limiting reactant? What mass of Na2S is produced? 12 Ammonia gas can be prepared by the reaction of a metal oxide such as calcium oxide with ammonium chloride CaO(s) + NH4Cl(s) n  NH3(g) + H2O(g) + CaCl2(s) If 112 g of CaO and 224 g of NH4Cl are mixed, what is the limiting reactant, and what mass of NH3 can be produced? 13 The compound SF6 is made by burning sulfur in an atmosphere of fluorine The balanced equation is S8(s) + 24 F2(g) n SF6(g) Starting with a mixture of 1.6 mol of sulfur, S8, and 35 mol of F2, (a) Which is the limiting reagent? (b) What amount of SF6 is produced? 14 Disulfur dichloride, S2Cl2, is used to vulcanize rubber It can be made by treating molten sulfur with gaseous chlorine: S8(ℓ) + Cl2(g) n S2Cl2(ℓ) Starting with a mixture of 32.0 g of sulfur and 71.0 g of Cl2, (a) Which is the limiting reactant? (b) What is the theoretical yield of S2Cl2? (c) What mass of the excess reactant remains when the reaction is completed? 15 The reaction of methane and water is one way to prepare hydrogen for use as a fuel: CH4(g) + H2O(g) n CO(g) + H2(g) If you begin with 995 g of CH4 and 2510 g of water, (a) Which reactant is the limiting reactant? (b) What is the maximum mass of H2 that can be prepared? (c) What mass of the excess reactant remains when the reaction is completed? Al(s) + Cl2(g) n AlCl3(s) If you begin with 2.70 g of Al and 4.05 g of Cl2, (a) Which reactant is limiting? (b) What mass of AlCl3 can be produced? (c) What mass of the excess reactant remains when the reaction is completed? (d) Set up an amounts table for this problem 17 In the thermite reaction, iron(III) oxide is reduced by aluminum to give molten iron Fe2O3(s) + Al(s) n Fe(ℓ) + Al2O3(s) If you begin with 10.0 g of Fe2O3 and 20.0 g of Al, (a) Which reactant is limiting? (b) What mass of Fe can be produced? (c) What mass of the excess reactant remains after the limiting reactant is consumed? (d) Set up an amounts table for this problem 18 Aspirin, C6H4(OCOCH3)CO2H, is produced by the reaction of salicylic acid, C6H4(OH)CO2H, and acetic anhydride, (CH3CO)2O (page 149) C6H4(OH)CO2H(s) + (CH3CO)2O(ℓ) n C6H4(OCOCH3)CO2H(s) + CH3CO2H(ℓ) If you mix 100 g of each of the reactants, what is the maximum mass of aspirin that can be obtained? Percent Yield (See Section 4-3.) 19 In Example 4.2, you found that a particular mixture of CO and H2 could produce 407 g CH3OH CO(g) + H2(g) n CH3OH(ℓ) If only 332 g of CH3OH is actually produced, what is the percent yield of the compound? 20 Ammonia gas can be prepared by the following reaction: CaO(s) + NH4Cl(s) n  NH3(g) + H2O(g) + CaCl2(s) If 112 g of CaO and 224 g of NH4Cl are mixed, the theoretical yield of NH3 is 68.0 g (Study Question 12) If only 16.3 g of NH3 is actually obtained, what is its percent yield? 21 The deep blue compound Cu(NH3)4SO4 is made by the reaction of copper(II) sulfate and ammonia CuSO4(aq) + NH3(aq) n Cu(NH3)4SO4(aq) (a) If you use 10.0 g of CuSO4 and excess NH3, what is the theoretical yield of Cu(NH3)4SO4? (b) If you isolate 12.6 g of Cu(NH3)4SO4, what is the percent yield of Cu(NH3)4SO4? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179c C hapter Stoichiometry: Quantitative Information about Chemical Reactions 22 Black smokers are found in the depths of the oceans (page 96) Thinking that the conditions in these smokers might be conducive to the formation of organic compounds, two chemists in Germany found the following reaction could occur in similar conditions CH3SH + CO n CH3COSCH3 + H2S If you begin with 10.0 g of CH3SH and excess CO, (a) What is the theoretical yield of CH3COSCH3? (b) If 8.65 g of CH3COSCH3 is isolated, what is its percent yield? 23 The reaction of methane and water is one way to prepare hydrogen for use as a fuel: CH4(g) + H2O(g) n CO(g) + H2(g) Under certain conditions, what mass of CH4 is required to produce 15 g of H2 if this reaction has a 37% yield? 29 Nickel(II) sulfide, NiS, occurs naturally as the relatively rare mineral millerite One of its occurrences is in meteorites To analyze a mineral sample for the quantity of NiS, the sample is dissolved in nitric acid to form a solution of Ni(NO3)2 NiS(s) + HNO3(aq) n Ni(NO3)2(aq) + NO2(g) + H2O(ℓ) + S(s) The aqueous solution of Ni(NO3)2 is then reacted with the organic compound dimethylglyoxime (C4H8N2O2) to give the red solid Ni(C4H7N2O2)2 Ni(NO3)2(aq) + C4H8N2O2(aq) n Ni(C4H7N2O2)2(s) + HNO3(aq) Suppose a 0.468-g sample containing millerite produces 0.206 g of red, solid Ni(C4H7N2O2)2 What is the mass percent of NiS in the sample? CO(g) + H2(g) n CH3OH(ℓ) What mass of hydrogen is required to produce 1.0 L of CH3OH (d = 0.791 g/mL) if this reaction has a 74% yield under certain conditions? Analysis of Mixtures (See Example 4.3.) 25 A mixture of CuSO4 and CuSO4 ⋅ H2O has a mass of 1.245 g After heating to drive off all the water, the mass is only 0.832 g What is the mass percent of CuSO4 ⋅ H2O in the mixture? (See page 89.) 26 A 2.634-g sample containing impure CuCl2 ⋅ H2O was heated The sample mass after heating to drive off the water was 2.125 g What was the mass percent of CuCl2 ⋅ H2O in the original sample? 27 A sample of limestone and other soil materials was heated, and the limestone decomposed to give calcium oxide and carbon dioxide CaCO3(s) n CaO(s) + CO2(g) A 1.506-g sample of limestone-containing material gave 0.558 g of CO2, in addition to CaO, after being heated at a high temperature What was the mass percent of CaCO3 in the original sample? 28 At higher temperatures, NaHCO3 is converted quantitatively to Na2CO3 NaHCO3(s) n Na2CO3(s) + CO2(g) + H2O(g) Heating a 1.7184-g sample of impure NaHCO3 gives 0.196 g of CO2 What was the mass percent of NaHCO3 in the original 1.7184-g sample? © Cengage Learning/Charles D Winters 24 Methanol, CH3OH, can be made from the reaction of carbon monoxide and hydrogen A precipitate of nickel with dimethylglyoxime 30 ▲ The aluminum in a 0.764-g sample of an unknown material was precipitated as aluminum hydroxide, Al(OH)3, which was then converted to Al2O3 by heating strongly If 0.127 g of Al2O3 is obtained from the 0.764-g sample, what is the mass percent of aluminum in the sample? Using Stoichiometry to Determine Empirical and Molecular Formulas (See Examples 4.4 and 4.5.) 31 Styrene, the building block of polystyrene, consists of only C and H If 0.438 g of styrene is burned in oxygen and produces 1.481 g of CO2 and 0.303 g of H2O, what is the empirical formula of styrene? 32 Mesitylene is a liquid hydrocarbon Burning 0.115 g of the compound in oxygen gives 0.379 g of CO2 and 0.1035 g of H2O What is the empirical formula of mesitylene? 33 Naphthalene is a hydrocarbon that once was used in mothballs If 0.3093 g of the compound is burned in oxygen, 1.0620 g of CO2 and 0.1739 g of H2O are isolated (a) What is the empirical formula of naphthalene? (b) If a separate experiment gave 128.2 g/mol as the molar mass of the compound, what is its molecular formula? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Study Questions 34 Azulene is a beautiful blue hydrocarbon If 0.106 g of the compound is burned in oxygen, 0.364 g of CO2 and 0.0596 g of H2O are isolated (a) What is the empirical formula of azulene? (b) If a separate experiment gave 128.2 g/mol as the molar mass of the compound, what is its molecular formula? 35 An unknown compound has the formula CxHyOz You burn 0.0956 g of the compound and isolate 0.1356 g of CO2 and 0.0833 g of H2O What is the empirical formula of the compound? If the molar mass is 62.1 g/mol, what is the molecular formula? 36 An unknown compound has the formula CxHyOz You burn 0.1523 g of the compound and isolate 0.3718 g of CO2 and 0.1522 g of H2O What is the empirical formula of the compound? If the molar mass is 72.1 g/mol, what is the molecular formula? 37 Nickel forms a compound with carbon monoxide, Nix(CO)y To determine its formula, you carefully heat a 0.0973-g sample in air to convert the nickel to 0.0426 g of NiO and the CO to 0.100 g of CO2 What is the empirical formula of Nix(CO)y? 38 To find the formula of a compound composed of iron and carbon monoxide, Fex(CO)y, the compound is burned in pure oxygen to give Fe2O3 and CO2 If you burn 1.959 g of Fex(CO)y and obtain 0.799 g of Fe2O3 and 2.200 g of CO2, what is the empirical formula of Fex(CO)y? Solution Concentration (See Examples 4.6 and 4.7.) 39 If 6.73 g of Na2CO3 is dissolved in enough water to make 250 mL of solution, what is the molar concentration of the sodium carbonate? What are the molar concentrations of the Na+ and CO32− ions? 40 Some potassium dichromate (K2Cr2O7), 2.335 g, is dissolved in enough water to make exactly 500 mL of solution What is the molar concentration of the potassium dichromate? What are the molar concentrations of the K+ and Cr2O72− ions? 41 What is the mass of solute, in grams, in 250 mL of a 0.0125 M solution of KMnO4? 42 What is the mass of solute, in grams, in 125 mL of a 1.023 × 10−3 M solution of Na3PO4? What is the molar concentration of the Na+ and PO43− ion? 43 What volume of 0.123 M NaOH, in milliliters, contains 25.0 g of NaOH? 44 What volume of 2.06 M KMnO4, in liters, contains 322 g of solute? 179d 45 Identify the ions that exist in each aqueous solution, and specify the concentration of each ion (a) 0.25 M (NH4)2SO4 (b) 0.123 M Na2CO3 (c) 0.056 M HNO3 46 Identify the ions that exist in each aqueous solution, and specify the concentration of each ion (a) 0.12 M BaCl2 (b) 0.0125 M CuSO4 (c) 0.500 M K2Cr2O7 Preparing Solutions (See Examples 4.6 and 4.7.) 47 An experiment in your laboratory requires 500 mL of a 0.0200 M solution of Na2CO3 You are given solid Na2CO3, distilled water, and a 500.-mL volumetric flask Describe how to prepare the required solution 48 What mass of oxalic acid, H2C2O4, is required to prepare 250 mL of a solution that has a concentration of 0.15 M H2C2O4? 49 If you dilute 25.0 mL of 1.50 M hydrochloric acid to 500 mL, what is the molar concentration of the dilute acid? 50 If 4.00 mL of 0.0250 M CuSO4 is diluted to 10.0 mL with pure water, what is the molar concentration of copper(II) sulfate in the diluted solution? 51 Which of the following methods would you use to prepare 1.00 L of 0.125 M H2SO4? (a) Dilute 20.8 mL of 6.00 M H2SO4 to a volume of 1.00 L (b) Add 950 mL of water to 50.0 mL of 3.00 M H2SO4 52 Which of the following methods would you use to prepare 300 mL of 0.500 M K2Cr2O7? (a) Add 30.0 mL of 1.50 M K2Cr2O7 to 270 mL of water (b) Dilute 250 mL of 0.600 M K2Cr2O7 to a volume of 300 mL Serial Dilutions (See A Closer Look: Serial Dilutions, page 162.) 53 You have 250 mL of 0.136 M HCl Using a volumetric pipet, you take 25.00 mL of that solution and dilute it to 100.00 mL in a volumetric flask Now you take 10.00 mL of that solution, using a volumetric pipet, and dilute it to 100.00 mL in a volumetric flask What is the concentration of hydrochloric acid in the final solution? 54 ▲ Suppose you have 100.00 mL of a solution of a dye and transfer 2.00 mL of the solution to a 100.00-mL volumetric flask After adding water to the 100.00 mL mark, you take 5.00 mL of that solution and again dilute to 100.00 mL If you find the dye concentration in the final diluted sample is 0.000158 M, what was the dye concentration in the original solution? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179e C hapter Stoichiometry: Quantitative Information about Chemical Reactions Calculating and Using pH (See Example 4.8.) 65 In the photographic developing process, silver bromide is dissolved by adding sodium thiosulfate 55 A table wine has a pH of 3.40 What is the hydronium ion concentration of the wine? Is it acidic or basic? AgBr(s) + Na2S2O3(aq) n Na3Ag(S2O3)2(aq) + NaBr(aq) 56 A saturated solution of milk of magnesia, Mg(OH)2, has a pH of 10.5 What is the hydronium ion concentration of the solution? Is the solution acidic or basic? If you want to dissolve 0.225 g of AgBr, what volume of 0.0138 M Na2S2O3, in milliliters, should be used? 57 What is the hydronium ion concentration of a 0.0013 M solution of HNO3? What is its pH? Photos: © Cengage Learning/Charles D Winters 58 What is the hydronium ion concentration of a 1.2 × 10−4 M solution of HClO4? What is its pH? 59 Make the following conversions In each case, tell whether the solution is acidic or basic pH (a) 1.00 (b) 10.50 (c) (d) [H3O+] 1.3 × 10−5 M 2.3 × 10−8 M 60 Make the following conversions In each case, tell whether the solution is acidic or basic pH (a) (b) (c) 5.25 (d) [H3O+] 6.7 × 10−10 M 2.2 × 10−6 M 2.5 × 10−2 M Stoichiometry of Reactions in Solution (See Example 4.9.) 61 What volume of 0.109 M HNO3, in milliliters, is required to react completely with 2.50 g of Ba(OH)2? HNO3(aq) + Ba(OH)2(s) n H2O(ℓ) + Ba(NO3)2(aq) 62 What mass of Na2CO3, in grams, is required for complete reaction with 50.0 mL of 0.125 M HNO3? Na2CO3(aq) + HNO3(aq) n  NaNO3(aq) + CO2(g) + H2O(ℓ) 63 When an electric current is passed through an aqueous solution of NaCl, the valuable industrial chemicals H2(g), Cl2(g), and NaOH are produced NaCl(aq) + H2O(ℓ) n H2(g) + Cl2(g) + NaOH(aq) What mass of NaOH can be formed from 15.0 L of 0.35 M NaCl? What mass of chlorine is obtained? 64 Hydrazine, N2H4, a base like ammonia, can react with sulfuric acid N2H4(aq) + H2SO4(aq) n N2H5+(aq) + SO42−(aq) What mass of hydrazine reacts with 250 mL of 0.146 M H2SO4? (a) (b) Silver chemistry.  (a) A precipitate of AgBr formed by adding AgNO3(aq) to KBr(aq) (b) On adding Na2S2O3(aq), sodium thiosulfate, the solid AgBr dissolves 66 You can dissolve an aluminum soft drink can in an aqueous base such as potassium hydroxide Al(s) + KOH(aq) + H2O(ℓ) n  KAl(OH)4(aq) + H2(g) If you place 2.05 g of aluminum in a beaker with 185 mL of 1.35 M KOH, will any aluminum remain? What mass of KAl(OH)4 is produced? 67 What volume of 0.750 M Pb(NO3)2, in milliliters, is required to react completely with 1.00 L of 2.25 M NaCl solution? The balanced equation is Pb(NO3)2(aq) + NaCl(aq) n PbCl2(s) + NaNO3(aq) 68 What volume of 0.125 M oxalic acid, H2C2O4, is required to react with 35.2 mL of 0.546 M NaOH? H2C2O4(aq) + NaOH(aq) n Na2C2O4(aq) + H2O(ℓ) Titrations (See Examples 4.10–4.13.) 69 What volume of 0.812 M HCl, in milliliters, is required to titrate 1.45 g of NaOH to the equivalence point? NaOH(aq) + HCl(aq) n H2O(ℓ) + NaCl(aq) 70 What volume of 0.955 M HCl, in milliliters, is required to titrate 2.152 g of Na2CO3 to the equivalence point? Na2CO3(aq) + HCl(aq) n H2O(ℓ) + CO2(g) + NaCl(aq) Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Study Questions 71 If 38.55 mL of HCl is required to titrate 2.150 g of Na2CO3 according to the following equation, what is the concentration (mol/L) of the HCl solution? Na2CO3(aq) + HCl(aq) n  NaCl(aq) + CO2(g) + H2O(ℓ) 72 Potassium hydrogen phthalate, KHC8H4O4, is used to standardize solutions of bases The acidic anion reacts with strong bases according to the following net ionic equation: HC8H4O4−(aq) + OH (aq) n − C8H4O42−(aq) + H2O(ℓ) If a 0.902-g sample of potassium hydrogen phthalate is dissolved in water and titrated to the equivalence point with 26.45 mL of NaOH(aq), what is the molar concentration of the NaOH? 73 You have 0.954 g of an unknown acid, H2A, which reacts with NaOH according to the balanced equation H2A(aq) + NaOH(aq) n Na2A(aq) + H2O(ℓ) If 36.04 mL of 0.509 M NaOH is required to titrate the acid to the second equivalence point, what is the molar mass of the acid? 74 An unknown solid acid is either citric acid or tartaric acid To determine which acid you have, you titrate a sample of the solid with aqueous NaOH and from this determine the molar mass of the unknown acid The appropriate equations are as follows: A 1.00-g “chewable” vitamin C tablet requires 27.85 mL of 0.102 M Br2 for titration to the equivalence point What is the mass of vitamin C in the tablet? Spectrophotometry (See Section 4-8 and Example 4.14 The problems below are adapted from Fundamentals of Analytical Chemistry, 8th ed., by D A Skoog, D M West, F J Holler, and S R Crouch, Thomson/Brooks-Cole, Belmont, CA 2004.) 77 A solution of a dye was analyzed by spectrophotometry, and the following calibration data were collected Dye Concentration Absorbance (A) at 475 nm 0.50 × 10−6 M  1.5 × 10−6 M  2.5 × 10−6 M  3.5 × 10−6 M  4.5 × 10−6 M 0.24 0.36 0.44 0.59 0.70 (a) Construct a calibration plot, and determine the slope and intercept (b) What is the dye concentration in a solution with A = 0.52? 78 The nitrite ion is involved in the biochemical nitrogen cycle You can determine the nitrite ion content of a sample using spectrophotometry by first using several organic compounds to form a colored compound from the ion The following data were collected Citric acid: H3C6H5O7(aq) + NaOH(aq) n  H2O(ℓ) + Na3C6H5O7(aq) Tartaric acid: H2C4H4O6(aq) + NaOH(aq) n  H2O(ℓ) + Na2C4H4O6(aq) A 0.956-g sample requires 29.1 mL of 0.513 M NaOH to consume the acid completely What is the unknown acid? 75 To analyze an iron-containing compound, you convert all the iron to Fe2+ in aqueous solution and then titrate the solution with standardized KMnO4 The balanced, net ionic equation is MnO4−(aq) + Fe2+(aq) + H3O+(aq) n Mn2+(aq) + Fe3+(aq) + 12 H2O(ℓ) A 0.598-g sample of the iron-containing compound requires 22.25 mL of 0.0123 M KMnO4 for titration to the equivalence point What is the mass percent of iron in the sample? 76 Vitamin C has the formula C6H8O6 Besides being an acid, it is a reducing agent One method for determining the amount of vitamin C in a sample is to titrate it with a solution of bromine, Br2, an oxidizing agent 179f NO2− Ion Concentration 2.00 × 10−6 M 6.00 × 10−6 M 10.00 × 10−6 M 14.00 × 10−6 M 18.00 × 10−6 M Unknown solution Absorbance of Solution at 550 nm 0.065 0.205 0.338 0.474 0.598 0.402 (a) Construct a calibration plot, and determine the slope and intercept (b) What is the nitrite ion concentration in the unknown solution? General Questions These questions are not designated as to type or location in the chapter They may combine several concepts 79 Suppose 16.04 g of benzene, C6H6, is burned in oxygen (a) What are the products of the reaction? (b) Write a balanced equation for the reaction (c) What mass of O2, in grams, is required for complete combustion of benzene? (d) What is the total mass of products expected from the combustion of 16.04 g of benzene? C6H8O6(aq) + Br2(aq) n HBr(aq) + C6H6O6(aq) Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179g Stoichiometry: Quantitative Information about Chemical Reactions C hapter 80 The metabolic disorder diabetes causes a buildup of acetone, CH3COCH3, in the blood Acetone, a volatile compound, is exhaled, giving the breath of untreated diabetics a distinctive odor The acetone is produced by a breakdown of fats in a series of reactions The equation for the last step, the breakdown of acetoacetic acid to give acetone and CO2, is 83 Some metal halides react with water to produce the metal oxide and the appropriate hydrogen halide (see photo) For example, TiCl4(ℓ) + H2O(ℓ) n TiO2(s) + HCl(g) Acetone, CH3COCH3 What mass of acetone can be produced from 125 mg of acetoacetic acid? 81 Your body deals with excess nitrogen by excreting it in the form of urea, NH2CONH2 The reaction producing it is the combination of arginine (C6H14N4O2) with water to give urea and ornithine (C5H12N2O2) C6H14N4O2 + H2O n NH2CONH2 + C5H12N2O2 arginine urea ornithine If you excrete 95 mg of urea, what mass of arginine must have been used? What mass of ornithine must have been produced? 82 The reaction of iron metal and chlorine gas to give iron(III) chloride is illustrated below The reaction of TiCl4 with the water in moist air (a) Name the four compounds involved in this reaction (b) If you begin with 14.0 mL of TiCl4 (d = 1.73 g/mL), what mass of water, in grams, is required for complete reaction? (c) What mass of each product is expected? 84 The reaction of 750 g each of NH3 and O2 was found to produce 562 g of NO (see pages 144–145) NH3(g) + O2(g) n NO(g) + H2O(ℓ) (a) What mass of water is produced by this reaction? (b) What mass of O2 is required to consume 750 g of NH3? 85 Sodium azide, an explosive chemical used in automobile airbags, is made by the following reaction: NaNO3 + NaNH2 n NaN3 + NaOH + NH3 © Cengage Learning/Charles D Winters © Cengage Learning/Charles D Winters CH3COCH2CO2H n CH3COCH3 + CO2 The reaction of iron and chlorine gas (a) Write the balanced chemical equation for the reaction (b) Beginning with 10.0 g of iron, what mass of Cl2, in grams, is required for complete reaction? What mass of FeCl3 can be produced? (c) If only 18.5 g of FeCl3 is obtained from 10.0 g of iron and excess Cl2, what is the percent yield? (d) If 10.0 g each of iron and chlorine are combined, what is the theoretical yield of iron(III) chloride? If you combine 15.0 g of NaNO3 with 15.0 g of NaNH2, what mass of NaN3 is produced? 86 Iodine is made by the following reaction NaIO3(aq) + NaHSO3(aq) n  NaHSO4(aq)+ Na2SO4(aq) + H2O(ℓ)+ I2(aq) (a) Name the two reactants (b) If you wish to prepare 1.00 kg of I2, what masses of NaIO3 and NaHSO3 are required? (c) What is the theoretical yield of I2 if you mixed 15.0 g of NaIO3 with 125 mL of 0.853 M NaHSO3? 87 Saccharin, an artificial sweetener, has the formula C7H5NO3S Suppose you have a sample of a saccharincontaining sweetener with a mass of 0.2140 g After decomposition to free the sulfur and convert it to the SO42− ion, the sulfate ion is trapped as water-insoluble BaSO4 (Figure 4.4) The quantity of BaSO4 obtained is 0.2070 g What is the mass percent of saccharin in the sample of sweetener? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Study Questions 88 ▲ Boron forms a series of compounds with hydrogen, all with the general formula BxHy B x H y (s) ϩ excess O2 (g) → x y B2O3(s) ϩ H 2O(g) 2 If 0.148 g of one of these compounds gives 0.422 g of B2O3 when burned in excess O2, what is its empirical formula? 89 ▲ Silicon and hydrogen form a series of compounds with the general formula SixHy To find the formula of one of them, a 6.22-g sample of the compound is burned in oxygen All of the Si is converted to 11.64 g of SiO2, and all of the H is converted to 6.980 g of H2O What is the empirical formula of the silicon compound? 90 ▲ Menthol, from oil of mint, has a characteristic odor The compound contains only C, H, and O If 95.6 mg of menthol burns completely in O2, and gives 269 mg of CO2 and 111 mg of H2O, what is the empirical formula of menthol? 91 ▲ Benzoquinone, a chemical used in the dye industry and in photography, is an organic compound containing only C, H, and O What is the empirical formula of the compound if 0.105 g of the compound gives 0.257 g of CO2 and 0.0350 g of H2O when burned completely in oxygen? 92 ▲ Aqueous solutions of iron(II) chloride and sodium sulfide react to form iron(II)sulfide and sodium chloride (a) Write the balanced equation for the reaction (b) If you combine 40 g each of Na2S and FeCl2, what is the limiting reactant? (c) What mass of FeS is produced? (d) What mass of Na2S or FeCl2 remains after the reaction? (e) What mass of FeCl2 is required to react completely with 40 g of Na2S? 93 Sulfuric acid can be prepared starting with the sulfide ore, cuprite (Cu2S) If each S atom in Cu2S leads to one molecule of H2SO4, what is the theoretical yield of H2SO4 from 3.00 kg of Cu2S? 94 ▲ In an experiment, 1.056 g of a metal carbonate, containing an unknown metal M, is heated to give the metal oxide and 0.376 g CO2 MCO3(s) + heat n MO(s) + CO2(g) What is the identity of the metal M? (a) M = Ni (b) M = Cu (c) M = Zn (d) M = Ba 95 ▲ An unknown metal reacts with oxygen to give the metal oxide, MO2 Identify the metal if a 0.356-g sample of the metal produces 0.452 g of the metal oxide 179h 96 ▲ Titanium(IV) oxide, TiO2, is heated in hydrogen gas to give water and a new titanium oxide, TixOy If 1.598 g of TiO2 produces 1.438 g of TixOy, what is the empirical formula of the new oxide? 97 ▲ Potassium perchlorate is prepared by the following sequence of reactions: Cl2(g) + KOH(aq) n KCl(aq) + KClO(aq) + H2O(ℓ) KClO(aq) n KCl(aq) + KClO3(aq) KClO3(aq) n KClO4(aq) + KCl(aq) What mass of Cl2(g) is required to produce 234 kg of KClO4? 98 ▲ Commercial sodium “hydrosulfite” is 90.1% Na2S2O4 The sequence of reactions used to prepare the compound is Zn(s) + SO2(g) n ZnS2O4(s) ZnS2O4(s) + Na2CO3(aq) n ZnCO3(s) + Na2S2O4(aq) (a) What mass of pure Na2S2O4 can be prepared from 125 kg of Zn, 500 g of SO2, and an excess of Na2CO3? (b) What mass of the commercial product would contain the Na2S2O4 produced using the amounts of reactants in part (a)? 99 What mass of lime, CaO, can be obtained by heating 125 kg of limestone that is 95.0% by mass CaCO3? CaCO3(s) n CaO(s) + CO2(g) 100 ▲ The elements silver, molybdenum, and sulfur combine to form Ag2MoS4 What is the maximum mass of Ag2MoS4 that can be obtained if 8.63 g of silver, 3.36 g of molybdenum, and 4.81 g of sulfur are combined? (Hint: What is the limiting reactant?) 101 ▲ A mixture of butene, C4H8, and butane, C4H10, is burned in air to give CO2 and water Suppose you burn 2.86 g of the mixture and obtain 8.80 g of CO2 and 4.14 g of H2O What are the mass percentages of butene and butane in the mixture? 102 ▲ Cloth can be waterproofed by coating it with a silicone layer This is done by exposing the cloth to (CH3)2SiCl2 vapor The silicon compound reacts with OH groups on the cloth to form a waterproofing film (density = 1.0 g/cm3) of [(CH3)2SiO]n, where n is a large integer number n (CH3)2SiCl2 + 2n OH− n 2n Cl− + n H2O + [(CH3)2SiO]n The coating is added layer by layer, with each layer of [(CH3)2SiO]n being 0.60 nm thick Suppose you want to waterproof a piece of cloth that is 3.00 square meters, and you want 250 layers of waterproofing compound on the cloth What mass of (CH3)2SiCl2 you need? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179i C hapter Stoichiometry: Quantitative Information about Chemical Reactions 103 ▲ Copper metal can be prepared by roasting copper ore, which can contain cuprite (Cu2S) and copper(II) sulfide Cu2S(s) + O2(g) n Cu(s) + SO2(g) CuS(s) + O2(g) n Cu(s) + SO2(g) Suppose an ore sample contains 11.0% impurity in addition to a mixture of CuS and Cu2S Heating 100.0 g of the mixture produces 75.4 g of copper metal with a purity of 89.5% What is the weight percent of CuS in the ore? The weight percent of Cu2S? 104 An Alka-Seltzer tablet contains exactly 100 mg of citric acid, H3C6H5O7, plus some sodium bicarbonate What mass of sodium bicarbonate is required to consume 100 mg of citric acid by the following reaction? H3C6H5O7(aq) + NaHCO3(aq) n  H2O(ℓ) + CO2(g) + Na3C6H5O7(aq) 105 ▲ Sodium bicarbonate and acetic acid react according to the equation NaHCO3(aq) + CH3CO2H(aq) n NaCH3CO2(aq) + CO2(g) + H2O(ℓ) What mass of sodium acetate can be obtained from mixing 15.0 g of NaHCO3 with 125 mL of 0.15 M acetic acid? 106 A noncarbonated soft drink contains an unknown amount of citric acid, H3C6H5O7 If 100 mL of the soft drink requires 33.51 mL of 0.0102 M NaOH to neutralize the citric acid completely, what mass of citric acid does the soft drink contain per 100 mL? The reaction of citric acid and NaOH is H3C6H5O7(aq) + NaOH(aq) n Na3C6H5O7(aq) + H2O(ℓ) 107 Sodium thiosulfate, Na2S2O3, is used as a “fixer” in black-and-white photography Suppose you have a bottle of sodium thiosulfate and want to determine its purity The thiosulfate ion can be oxidized with I2 according to the balanced, net ionic equation I2(aq) + S2O32−(aq) n I−(aq) + S4O62−(aq) If you use 40.21 mL of 0.246 M I2 in a titration, what is the weight percent of Na2S2O3 in a 3.232-g sample of impure material? 108 You have a mixture of oxalic acid, H2C2O4, and another solid that does not react with sodium hydroxide If 29.58 mL of 0.550 M NaOH is required to titrate the oxalic acid in the 4.554-g sample to the second equivalence point, what is the mass percent of oxalic acid in the mixture? Oxalic acid and NaOH react according to the equation H2C2O4(aq) + NaOH(aq) n Na2C2O4(aq) + H2O(ℓ) 109 (a) What is the pH of a 0.105 M HCl solution? (b) What is the hydronium ion concentration in a solution with a pH of 2.56? Is the solution acidic or basic? (c) A solution has a pH of 9.67 What is the hydronium ion concentration in the solution? Is the solution acidic or basic? (d) A 10.0-mL sample of 2.56 M HCl is diluted with water to 250 mL What is the pH of the dilute solution? 110 A solution of hydrochloric acid has a volume of 125 mL and a pH of 2.56 What mass of NaHCO3 must be added to completely consume the HCl? 111 ▲ One half liter (500 mL) of 2.50 M HCl is mixed with 250 mL of 3.75 M HCl Assuming the total solution volume after mixing is 750 mL, what is the concentration of hydrochloric acid in the resulting solution? What is its pH? 112 A solution of hydrochloric acid has a volume of 250 mL and a pH of 1.92 Exactly 250 mL of 0.0105 M NaOH is added What is the pH of the resulting solution? 113 ▲ You place 2.56 g of CaCO3 in a beaker containing 250 mL of 0.125 M HCl When the reaction has ceased, does any calcium carbonate remain? What mass of CaCl2 can be produced? CaCO3(s) + HCl(aq) n CaCl2(aq) + CO2(g) + H2O(ℓ) 114 The cancer drug cisplatin, Pt(NH3)2Cl2, can be made by reacting (NH4)2PtCl4 with ammonia in aqueous solution Besides cisplatin, the other product is NH4Cl (a) Write a balanced equation for this reaction (b) To obtain 12.50 g of cisplatin, what mass of (NH4)2PtCl4 is required? What volume of 0.125 M NH3 is required? (c) ▲  Cisplatin can react with the organic compound pyridine, C5H5N, to form a new compound Pt(NH3)2Cl2(aq) + x C5H5N(aq) n Pt(NH3)2Cl2(C5H5N)x(s) Suppose you treat 0.150 g of cisplatin with what you believe is an excess of liquid pyridine (1.50 mL; d = 0.979 g/mL) When the reaction is complete, you can find out how much pyridine was not used by titrating the solution with standardized HCl If 37.0 mL of 0.475 M HCl is required to titrate the excess pyridine, C5H5N(aq) + HCl(aq) n C5H5NH+(aq) + Cl−(aq) what is the formula of the unknown compound Pt(NH3)2Cl2(C5H5N)x? 115 ▲ You need to know the volume of water in a small swimming pool, but, owing to the pool’s irregular shape, it is not a simple matter to determine its dimensions and calculate the volume To solve the problem, you stir in a solution of a dye (1.0 g of methylene blue, C16H18ClN3S, Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it Study Questions in 50.0 mL of water) After the dye has mixed with the water in the pool, you take a sample of the water Using a spectrophotometer, you determine that the concentration of the dye in the pool is 4.1 × 10−8 M What is the volume of water in the pool? 116 ▲ Calcium and magnesium carbonates occur together in the mineral dolomite Suppose you heat a sample of the mineral to obtain the oxides, CaO and MgO, and then treat the oxide sample with hydrochloric acid If 7.695 g of the oxide sample requires 125 mL of 2.55 M HCl, CaO(s) + HCl(aq) n CaCl2(aq) + H2O(ℓ) MgO(s) + HCl(aq) n MgCl2(aq) + H2O(ℓ) what is the weight percent of each oxide (CaO and MgO) in the sample? 117 Gold can be dissolved from gold-bearing rock by treating the rock with sodium cyanide in the presence of oxygen Au(s) + NaCN(aq) + O2(g) + H2O(ℓ) n  NaAu(CN)2(aq) + NaOH(aq) (a) Name the oxidizing and reducing agents in this reaction What has been oxidized, and what has been reduced? (b) If you have exactly one metric ton (1 metric ton = 1000 kg) of gold-bearing rock, what volume of 0.075 M NaCN, in liters, you need to extract the gold if the rock is 0.019% gold? 118 ▲ You mix 25.0 mL of 0.234 M FeCl3 with 42.5 mL of 0.453 M NaOH (a) What mass of Fe(OH)3 (in grams) will precipitate from this reaction mixture? (b) One of the reactants (FeCl3 or NaOH) is present in a stoichiometric excess What is the molar concentration of the excess reactant remaining in solution after Fe(OH)3 has been precipitated? 119 ATOM ECONOMY: One type of reaction used in the chemical industry is a substitution, where one atom or group is exchanged for another In this reaction, an alcohol, 1-butanol, is transformed into 1-bromobutane by substituting Br for the –OH group in the presence of sulfuric acid CH3CH2CH2CH2OH + NaBr + H2SO4  n  CH3CH2CH2CH2Br + NaHSO4 + H2O Calculate the % atom economy for the desired product, CH3CH2CH2CH2Br 120 ATOM ECONOMY: Ethylene oxide, C2H4O, is an important industrial chemical [as it is the starting place to make such important chemicals as ethylene glycol (antifreeze) and various polymers] One way to make the compound is called the “chlorohydrin route.” 179j Another route is the modern catalytic reaction C2H4 + 1/2 O2  n C2H4O (a) Calculate the % atom economy for the production of C2H4O in each of these reactions Which is the more efficient method? (b) What is the percent yield of C2H4O if 867 g of C2H4 is used to synthesize 762 g of the product by the catalytic reaction? In the Laboratory 121 Suppose you dilute 25.0 mL of a 0.110 M solution of Na2CO3 to exactly 100.0 mL You then take exactly 10.0 mL of this diluted solution and add it to a 250-mL volumetric flask After filling the volumetric flask to the mark with distilled water (indicating the volume of the new solution is 250 mL), what is the concentration of the diluted Na2CO3 solution? 122 ▲ In some laboratory analyses, the preferred technique is to dissolve a sample in an excess of acid or base and then “back-titrate” the excess with a standard base or acid This technique is used to assess the purity of a sample of (NH4)2SO4 Suppose you dissolve a 0.475-g sample of impure (NH4)2SO4 in aqueous KOH (NH4)2SO4(aq) + KOH(aq) n  NH3(aq) + K2SO4(aq) + H2O(ℓ) The NH3 liberated in the reaction is distilled from the solution into a flask containing 50.0 mL of 0.100 M HCl The ammonia reacts with the acid to produce NH4Cl, but not all of the HCl is used in this reaction The amount of excess acid is determined by titrating the solution with standardized NaOH This titration consumes 11.1 mL of 0.121 M NaOH What is the weight percent of (NH4)2SO4 in the 0.475-g sample? 123 Oyster beds in the oceans require chloride ions for growth The minimum concentration is mg/L (8 parts per million) To analyze for the amount of chloride ion in a 50.0-mL sample of water, you add a few drops of aqueous potassium chromate and then titrate the sample with 25.60 mL of 0.001036 M silver nitrate The silver nitrate reacts with chloride ion, and, when the ion is completely removed, the silver nitrate reacts with potassium chromate to give a red precipitate (a) Write a balanced net ionic equation for the reaction of silver nitrate with chloride ions (b) Write a complete balanced equation and a net ionic equation for the reaction of silver nitrate with potassium chromate, indicating whether each compound is water-soluble or not (c) What is the concentration of chloride ions in the sample? Is it sufficient to promote oyster growth? C2H4 + Cl2 + Ca(OH)2  n C2H4O + CaCl2 + H2O Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179k C hapter Stoichiometry: Quantitative Information about Chemical Reactions 124 ▲ A compound consisting of yttrium(III) ions, barium(II) ions, both copper(II) and copper(III) ions, and oxide ions is a superconducting material at low temperatures (page 135) It has the formula YBa2Cu3O7−x where x is a variable between and To find out the value of x, you dissolve 34.02 mg of the compound in mL of 1.0 M HCl Bubbles of oxygen gas (O2) are observed as the following reaction occurs: YBa2Cu3O7−x(s) + 13 H+(aq) n  Y3+(aq) + Ba2+(aq) + Cu2+(aq)  + 1/4(1 − 2x) O2(g) + 13/2 H2O(ℓ) You then boil the solution, cool it, and add 10 mL of 0.70 M KI under argon The following reaction occurs: Cu2+(aq) + I−(aq) n CuI(s) + I3−(aq) When this reaction is complete, a titration of the resulting solution with sodium thiosulfate requires 1.542 × 10−4 mol S2O32−(aq) I3−(aq) + S2O32−(aq) n I−(aq) + S4O62−(aq) What is the value of x in YBa2Cu3O7−x? 125 You wish to determine the weight percent of copper in a copper-containing alloy After dissolving a 0.251-g sample of the alloy in acid, an excess of KI is added, and the Cu2+ and I− ions undergo the reaction Cr(NH3)xCl3(aq) + x HCl(aq) n  x NH4+(aq) + Cr3+(aq) + (x + 3) Cl−(aq) Assume that 24.26 mL of 1.500 M HCl is used to titrate 1.580 g of Cr(NH3)xCl3 What is the value of x? 128 ▲ Thioridazine, C21H26N2S2, is a pharmaceutical agent used to regulate dopamine (Dopamine, a neurotransmitter, affects brain processes that control movement, emotional response, and ability to experience pleasure and pain.) A chemist can analyze a sample of the pharmaceutical for the thioridazine content by decomposing it to convert the sulfur in the compound to sulfate ion This is then “trapped” as water-insoluble barium sulfate (see Figure 4.4) SO42−(aq, from thioridazine) + BaCl2(aq) n BaSO4(s) + Cl−(aq) Suppose a 12-tablet sample of the drug yielded 0.301 g of BaSO4 What is the thioridazine content, in milligrams, of each tablet? 129 ▲ A herbicide contains 2,4-D (2,4-dichlorophenoxy­ acetic acid), C8H6Cl2O3 A 1.236-g sample of the herbicide was decomposed to liberate the chlorine as Cl− ion This was precipitated as AgCl, with a mass of 0.1840 g What is the mass percent of 2,4-D in the sample? OCH2CO2H Cu2+(aq) + I−(aq) n CuI(s) + I3−(aq) The liberated I3− is titrated with sodium thiosulfate according to the equation I3−(aq) + S2O32−(aq) n S4O62−(aq) + I−(aq) (a) Designate the oxidizing and reducing agents in the two reactions above (b) If 26.32 mL of 0.101 M Na2S2O3 is required for titration to the equivalence point, what is the weight percent of Cu in the alloy? 126 ▲ A compound has been isolated that can have either of two possible formulas: (a) K[Fe(C2O4)2(H2O)2] or (b) K3[Fe(C2O4)3] To find which is correct, you dissolve a weighed sample of the compound in acid, forming oxalic acid, H2C2O4 You then titrate this acid with potassium permanganate, KMnO4 (the source of the MnO4− ion) The balanced, net ionic equation for the titration is H2C2O4(aq) + MnO4−(aq) + H3O+(aq) n   Mn2+(aq) + 10 CO2(g) + 14 H2O(ℓ) Titration of 1.356 g of the compound requires 34.50 mL of 0.108 M KMnO4 Which is the correct formula of the iron-containing compound: (a) or (b)? 127 ▲ Chromium(III) chloride forms many compounds with ammonia To find the formula of one of these compounds, you titrate the NH3 in the compound with standardized acid H H C C C C C C Cl H Cl 2,4-D (2,4-dichlorophenoxyacetic acid) 130 ▲ Sulfuric acid is listed in a catalog with a concentration of 95–98% A bottle of the acid in the stockroom states that 1.00 L has a mass of 1.84 kg To determine the concentration of sulfuric acid in the stockroom bottle, a student dilutes 5.00 mL to 500 mL She then takes four 10.00-mL samples and titrates each with standardized sodium hydroxide (c = 0.1760 M) Sample 1 2 3 4 Volume NaOH (mL) 20.15 21.30 20.40 20.35 (a) What is the average concentration of the diluted sulfuric acid sample? (b) What is the mass percent of H2SO4 in the original bottle of the acid? 131 ▲ Anhydrous calcium chloride is a good drying agent because it will rapidly pick up water Suppose you have stored some carefully dried CaCl2 in a desiccator Unfortunately, someone did not close the top of the desiccator tightly, and the CaCl2 became partially Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179l Study Questions 133 ▲ Phosphate in urine can be determined by spectrophotometry After removing protein from the sample, it is treated with a molybdenum compound to give, ultimately, a deep blue polymolybdate The absorbance of the blue polymolybdate can be measured at 650 nm and is directly related to the urine phosphate concentration A 24-hour urine sample was collected from a patient; the volume of urine was 1122 mL The phosphate in a 1.00 mL portion of the urine sample was converted to the blue polymolybdate and diluted to 50.00 mL A calibration curve was prepared using phosphate-containing solutions (Concentrations are reported in grams of phosphorus (P) per liter of solution.) Solution (mass P/L) 1.00 × 10−6 g 2.00 × 10−6 g 3.00 × 10−6 g 4.00 × 10−6 g Urine sample Absorbance at 650 nm in a 1.0-cm cell 0.230 0.436 0.638 0.848 0.518 (a) What are the slope and intercept of the calibration curve? (b) What is the mass of phosphorus per liter of urine? (c) What mass of phosphate did the patient excrete in the one-day period? 134 ▲ A 4.000-g sample containing KCl and KClO4 was dissolved in sufficient water to give 250.00 mL of solution A 50.00-mL portion of the solution required 41.00 mL of 0.0750 M AgNO3 in a Mohr titration (page 172) Next, a 25.00-mL portion of the original solution was treated with V2(SO4)3 to reduce the perchlorate ion to chloride, V3+(aq) + ClO4−(aq) + 12 H2O(ℓ) n Cl−(aq) + VO2+(aq) + H3O+(aq) Summary and Conceptual Questions The following questions may use concepts from this and previous chapters 135 Two beakers sit on a balance; the total mass is 167.170 g One beaker contains a solution of KI; the other contains a solution of Pb(NO3)2 When the solution in one beaker is poured completely into the other, the following reaction occurs: KI(aq) + Pb(NO3)2(aq) n KNO3(aq) + PbI2(s) Photos: © Cengage Learning/ Charles D Winters 132 ▲ A 0.5510-g sample consisting of a mixture of iron and iron(III) oxide was dissolved completely in acid to give a solution containing iron(II) and iron(III) ions A reducing agent was added to convert all of the iron to iron(II) ions, and the solution was then titrated with the standardized KMnO4 (0.04240 M); 37.50 mL of the KMnO4 solution was required Calculate the mass percent of Fe and Fe2O3 in the 0.5510-g sample (Example 4.13 gives the equation for the reaction of iron(II) ions and KMnO4.) and the resulting solution was titrated with AgNO3 This titration required 38.12 mL of 0.0750 M AgNO3 What is the mass percent of KCl and KClO4 in the mixture? Solutions of KI and Pb(NO3)2 before reaction Solutions after reaction What is the total mass of the beakers and solutions after reaction? Explain completely 136 ▲ A weighed sample of iron (Fe) is added to liquid bromine (Br2) and allowed to react completely The reaction produces a single product, which can be isolated and weighed The experiment was repeated a number of times with different masses of iron but with the same mass of bromine (see graph below) 12 Mass of product (g) hydrated A 150-g sample of this partially hydrated material was dissolved in 80 g of hot water When the solution was cooled to 20 °C, 74.9 g of CaCl2 ⋅ H2O precipitated Knowing the solubility of calcium chloride in water at 20 °C is 74.5 g CaCl2/100 g water, determine the water content of the 150-g sample of partially hydrated calcium chloride (in moles of water per mole of CaCl2) 10 0 Mass of Fe (g) (a) What mass of Br2 is used when the reaction consumes 2.0 g of Fe? (b) What is the mole ratio of Br2 to Fe in the reaction? (c) What is the empirical formula of the product? (d) Write the balanced chemical equation for the reaction of iron and bromine (e) What is the name of the reaction product? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it C hapter Stoichiometry: Quantitative Information about Chemical Reactions (f) Which statement or statements best describe the experiments summarized by the graph? (i) When 1.00 g of Fe is added to the Br2, Fe is the limiting reagent (ii) When 3.50 g of Fe is added to the Br2, there is an excess of Br2 (iii) When 2.50 g of Fe is added to the Br2, both reactants are used up completely (iv) When 2.00 g of Fe is added to the Br2, 10.8 g of product is formed The percent yield must therefore be 20.0% 138 The reaction of aluminum and bromine is pictured below The white solid on the lip of the beaker at the end of the reaction is Al2Br6 In the reaction pictured below, which was the limiting reactant, Al or Br2? Photos: © Cengage Learning/Charles D Winters 179m 137 Let us explore a reaction with a limiting reactant Here, zinc metal is added to a flask containing aqueous HCl, and H2 gas is a product Zn(s) + HCl(aq) n ZnCl2(aq) + H2(g) © Cengage Learning/Charles D Winters The three flasks each contain 0.100 mol of HCl Zinc is added to each flask in the following quantities Flask 1: 7.00 g Zn Flask 2: 3.27 g Zn Flask 3: 1.31 g Zn When the reactants are combined, the H2 inflates the balloon attached to the flask The results are as follows: Flask 1: Balloon inflates completely, but some Zn remains when inflation ceases Flask 2: Balloon inflates completely No Zn remains Flask 3: Balloon does not inflate completely No Zn remains Before reaction After reaction 139 ▲ Two students titrate different samples of the same solution of HCl using 0.100 M NaOH solution and phenolphthalein indicator (Figure 4.12) The first student pipets 20.0 mL of the HCl solution into a flask, adds 20 mL of distilled water and a few drops of phenolphthalein solution, and titrates until a lasting pink color appears The second student pipets 20.0 mL of the HCl solution into a flask, adds 60 mL of distilled water and a few drops of phenolphthalein solution, and titrates to the first lasting pink color Each student correctly calculates the molarity of an HCl solution What will the second student’s result be? (a) four times less than the first student’s result (b) four times greater than the first student’s result (c) two times less than the first student’s result (d) two times greater than the first student’s result (e) the same as the first student’s result 140 In most states, a person will receive a “driving while intoxicated” (DWI) ticket if the blood alcohol level (BAL) is 80 mg per deciliter (dL) of blood or higher Suppose a person is found to have a BAL of 0.033 mol of ethanol (C2H5OH) per liter of blood Will the person receive a DWI ticket? Explain these results Perform calculations that support your explanation Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it 179n Study Questions 141 ATOM ECONOMY: Benzene, C6H6, is a common compound, and it can be oxidized to give maleic anhydride, C4H2O3, which is used in turn to make other important compounds H H H C C C C H 142 ATOM ECONOMY: Maleic anhydride, C4H2O3, can be produced by the oxidation of benzene (Study Question 141) It can also be produced from the oxidation of butene O O C C H H + 9/2 O2 H H C C H C O + CO2 + H2O C O (a) What is the % atom economy for the synthesis of maleic anhydride from benzene by this reaction? (b) If 972 g of maleic anhydride is produced from exactly 1.00 kg of benzene, what is the percent yield of the anhydride? What mass of the byproduct CO2 is also produced? H2C CH CH2 CH3 + O2 H C C C O + H2O C O (a) What is the % atom economy for the synthesis of maleic anhydride from butene by this reaction? (b) If 1.02 kg of maleic anhydride is produced from exactly 1.00 kg of butene, what is the percent yield of the anhydride? What mass of the byproduct H2O is also produced? Unless otherwise noted, all art on this page is © Cengage Learning 2015 Copyright 2015 Cengage Learning All Rights Reserved May not be copied, scanned, or duplicated, in whole or in part Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s) Editorial review has deemed that any suppressed content does not materially affect the overall learning experience Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it ... right) John Kotz, John Townsend, David Treichel, led to more than 170 papers istry & Chemical Reactivity, Paul Treichel in scientific journals He may and The Chemical World) as be contacted by email... subsequent rights restrictions require it Chemistry & Chemical Reactivity, Ninth Edition John C Kotz, Paul M Treichel, John R Townsend, and David A Treichel Product Director: Mary Finch Product... contacted by email at treichelpaul@me.com well as the General Chemistry Interactive CD-ROM His research on organometallic chemistry and electrochemistry John R Townsend, Professor of Chemistry at has