Preview chemistry, 8th edition by robert c fay john mcmurry jill k robinson (2020)

Preview Chemistry, 8th Edition by Robert C. Fay John McMurry Jill K. Robinson (2020) Preview Chemistry, 8th Edition by Robert C. Fay John McMurry Jill K. Robinson (2020) Preview Chemistry, 8th Edition by Robert C. Fay John McMurry Jill K. Robinson (2020) Preview Chemistry, 8th Edition by Robert C. Fay John McMurry Jill K. Robinson (2020) Preview Chemistry, 8th Edition by Robert C. Fay John McMurry Jill K. Robinson (2020)

List of the Elements with Their Atomic Symbols and Atomic Weights Name Symbol Atomic Atomic Number Weight Actinium Ac 89 (227)* Aluminum Al 13 26.981538 Americium Am 95 (243) Antimony Sb 51 121.760 Argon Ar 18 39.948 Arsenic As 33 74.92160 Astatine At 85 (210) Barium Ba 56 137.327 Berkelium Bk 97 (247) Beryllium Be 4 9.012182 Bismuth Bi 83 208.98040 Bohrium Bh 107 (272) Boron B 5 10.811 Bromine Br 35 79.904 Cadmium Cd 48 112.411 Calcium Ca 20 40.078 Californium Cf 98 (251) Carbon C 12.0107 Cerium Ce 58 140.116 Cesium Cs 55 132.90545 Chlorine Cl 17 35.453 Chromium Cr 24 51.9961 Cobalt Co 27 58.933195 Copernicium Cn 112 (285) Copper Cu 29 63.546 Curium Cm 96 (247 ) Darmstadtium Ds 110 (281) Dubnium Db 105 (268) Dysprosium Dy 66 162.500 Einsteinium Es 99 (252) Erbium Er 68 167.259 Europium Eu 63 151.964 Fermium Fm 100 (257) Flerovium Fl 114 (289) Fluorine F 9 18.998403 Francium Fr 87 (223) Gadolinium Gd 64 157.25 Gallium Ga 31 69.723 Germanium Ge 32 72.64 Gold Au 79 196.96657 Hafnium Hf 72 178.49 Hassium Hs 108 (270) a Helium He 2 4.002602 Holmium Ho 67 164.93032 Hydrogen H 1 1.00794 Indium In 49 114.818 Iodine I 53 126.90447 Iridium Ir 77 192.217 Iron Fe 26 55.845 Krypton Kr 36 83.798 Lanthanum La 57 138.9055 Lawrencium Lr 103 (262) Lead Pb 82 207.2 Lithium Li 3 6.941 Livermorium Lv 116 (293) Lutetium Lu 71 174.9668 Magnesium Mg 12 24.3050 Manganese Mn 25 54.938045 Meitnerium Mt 109 (276) Atomic Atomic Name Symbol Number Weight Mendelevium Md 101 (258) Mercury Hg 80 200.59 Molybdenum Mo 42 95.96 Moscovium Mc 115 (288) Neodymium Nd 60 144.242 Neon Ne 10 20.1797 Neptunium Np 93 (237) Nickel Ni 28 58.6934 Nihonium Nh 113 (284) Niobium Nb 41 92.90638 Nitrogen N 7 14.0067 Nobelium No 102 (259) Oganesson Og 118 (294) Osmium Os 76 190.23 Oxygen O 8 15.9994 Palladium Pd 46 106.42 Phosphorus P 15 30.973762 Platinum Pt 78 195.094 Plutonium Pu 94 (244) Polonium Po 84 (209) Potassium K 19 39.0983 Praseodymium Pr 59 140.90765 Promethium Pm 61 (145) Protactinium Pa 91 231.03588 Radium Ra 88 (226) Radon Rn 86 (222) a Rhenium Re 75 186.207 Rhodium Rh 45 102.90550 Roentgenium Rg 111 (280) Rubidium Rb 37 85.4678 Ruthenium Ru 44 101.07 Rutherfordium Rf 104 (265) Samarium Sm 62 150.36 Scandium Sc 21 44.955912 Seaborgium Sg 106 (271) Selenium Se 34 78.96 Silicon Si 14 28.0855 Silver Ag 47 107.8682 Sodium Na 11 22.989769 Strontium Sr 38 87.62 Sulfur S 16 32.065 Tantalum Ta 73 180.9479 Technetium Tc 43 (98) Tellurium Te 52 127.60 Tennessine Ts 117 (292) Terbium Tb 65 158.92535 Thallium Tl 81 204.3833 Thorium Th 90 232.0381 Thulium Tm 69 168.93421 Tin Sn 50 118.710 Titanium Ti 22 47.867 Tungsten W 74 183.84 Uranium U 92 238.02891 Vanadium V 23 50.9415 Xenon Xe 54 131.293 Ytterbium Yb 70 173.054 Yttrium Y 39 88.90585 Zinc Zn 30 65.38 Zirconium Zr 40 91.224 *Values in parentheses are the mass numbers of the most common or longest lived isotopes of radioactive elements CVR_MCMU6230_08_SE_FEP.indd 04/12/2018 09:47 CVR_MCMU6230_08_SE_FEP.indd 04/12/2018 09:47 137.327 88 Ra (226) 87 Fr (223) (265) 57 La (262) Lanthanide series Actinide series 58 Ce 104 Rf 103 Lr (227) 89 Ac 138.9055 (268) 178.49 174.9668 59 Pr (271) 106 Sg 183.84 91 Pa 92 U 144.242 60 Nd (272) 107 Bh 186.207 75 Re (98) 232.0381 231.03588 238.02891 90 Th 140.116 140.90765 105 Db 180.9479 74 W 95.96 (237) 93 Np (145) 61 Pm (270) 108 Hs 190.23 76 Os 101.07 44 Ru (244) 94 Pu 150.36 62 Sm (276) 109 Mt 192.217 77 Ir 102.90550 45 Rh (243) 95 Am 151.964 63 Eu (281) 110 Ds 195.094 78 Pt 106.42 46 Pd 58.933195 58.6934 (247) 96 Cm 157.25 64 Gd (280) 111 Rg 196.96657 79 Au 107.8682 47 Ag 63.546 66 Dy (284) 113 Nh 204.3833 81 Tl 114.818 49 In 69.723 31 Ga 67 Ho (289) 114 FL 207.2 82 Pb 118.710 50 Sn 72.64 32 Ge 68 Er (288) 115 Mc 208.98040 83 Bi 121.760 51 Sb 74.92160 33 As 26.981538 28.0855 30.973762 15 P 14.0067 N 15 5A F 17 7A (247) 97 Bk (251) 98 Cf (252) 99 Es (257) 100 Fm 10 Ne 4.002602 He 18 8A 69 Tm (293) 116 Lv (209) 84 Po 127.60 52 Te 78.96 34 Se 32.065 16 S (258) 101 Md 54 Xe 83.798 36 Kr 39.948 18 Ar 70 Yb (292) 117 Ts (210) 85 At (259) 102 No (294) 118 Og (222) 86 Rn 126.90447 131.293 53 I 79.904 35 Br 35.453 17 Cl 15.9994 18.998403 20.1797 O 16 6A Main groups 158.92535 162.500 164.93032 167.259 168.93421 173.054 65 Tb (285) 112 Cn 200.59 80 Hg 112.411 48 Cd 65.38 30 Zn 132.90545 73 Ta 72 Hf 71 Lu 92.90638 91.224 88.90585 43 Tc 29 Cu 56 Ba 42 Mo 28 Ni 87.62 26 Fe 51.9961 54.938045 55.845 25 Mn 27 Co 55 Cs 40 Zr 39 Y 24 Cr 85.4678 50.9415 47.867 44.955912 41 Nb 23 V 22 Ti 21 Sc 38 Sr 12 2B 40.078 11 1B 37 Rb 10 39.0983 8B 20 Ca 24.3050 7B 19 K 6B 22.989769 5B 4B 3B 14 Si 11 Na 12.0107 12 Mg 6.941 13 Al 9.012182 Li 10.811 C B Be 1.00794 Transition metals 14 4A 13 3A 2A H 1A Main groups Periodic Table of the Elements CHEMISTRY E I G H T H JILL K ROBINSON Indiana University JOHN E MCMURRY Cornell University ROBERT C FAY Cornell University E D I T I O N Director of Portfolio Management: Jeanne Zalesky Executive Courseware Portfolio Manager: Terry Haugen Content Producer: Shercian Kinosian Managing Producer: Kristen Flathman Courseware Director, Content Development: Barbara Yien Courseware Analysts: Cathy Murphy, Coleen Morrison, Jay McElroy Courseware Editorial Assistant: Harry Misthos Rich Media Content Producers: Jenny Moryan, Ziki Dekel Director MasteringChemistry Content Development: Amir Said MasteringChemistry Senior Content Producer: Margaret Trombley MasteringChemistry Content Producers: Meaghan Fallano, Kaitlin Smith Full-Service Vendor, Project Manager: Pearson CSC, Kelly Murphy Copyeditor: Pearson CSC Compositor: Pearson CSC Art House, Coordinator: Lachina, Rebecca Marshall Design Manager: Maria Guglielmo Walsh Interior & Cover Designer: Gary Hespeneide Rights & Permissions Manager: Ben Ferrini Rights & Permissions Project Manager: Pearson CSC, Eric Schrader Rights & Permissions Specialist/Photo Researcher: Pearson CSC, Angelica Aranas Manufacturing Buyer: Stacey Weinberger VP, Director of Field Marketing: Tim Galligan Director of Product Marketing: Allison Rona Executive Field Marketing Manager: Christopher Barker Senior Product Marketing Manager: Elizabeth Bell Cover Photo Credit: Beauty of Science/Science Source Copyright © 2020, 2016, 2012 by Pearson Education, Inc 221 River Street, Hoboken, NJ 07030 All Rights Reserved Printed in the United States of America This publication is protected by copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise For information regarding permissions, request forms and the appropriate contacts within the Pearson Education Global Rights & Permissions department Attributions of third party content appear on page C-1, which constitutes an extension of this copyright page PEARSON, ALWAYS LEARNING, Mastering™ Chemistry, and Learning Catalytics™ are exclusive trademarks in the U.S and/or other countries owned by Pearson Education, Inc or its affiliates Unless otherwise indicated herein, any third-party trademarks that may appear in this work are the property of their respective owners and any references to third-party trademarks, logos or other trade dress are for demonstrative or descriptive purposes only Such references are not intended to imply any sponsorship, endorsement, authorization, or promotion of Pearson's products by the owners of such marks, or any relationship between the owner and Pearson Education, Inc or its affiliates, authors, licensees or distributors Library of Congress Cataloging-in-Publication Data Names: Robinson, Jill K | McMurry, John | Fay, Robert C., 1936Title: Chemistry / Jill K Robinson (Indiana University), John E McMurry (Cornell University), Robert C Fay (Cornell University) Description: Eighth edition | Hoboken, NJ : Pearson Education, Inc., [2020] Identifiers: LCCN 2018053050 | ISBN 9780134856230 (casebound) Subjects: LCSH: Chemistry Textbooks Classification: LCC QD33.2 M36 2020 | DDC 540 dc23 LC record available at https://lccn.loc.gov/2018053050 1  19 www.pearson.com ISBN 10: 0-134-85623-6 ISBN 13: 978-0-134-85623-0 (Student edition) ISBN 10: 0-135-21012-7 ISBN 13:978-0-135-21012-3 (Looseleaf Edition) Brief Contents Preface xiii For Instructors  xvi 1 Chemical Tools: Experimentation and Measurement  2 Atoms, Molecules, and Ions  33 3 Mass Relationships in Chemical Reactions  83 4 Reactions in Aqueous Solution  116 5 Periodicity and the Electronic Structure of Atoms  161 6 Ionic Compounds: Periodic Trends and Bonding Theory  208 7 Covalent Bonding and Electron-Dot Structures  238 8 Covalent Compounds: Bonding Theories and Molecular Structure  278 9 Thermochemistry: Chemical Energy  327 10 Gases: Their Properties and Behavior  374 11 Liquids and Phase Changes  422 12 Solids and Solid-State Materials  450 13 Solutions and Their Properties  494 14 Chemical Kinetics  538 15 Chemical Equilibrium  601 16 Aqueous Equilibria: Acids and Bases  654 17 Applications of Aqueous Equilibria  708 18 Thermodynamics: Entropy, Free Energy, and Spontaneity  768 19 Electrochemistry 813 20 Nuclear Chemistry  870 21 Transition Elements and Coordination Chemistry  904 22 The Main-Group Elements  954 23 Organic and Biological Chemistry  1003 iii Contents Preface xiii For Instructors  xvi 2.12 Ions and Ionic Bonds  61 2.13 Naming Chemical Compounds  63 INQUIRY Chemical Tools: Experimentation and Measurement 1 The Scientific Method: Nanoparticle Catalysts for Fuel Cells 2 1.2 Measurements: SI Units and Scientific Notation  1.3 Mass and Its Measurement  1.4 Length and Its Measurement  1.5 Temperature and Its Measurement  1.6 Derived Units: Volume and Its Measurement  11 1.7 Derived Units: Density and Its Measurement  13 1.8 Derived Units: Energy and Its Measurement  14 1.9 Accuracy, Precision, and Significant Figures in Measurement  16 1.10 Significant Figures in Calculations  18 1.11 Converting from One Unit to Another  20 1.1 INQUIRY  hat are the unique properties of nanoscale W materials? 23 Study Guide • Key Terms • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Mass Relationships in Chemical Reactions 83 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Chemistry and the Elements  34 Elements and the Periodic Table  36 Some Common Groups of Elements and Their Properties 38 2.4 Observations Supporting Atomic Theory: The Conservation of Mass and the Law of Definite Proportions 41 2.5 The Law of Multiple Proportions and Dalton’s Atomic Theory 43 2.6 Atomic Structure: Electrons  45 2.7 Atomic Structure: Protons and Neutrons  47 2.8 Atomic Numbers  49 2.9 Atomic Weights and the Mole  51 2.10 Measuring Atomic Weight: Mass Spectrometry  55 2.11 Mixtures and Chemical Compounds; Molecules and Covalent Bonds  57 Representing Chemistry on Different Levels  84 Balancing Chemical Equations  85 Molecular Weight and Molar Mass  88 Stoichiometry: Relating Amounts of Reactants and Products  90 Yields of Chemical Reactions  92 Reactions with Limiting Amounts of Reactants  94 Percent Composition and Empirical Formulas  97 Determining Empirical Formulas: Elemental Analysis 100 Determining Molecular Weights: Mass Spectrometry 103 INQUIRY  ow is the principle of atom economy H used to minimize waste in a chemical synthesis? 105 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Atoms, Molecules, and Ions 33 2.1 2.2 2.3  ow can measurements of oxygen H and hydrogen isotopes in ice cores determine past climates?  69 Reactions in Aqueous Solution 116 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Solution Concentration: Molarity  117 Diluting Concentrated Solutions  119 Electrolytes in Aqueous Solution  121 Types of Chemical Reactions in Aqueous Solution 123 Aqueous Reactions and Net Ionic Equations  124 Precipitation Reactions and Solubility Guidelines 125 Acids, Bases, and Neutralization Reactions  128 Solution Stoichiometry  132 Measuring the Concentration of a Solution: Titration 133 4.10 4.11 4.12 4.13 4.14 Contents Oxidation–Reduction (Redox) Reactions  135 Identifying Redox Reactions  138 The Activity Series of the Elements  141 Redox Titrations  144 Some Applications of Redox Reactions  146 INQUIRY Periodicity and the Electronic Structure of Atoms 161 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 Wave Properties of Radiant Energy and the Electromagnetic Spectrum  162 Particlelike Properties of Radiant Energy: The Photoelectric Effect and Planck’s Postulate  166 Atomic Line Spectra and Quantized Energy  169 Wavelike Properties of Matter: de Broglie’s Hypothesis 173 The Quantum Mechanical Model of the Atom: Heisenberg’s Uncertainty Principle  175 The Quantum Mechanical Model of the Atom: Orbitals and Quantum Numbers  176 The Shapes of Orbitals  179 Electron Spin and the Pauli Exclusion Principle  184 Orbital Energy Levels in Multielectron Atoms  185 Electron Configurations of Multielectron Atoms  187 Anomalous Electron Configurations  189 Electron Configurations and the Periodic Table  189 Electron Configurations and Periodic Properties: Atomic Radii  192 INQUIRY  ow does knowledge of atomic emission H spectra help us build more efficient light bulbs? 195 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Ionic Compounds: Periodic Trends and Bonding Theory 208 6.1 6.2 6.3 6.4 Electron Configurations of Ions  209 Ionic Radii  212 Ionization Energy  214 Higher Ionization Energies  216 Electron Affinity  218 The Octet Rule  220 Ionic Bonds and the Formation of Ionic Solids  222 Lattice Energies in Ionic Solids  226 INQUIRY  ow sports drinks replenish H the substances lost in sweat?  148 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 5.1 6.5 6.6 6.7 6.8 v  ow ionic liquids lead to more H environmentally friendly processes?  228 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Covalent Bonding and Electron-Dot Structures 238 Covalent Bonding in Molecules  239 Strengths of Covalent Bonds  240 Polar Covalent Bonds: Electronegativity  242 A Comparison of Ionic and Covalent Compounds  246 Electron-Dot Structures: The Octet Rule  247 Procedure for Drawing Electron-Dot Structures  250 Drawing Electron-Dot Structures for Radicals  254 Electron-Dot Structures of Compounds Containing Only Hydrogen and Second-Row Elements  255 7.9 Electron-Dot Structures and Resonance  257 7.10 Formal Charges  261 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 INQUIRY  ow does bond polarity affect the toxicity H of organophosphate insecticides?  265 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Covalent Compounds: Bonding Theories and Molecular Structure 278 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 Molecular Shapes: The VSEPR Model  279 Valence Bond Theory  286 Hybridization and sp3 Hybrid Orbitals  287 Other Kinds of Hybrid Orbitals  290 Polar Covalent Bonds and Dipole Moments  295 Intermolecular Forces  298 Molecular Orbital Theory: The Hydrogen Molecule  306 Molecular Orbital Theory: Other Diatomic Molecules 308 Combining Valence Bond Theory and Molecular Orbital Theory  312 INQUIRY  hich is better for human health, natural or W ­synthetic vitamins?  314 Study Guide • Key Terms • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems vi Contents Thermochemistry: Chemical Energy 327 Energy and Its Conservation  328 Internal Energy and State Functions  330 Expansion Work  332 Energy and Enthalpy  334 Thermochemical Equations and the Thermodynamic Standard State  336 9.6 Enthalpies of Chemical and Physical Changes  338 9.7 Calorimetry and Heat Capacity  341 9.8 Hess’s Law  345 9.9 Standard Heats of Formation  348 9.10 Bond Dissociation Energies  350 9.11 An Introduction to Entropy  352 9.12 An Introduction to Free Energy  355 11.4 Energy Changes during Phase Transitions  431 11.5 Phase Diagrams  433 11.6 Liquid Crystals  436 9.1 9.2 9.3 9.4 9.5 INQUIRY  ow we determine the energy content H of biofuels?  359 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 10 Gases: Their Properties and Behavior 374 Gases and Gas Pressure  375 The Gas Laws  380 The Ideal Gas Law  385 Stoichiometric Relationships with Gases  387 Mixtures of Gases: Partial Pressure and Dalton’s Law 390 10.6 The Kinetic–Molecular Theory of Gases  393 10.7 Gas Diffusion and Effusion: Graham’s Law  395 10.8 The Behavior of Real Gases  397 10.9 The Earth’s Atmosphere and the Greenhouse Effect 398 10.10 Greenhouse Gases  401 10.11 Climate Change  403 10.1 10.2 10.3 10.4 10.5 INQUIRY How inhaled anesthetics work?  407 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 11 Liquids and Phase Changes 422 11.1 Properties of Liquids  423 11.2 Vapor Pressure and Boiling Point  424 11.3 Phase Changes between Solids, Liquids, and Gases  428 INQUIRY How is caffeine removed from coffee?  439 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 12 Solids and Solid-State Materials 450 12.1 Types of Solids  451 12.2 Probing the Structure of Solids: X-Ray Crystallography 453 12.3 The Packing of Spheres in Crystalline Solids: Unit Cells  455 12.4 Structures of Some Ionic Solids  459 12.5 Structures of Some Covalent Network Solids  462 12.6 Bonding in Metals  464 12.7 Semiconductors 468 12.8 Semiconductor Applications  471 12.9 Superconductors 475 12.10 Ceramics and Composites  477 INQUIRY  hat are quantum dots, and what controls W their color?  482 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 13 Solutions and Their Properties 494 Solutions 495 Enthalpy Changes and the Solution Process  496 Predicting Solubility  498 Concentration Units for Solutions  501 Some Factors That Affect Solubility  506 Physical Behavior of Solutions: Colligative Properties 510 13.7 Vapor-Pressure Lowering of Solutions: Raoult’s Law 511 13.8 Boiling-Point Elevation and Freezing-Point Depression of Solutions  517 13.9 Osmosis and Osmotic Pressure  521 13.1 13.2 13.3 13.4 13.5 13.6 INQUIRY  ow does hemodialysis cleanse the blood H of patients with kidney failure?  525 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems Contents 14 Chemical Kinetics 538 14.1 Reaction Rates  539 14.2 Rate Laws and Reaction Order  544 14.3 Method of Initial Rates: Experimental Determination of a Rate Law  546 14.4 Integrated Rate Law: Zeroth-Order Reactions  550 14.5 Integrated Rate Law: First-Order Reactions  552 14.6 Integrated Rate Law: Second-Order Reactions  557 14.7 Reaction Rates and Temperature: The Arrhenius Equation 560 14.8 Using the Arrhenius Equation  564 14.9 Reaction Mechanisms  567 14.10 Rate Laws for Elementary Reactions  570 14.11 Rate Laws for Overall Reactions  573 14.12 Catalysis 577 14.13 Homogeneous and Heterogeneous Catalysts  580 INQUIRY How enzymes work?  583 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 15 Chemical Equilibrium 601 The Equilibrium State  603 The Equilibrium Constant Kc 605 The Equilibrium Constant KP 610 Heterogeneous Equilibria  612 Using the Equilibrium Constant  614 Factors That Alter the Composition of an Equilibrium Mixture: Le Châtelier’s Principle  624 15.7 Altering an Equilibrium Mixture: Changes in Concentration  625 15.8 Altering an Equilibrium Mixture: Changes in Pressure and Volume  629 15.9 Altering an Equilibrium Mixture: Changes in Temperature  631 15.10 The Link between Chemical Equilibrium and Chemical Kinetics  634 15.1 15.2 15.3 15.4 15.5 15.6 INQUIRY  ow does high altitude affect oxygen H transport in the body?  637 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems vii Dissociation of Water  664 The pH Scale  666 Measuring pH  668 The pH in Solutions of Strong Acids and Strong Bases 669 16.8 Equilibria in Solutions of Weak Acids  671 16.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids  673 16.10 Percent Dissociation in Solutions of Weak Acids  677 16.11 Polyprotic Acids  678 16.12 Equilibria in Solutions of Weak Bases  682 16.13 Relation Between Ka and Kb 684 16.14 Acid–Base Properties of Salts  686 16.15 Lewis Acids and Bases  691 16.4 16.5 16.6 16.7 INQUIRY  as the problem of acid rain been H solved? 694 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 17 Applications of Aqueous Equilibria 708 17.1 Neutralization Reactions  709 17.2 The Common-Ion Effect  712 17.3 Buffer Solutions  716 17.4 The Henderson–Hasselbalch Equation  720 17.5 pH Titration Curves  723 17.6 Strong Acid–Strong Base Titrations  724 17.7 Weak Acid–Strong Base Titrations  727 17.8 Weak Base–Strong Acid Titrations  732 17.9 Polyprotic Acid–Strong Base Titrations  733 17.10 Solubility Equilibria for Ionic Compounds  738 17.11 Measuring Ksp and Calculating Solubility from Ksp 739 17.12 Factors That Affect Solubility  742 17.13 Precipitation of Ionic Compounds  750 17.14 Separation of Ions by Selective Precipitation  751 17.15 Qualitative Analysis  752 INQUIRY What is causing ocean acidification?  754 Study Guide • Key Terms • Key Equations • Practice Test • Conceptual Problems • Section Problems • Multiconcept Problems 16 Aqueous Equilibria: Acids and Bases 654 18 Thermodynamics: Entropy, Free Energy, and Spontaneity 768 16.1 Acid–Base Concepts: The Brønsted–Lowry Theory  655 16.2 Acid Strength and Base Strength  658 16.3 Factors That Affect Acid Strength  661 18.1 Spontaneous Processes  769 18.2 Enthalpy, Entropy, and Spontaneous Processes  770 18.3 Entropy and Probability  773 146     chapter    Reactions in Aqueous Solution STRATEGY The procedure is similar to that outlined in Figure 4.9 except that volume of the Na2S2O3 solution can be used to find moles of S2O32- instead of a gram-to-mole conversion SOLUTION We first need to find the number of moles of thiosulfate ion used for the titration: 24.55 mL * 0.102 mol S2O321L * = 2.50 * 10 -3 mol S2O321000 mL 1L According to the balanced equation, mol of S2O32- ion react with mol of I3- ion Thus, we can find the number of moles of I3- ion: 2.50 * 10 -3 mol S2O32- * - ▲▲ The reddish I3 solution turns a deep blue color when it is added to a solution containing a small amount of starch mol I32 mol S2O32- = 1.25 * 10 -3 mol I3- Knowing both the number of moles of I3-(1.25 * 10 -3 mol) and the volume of the I3solution (10.00 mL), let us calculate molarity: 1.25 * 10 -3 mol I3103 mL = 0.125 M * 1L 10.00 mL The molarity of the I3- solution is 0.125 M CHECK According to the balanced equation, the amount of S2O32- needed for the reaction (2 mol) is twice the amount of I3- (1 mol) The titration results indicate that the volume of the S2O32- solution (24.55 mL) is a little over twice the volume of the I3solution (10.00 mL) Thus, the concentrations of the two solutions must be about the same—approximately 0.1 M ▶▶PRACTICE 4.29  What is the molar concentration of Fe2+ ion in an aqueous solution if 31.50 mL of 0.105 M KBrO3 is required for complete reaction with 10.00 mL of the Fe2+ solution? The net ionic equation is: Fe2+(aq) + BrO3-(aq) + H + (aq) ¡ Fe3+(aq) + Br -(aq) + H2O(l) ▶▶APPLY 4.30  Iron(II) sulfate is a soluble ionic compound added as a source of iron in vitamin tablets Determine the mass of iron (mg) in one tablet that has been dissolved in 10.0 mL of water and titrated with 14.92 mL of 0.0100 M K2Cr2O7 solution The net ionic equation is: Cr2O72-(aq) + Fe2+(aq) + 14 H +(aq) ¡ Cr3+(aq) + Fe3+(aq) + H2O(l) 4.14  SOME APPLICATIONS OF REDOX REACTIONS Redox reactions take place with every element in the periodic table except helium and neon and occur in a vast number of processes throughout nature, biology, and industry Here are just a few examples: • Combustion Combustion is the burning of a fuel by oxidation with oxygen in air Gasoline, fuel oil, natural gas, wood, paper, and other organic substances of carbon and hydrogen are the most common fuels Even some metals, such as magnesium and calcium, will burn in air CH4(g) + O2(g) ¡ CO2(g) + H2O(l) Methane (Natural gas) • Bleaching Bleaching uses redox reactions to decolorize or lighten colored materials Dark hair is bleached to turn it blond, clothes are bleached to remove stains, 4.14  Some Applications of Redox Reactions      147 wood pulp is bleached to make white paper, and so on The exact oxidizing agent used depends on the situation—hydrogen peroxide (H2O2) is used for hair, sodium hypochlorite (NaOCl) is used for clothes, and ozone or chlorine dioxide is used for wood pulp—but the principle is always the same In all cases, colored impurities are destroyed by reaction with a strong oxidizing agent • Batteries Although they come in many types and sizes, all types of batteries are powered by redox reactions In a typical redox reaction carried out in the laboratory— say, the reaction of zinc metal with Ag+ to yield Zn2+ and silver metal—the reactants are simply mixed in a flask and electrons are transferred by direct­ contact between them In a battery, however, the two reactants are kept in separate compartments and the electrons are transferred through a wire running between them The inexpensive alkaline battery commonly used in flashlights and other small household items uses a thin steel can containing zinc powder and a paste of potassium hydroxide as one reactant, separated by paper from a paste of powdered carbon and manganese dioxide as the other reactant A graphite rod with a metal cap sticks into the MnO2 to provide electrical contact When the can and the graphite rod are connected by a wire, zinc sends electrons flowing through the wire toward the MnO2 in a redox reaction The resultant electrical current can be used to light a bulb or power a small electronic device The reaction is Zn(s) + MnO2(s) ¡ ZnO(s) + Mn2O3(s) We’ll look at the chemistry of batteries in more detail in Section 19.10 • Metallurgy Metallurgy, the extraction and purification of metals from their ores, makes use of numerous redox processes Metallic zinc is prepared by reduction of ZnO with coke, a form of carbon: ZnO(s) + C(s) ¡ Zn(s) + CO(g) • Corrosion Corrosion is the deterioration of a metal by oxidation, such as the rusting of iron in moist air The economic consequences of rusting are enormous: It has been estimated that up to one-fourth of the iron produced in the United States is used to replace bridges, buildings, and other structures that have been destroyed by corrosion (The raised dot in the formula Fe 2O3 # H2O for rust indicates that one water molecule is associated with each Fe 2O3 in an unspecified way.) Fe(s) + O2(g) ¡ Fe 2O3 # H2O(s) H2 O Rust • Respiration The term respiration refers to the processes of breathing and using oxygen for the many biological redox reactions that provide the energy needed by living organisms The energy is released from food molecules slowly and in complex, multi-step pathways, but the overall result of respiration is similar to that of a combustion reaction For example, the simple sugar glucose (C6H12O6) reacts with O2 to give CO2 and H2O according to the following equation: C6H12O6 + O2 S CO2 + H2O + energy Glucose (a carbohydrate) ▲▲ Dark hair can be bleached by a redox reaction with hydrogen peroxide 148     chapter INQUIRY    Reactions in Aqueous Solution How sports drinks replenish the substances lost in sweat? A thletes consume sports drinks, such as Gatorade and Powerade, during exercise How these drinks help them perform better and recover more quickly? Sports drinks were first developed in 1965 when University of F ­ lorida football coaches noted that players became extremely fatigued, lost significant amounts of weight, and seldom needed to urinate after exercising in the heat The team consulted with Robert Cade (1927–2007), a kidney specialist at the University of Florida’s College of Medicine, who speculated that electrolytes lost in sweat were upsetting the body’s delicate chemical balance Sodium and potassium ions were of primary concern due to their importance in nerve and muscle function, regulation of body heat, distribution of water, and transport of solutes such as glucose for energy To test his hypothesis, Cade and a team of researchers studied the fluids of freshman players before and after exercising vigorously in the heat The results were staggering; after exercise the players had an electrolyte imbalance, low blood sugar, and decreased total blood volume; leading to diminished physical performance and in some cases extreme heat exhaustion Cade's team created a drink to replace the fluids and electrolytes lost through sweat and the carbohydrates burned for energy The first batch contained water, salt, sugar, and lemon juice By 1966, the drink known as Gatorade became a staple for the team, and hospitalizations of players due to heat exhaustion became almost nonexistent The Gators advanced to the Orange Bowl for the first time in the school’s history The university released an official statement about Gatorade in late December 1966 that the Florida Times-Union summed up with this headline: “One Lil’ Swig of That Kickapoo Juice and Biff, Bam, Sock—It’s Gators, 8-2.” CO2H HO2C H C H C H C H H CO2H OH H H Citric acid (C6H8O7) C C C N C C CO2H H Vitamin B3 (C6NH5O2) H C H OH C O H H H C C C CH2OH OH OH OH Fructose (C6H12O6) PROBLEM 4.32  The nutritional label on Powerade specifies that there are 150 mg of sodium and 35 mg of potassium in 360 mL of the beverage Calculate the concentration of sodium and potassium ions in units of molarity PROBLEM 4.33  The concentration of sodium ions in Powerade is 0.416 mg/mL Imagine that you want to prepare your own drink with the same concentration of sodium ions How many grams of sodium chloride are needed to prepare 0.500 L of solution? PROBLEM 4.34  One way to analyze a sports drink for the con­ centration of chloride ions is to add silver ions and weigh the resulting AgCl precipitate One problem with the analysis is that many sports drinks contain phosphate ion (PO43-), which will also precipitate with silver, thus interfering with the chloride mea­ surement The phosphate ion can be removed by precipitation prior to the analysis of chloride (a) Use the solubility guidelines (Table 4.2) to choose a cation from the list below that would form a precipitate with phosphate but not with chloride K+ , Ba2+ , Pb2+ , NH4+ (b) Write the net ionic reaction for the precipitation reaction from part (a) ▲▲ Gatorade and other sports drinks contain electrolytes and conduct electricity PROBLEM 4.31  A vitamin-fortified brand of a sports beverage contains sodium chloride (NaCl), sodium citrate (NaC6H7O7), and potassium dihydrogen phosphate (KH2PO4) as well as the substances whose structures are given in the figure (a) Use Table 4.1 (Electrolyte Classification of Some Common Substances) to classify the components of the sports drink as a strong electrolyte, weak electrolyte, or nonelectrolyte (b) Identify which substances replenish electrolytes with important biological functions PROBLEM 4.35 To measure the concentration of chloride ions in a sports beverage, an excess of silver ions were added to 100.0 mL of the drink A white precipitate of silver chloride was isolated by filtration, dried, and found to have a mass of 172 mg Calculate the concentration of chloride ion in the drink in units of molarity PROBLEM 4.36  The flavor of the first batch of Gatorade was improved by adding lemon juice, which contains citric acid (H3C6H5O7) Citric acid is still added as flavoring to sports drinks today The concentration of citric acid in a beverage was determined by titration with sodium hydroxide according to the reaction: H3C6H5O7(aq) + NaOH(aq) ¡ Na3C6H5O7(aq) + H2O(l) If 25.0 mL of the beverage required 35.6 mL of 0.0400 M NaOH for a complete reaction, calculate the molarity of citric acid Study Guide     149 READY-TO-GO STUDY TOOLS in the Mastering Chemistry Study Area help you master the toughest topics in General Chemistry Problem-Solving videos and Practice Tests are all in one, easy to navigate place to help keep you focused and give you the support you need to succeed STUDY GUIDE Section Concept Summary Learning Objectives Test Your Understanding 4.1 Solution Concentration: Molarity The concentration of a substance in solution is usually expressed as molarity (M), defined as the number of moles of a substance (solute) dissolved per liter of solution A solution’s molarity acts as a conversion factor between solution volume and number of moles of solute, making it possible to carry out stoichiometry calculations on solutions 4.1 Calculate the molarity of a solution given the mass of solute and total volume Worked Example 4.1; Problems 4.1–4.2, 4.50–4.51 4.2 Calculate the a amount of solute in a given volume of solution with a known molarity Worked Example 4.2; Problems 4.3–4.4, 4.46, 4.53 4.3 Describe the proper technique for preparing solutions of known molarity Problems 4.55–4.56 When carrying out a dilution, only the volume is changed by adding solvent; the amount of solute is unchanged 4.4 Calculate the concentration of a solution that has been diluted Worked Example 4.3; Problems 4.5–4.6, 4.59–4.60 4.2 Diluting Concentrated Solutions 4.5 Describe the proper technique for diluting solutions Problems 4.60–4.61 4.3 Electrolytes in Aqueous Solution Many reactions take place in aqueous solution Substances whose aqueous solutions contain ions conduct electricity and are called electrolytes Ionic compounds, such as NaCl, and molecular compounds that dissociate substantially into ions when dissolved in water are strong electrolytes Substances that dissociate to only a small extent are weak electrolytes, and substances that not produce ions in aqueous solution are nonelectrolytes 4.6 Classify a substance as a strong, weak, or nonelectrolyte (Table 4.1) Problems 4.62–4.63 4.7 Calculate the concentration of ions in a strong electrolyte solution Worked Example 4.4; Problems 4.7–4.8, 4.68, 4.70 4.4 Types of Chemical Reactions in Aqueous Solution Aqueous reactions can be classified into three major groups Precipitation reactions occur when solutions of two ionic substances are mixed and a precipitate settles out of the solution Acid–base neutralization reactions occur when an acid is mixed with a base, yielding water and an ionic salt Oxidation–reduction reactions, or redox reactions, occur when one or more electrons are transferred between reaction partners 4.8 Classify a reaction as a precipitation, acid–base neutralization, or oxidation–reduction (redox) reaction Problems 4.72–4.73 4.5 Aqueous Reactions and Net Ionic Equations Aqueous ionic compounds exist as cations and anions in solution An ionic equation shows all the ions in a reaction, and a net ionic equation shows only the ions that take part in a reaction Spectator ions are present to balance charge but not take part in the chemical reaction 4.9 Write a net ionic equation and identify spectator ions given the molecular equation Worked Example 4.5; Problems 4.9–4.10, 4.74 4.6 Precipitation Reactions and Solubility Guidelines Solubility guidelines (Table 4.2) are used to predict which combinations of anions and cations in ionic compounds will be soluble and insoluble To predict whether a precipitate will form in a reaction, write the formula of possible products and determine solubility 4.10 Use the solubility guidelines to predict the solubility of an ionic compound in water Problems 4.76–4.77 4.11 Predict whether a precipitation reaction will occur and write the ionic and net ionic equations Worked Examples 4.6–4.7; Problems 4.11–4.14, 4.78, 4.80 4.7 Acids, Bases, and Neutralization Reactions An acid is a substance that dissociates in water to give hydrogen (H+) ions, and a base is a substance that dissociates to give hydroxide ions (OH-) The neutralization of a strong acid with a strong base can be written as a net ionic equation, in which nonparticipating, spectator ions are not specified: 4.12 Convert between name and formula for an acid Worked Example 4.8; Problems 4.15–4.16 4.13 Classify acids as strong or weak based on the molecular picture of dissociation Problem 4.40 4.14 Write the ionic equation and net ionic equation for an acid–base neutralization reaction Worked Example 4.9; Problems 4.17–4.18, 4.96, 4.98 + - H (aq) + OH (aq) ¡ H2O(l) 150     chapter    Reactions in Aqueous Solution Section Concept Summary Learning Objectives Test Your Understanding 4.8 Solution Stoichiometry Stoichiometry calculations are performed by relating amounts of reactants and products in a balanced equation in units of moles since stoichiometric coefficients refer to moles Molarity is a conversion factor between numbers of moles of solute and the volume of a solution 4.15 Convert between moles and volume using molarity in stoichiometry calculations Worked Example 4.10; Problems 4.19–4.20, 4.100–4.101 4.9 Measuring the Concentration of a Solution: Titration Titration is a technique used to find the exact concentration of a solution A fixed volume of solution with unknown concentration is added to a flask A solution with a known concentration (titrant) is added from a buret until the reaction is complete The measured volume of titrant and reaction stoichiometry are used to calculate the concentration of the solution in the flask 4.16 Determine the concentration of a solution using titration data Worked Example 4.11; Problems 4.21, 4.102–4.103 4.17 Interpret molecular representations of substances in solution in a titration procedure Problems 4.22, 4.42–4.43 4.10 Oxidation– Reduction (Redox) Reactions Oxidation is the loss of one or more electrons; a reduction is the gain of one or more electrons Redox reactions can be identified by assigning to each atom in a substance an oxidation number, which provides a measure of whether the atom is neutral, electron-rich, or electronpoor Comparing the oxidation numbers of an atom before and after reaction shows whether the atom has gained or lost electrons 4.18 Assign oxidation numbers to atoms in a compound Worked Example 4.12; Problems 4.23–4.24, 4.108, 4.110 4.11 Identifying Redox Reactions Oxidations and reductions must occur together Whenever one substance loses one or more electrons (is oxidized), another substance gains the electrons (is reduced) The substance that causes a reduction by giving up electrons is called a reducing agent The substance that causes an oxidation by accepting electrons is called an oxidizing agent The reducing agent is itself oxidized when it gives up electrons, and the oxidizing agent is itself reduced when it accepts electrons 4.19 Identify redox reactions, oxidizing agents, and reducing agents Worked Example 4.13; Problems 4.25–4.26, 4.118–4.119 4.12 The Activity Series of the Elements Among the simplest of redox processes is the reaction of an aqueous cation, usually a metal ion, with a free element to give a different ion and a different element Noting the results from a succession of different reactions makes it possible to organize an activity series, which ranks the elements in order of their reducing ability in aqueous solution 4.20 Use the location of elements in the periodic table and activity series to predict if a redox reaction will occur Worked Example 4.14; Problems 4.27–4.28, 4.45, 4.120 4.21 Develop an activity series and predict if a redox reaction will occur based on experimental data provided Problems 4.122–4.123 The concentration of an oxidizing agent or a reducing agent in solution can be determined by a redox titration 4.22 Use a redox titration to determine the concentration of an oxidizing or reducing agent in solution Worked Example 4.15; Problems 4.29, 4.124, 4.126, 4.132 4.13–4.14 Redox Titration and Applications of Redox Reactions KEY TERMS acid   128 acid–base neutralization  reaction   123 activity series   142 base   128 diprotic acid   128 dissociate   122 electrolyte   122 half-reaction   139 hydronium ion, H3O ∙    128 ionic equation   124 molarity (M)   117 molecular equation   124 monoprotic acid   128 net ionic equation   124 nonelectrolyte   122 oxidation   136 oxidation number   136 oxidation–reduction  reaction   124 oxidizing agent   139 oxoacid   129 precipitation reaction   123 redox reaction   124 reducing agent   150 reduction   136 salt   131 solubility   125 solute   117 spectator ion   124 strong acid   128 strong base   129 strong electrolyte   122 titration   133 triprotic acid   128 weak acid   128 weak base   129 weak electrolyte   122 Practice Test     151 KEY EQUATIONS • Molarity (Section 4.1) Moles of solute Molarity (M) = Liters of solution • Dilution (Section 4.2) Mi * Vi = Mf * Vf PRACTICE TEST After studying this chapter, you can assess your understanding with these practice test questions, which are correlated with chapter learning objectives If you answer a question incorrectly, refer to the learning objectives in the end-of-chapter Study Guide for assistance The Study Guide provides a conceptual summary, references a Worked Example to model how to solve the problem, and gives additional problems for more practice What is the molarity of a solution prepared by dissolving 10.19 g of ethanol (CH3CH2OH) in enough water to produce 250.0 mL of solution? (LO 4.1) (a) 0.8848 M (b) 18.08 M (c) 1.130 M (d) 0.01808 M What is the mass of chloride ions in 375.0 mL of solution with a magnesium chloride concentration of 0.250 M? (LO 4.2) (a) 3.32 g (b) 47.3 g (c) 23.6 g (d) 6.65 g What volume of a 2.00 M stock solution of NaOH is required to prepare 50.0 mL of 0.400 M NaOH? (LO 4.4) (a) 15.0 mL (b) 1.00 mL (c) 10.0 mL (d) 4.00 mL Refer to the figure to answer questions and The images are a molecular representation of three different substances, AX3, AY3, and AZ3, dissolved in water (Water molecules are omitted for clarity.) Which of the following substances will produce a solution that does not conduct electricity when it dissolves in water? (LO 4.6) (a) NaOH (b) HNO3 (c) Na2SO4 (d) CH3OH Which of the following solutions will not form a precipitate when added to 10 mL of 0.10 M KOH? (LO 4.10, 4.11) (a) 10 mL of 0.10 NH4Cl (b) 10 mL of 0.10 M PbSO4 (c) 10 mL of 0.10 M Fe(NO3)3 (d) 10 mL of 0.10 M AgCH3CO2 Write a net ionic equation for the reaction that occurs when 10 mL of 0.5 M ammonium carbonate is mixed with 10 mL of 0.5 M silver nitrate (LO 4.9, 4.11) (a) NH4+(aq) + NO3-(aq) ¡ NH4NO3(s) (b) Ag+(aq) + CO32 -(aq) ¡ AgCO3-(s) (c) Ag+(aq) + CO32 -(aq) ¡ Ag2CO3(s) (d) A net ionic reaction cannot be written because a reaction does not take place When 75.0 mL of a 0.100 M lead(II) nitrate solution is mixed with 100.0 mL of a 0.190 M potassium iodide solution, a yellow-orange precipitate of lead(II) iodide is formed What is the mass in grams of lead(II) iodide formed? Assume the reaction goes to completion (LO 4.11, 4.15) (a) 1.729 g (b) 3.458 g (c) 4.380 g (d) 8.760 g 10 What volume of 0.250 M HCl is needed to react completely with 25.00 mL of 0.375 M Na2CO3? (LO 4.15) HCl(aq) + Na2CO3(aq) ¡ NaCl(aq) + H2O(l) + CO2(g) AX3 AY3 AZ3 Which of the substances is the weakest electrolyte? (LO 4.6) (a) AX3 (b) AY3 (c) AZ3 (d) All of the substances are strong electrolytes What are the molar concentrations of A ions and X ions in a 0.500 M solution of AX3? (LO 4.7) (a) 0.500 M A and 0.500 M X (b) 0.500 M A and 0.167 M X (c) 1.500 M A and 0.500 M X (d) 0.500 M A and 1.500 M X (a) 75.0 mL (b) 18.8 mL (c) 37.5 mL (d) 33.3 mL 11 Succinic acid, an intermediate in the metabolism of food molecules, has a molecular weight of 118.1 When 1.926 g of succinic acid was dissolved in water and titrated, 65.20 mL of 0.5000 M NaOH solution was required to neutralize the acid How many acidic hydrogens are there in a molecule of succinic acid? (LO 4.16) (a) (b) (c) (d) 12 Assign oxidation numbers to each atom in Borax, Na2B4O7, a mineral used in laundry detergent (LO 4.18) Na B O (a) +2 +3 -2 (b) -1 -3 +2 (c) +1 +3 -2 (d) +1 +2 -1 152     chapter    Reactions in Aqueous Solution 13 Identify the element that gets oxidized and the oxidizing agent in the reaction (LO 4.19) HCrO4-(aq) + H2S(aq) ¡ Cr2O3(s) + SO42- (a) Element oxidized Oxidizing agent O HCrO4- (c) H2(g) + Mg2+(aq) ¡ H+(aq) + Mg(s) (d) Mg(s) + Ag+(aq) ¡ Mg2+(aq) + Ag(s) 15 The concentration of a solution of potassium permanganate, KMnO4, can be determined by titration with a known amount of oxalic acid, H2C2O4, according to the following equation: H2C2O4(aq) + KMnO4(aq) + H2SO4(aq) ¡ - (b) S HCrO4 (c) Cr H2S (d) Cr HCrO4- 14 The most strongly reducing elements are listed at the top of the partial activity series table provided Use the activity series to predict which reaction will occur (LO 4.20) K(s) ¡ K+(aq) + eMg(s) ¡ Mg2+(aq) + 2eH2(g) ¡ H+(aq) + 2eAg(s) ¡ Ag+(aq) + e- 10 CO2(g) + MnSO4(aq) + K2SO4(aq) + H2O(l) What is the concentration of a KMnO4 solution if 22.35 mL reacts with 0.5170 g of oxalic acid? (LO 4.22) (a) 0.6423 M (b) 0.1028 M (c) 0.4161 M (d) 0.2569 M ­Answers: a, d, c, b, d, d, a, c, b, 10 a, 11 b, 12 c, 13 b, 14 d, 15 b (a) Mg(s) + K+(aq) ¡ Mg2+(aq) + K(s) (b) Ag(s) + H+(aq) ¡ Ag+(aq) + H2(g) Mastering Chemistry    provides end-of-chapter exercises, feedback-enriched tutorial problems, animations, and interactive activities to encourage problem-solving practice and deeper understanding of key concepts and topics RAN  Randomized in Mastering Chemistry CONCEPTUAL PROBLEMS Problems 4.1–4.36 appear within the chapter 4.37 Box (a) represents 1.0 mL of a solution of particles at a RAN given concentration Which of the boxes (b)–(d) represents 1.0 mL of the solution that results after (a) has been diluted by doubling the volume of its solvent? 4.38 Assume that an aqueous solution of a cation, represented as a red sphere, is allowed to mix with a solution of an anion, represented as a yellow sphere Three possible outcomes are represented by boxes (1)–(3): (a) + (1) (b) (c) (2) (3) (d) Which outcome corresponds to each of the following reactions? (a) Na+(aq) + CO32-(aq) S (b) Ba2+(aq) + CrO42-(aq) S (c) Ag+(aq) + SO32-(aq) S Conceptual Problems     153 4.39 Assume that an aqueous solution of a cation, represented as a blue sphere, is allowed to mix with a solution of an anion, represented as a red sphere, and that the following result is obtained: OCl-1aq2 + 2I -1aq2 + 2H+1aq2 S Cl-1aq2 + I21aq2 + H2O1l2 + Which combinations of cation and anion, chosen from the following lists, are compatible with the observed results? Explain Cations: Na+, Ca2+, Ag+, Ni2+ Anions: Cl-, CO32-, CrO42-, NO3 4.40 The following pictures represent aqueous solutions of three acids HA (A = X, Y, or Z), with surrounding water molecules omitted for clarity Which of the three is the strongest acid, and which is the weakest? = HA 4.42 The concentration of an aqueous solution of NaOCl (sodium RAN hypochlorite; the active ingredient in household bleach) can be determined by a redox titration with iodide ion in acidic solution: = H3O+ HX Assume that the blue spheres in the buret represent I - ions, the red spheres in the flask represent OCl- ions, the concentration of the I - ions in the buret is 0.120 M, and the volumes in the buret and the flask are identical What is the concentration of NaOCl in the flask? What percentage of the I - solution in the buret must be added to the flask to react with all the OCl- ions? = A- HY + HZ 4.41 Assume that an aqueous solution of OH-, represented as a blue sphere, is allowed to mix with a solution of an acid HnA, represented as a red sphere Three possible outcomes are depicted by boxes (1)–(3), where the green spheres represent An-, the anion of the acid: + 4.43 Assume that the electrical conductivity of a solution depends on the total concentration of dissolved ions and that you measure the conductivity of three different solutions while carrying out titration procedures: (a) Begin with 1.00 L of 0.100 M KCl, and titrate by adding 0.100 M AgNO3 (b) Begin with 1.00 L of 0.100 M HF, and titrate by adding 0.100 M KOH (c) Begin with 1.00 L of 0.100 M BaCl2, and titrate by adding 0.100 M Na2SO4 Which of the following graphs corresponds to which titration? (3) Conductivity (2) Liters of titrant Liters of titrant (3) Which outcome corresponds to each of the following reactions? (a) HF + OH- ¡ H2O + F(b) H2SO3 + OH- ¡ H2O + SO32(c) H3PO4 + OH- S H2O + PO43- Conductivity (1) (2) Conductivity (1) Liters of titrant 154     chapter    Reactions in Aqueous Solution 4.44 Based on the positions in the periodic table, which of the following reactions would you expect to occur? (a) Red+ + Green S Red + Green+ (b) Blue + Green+ S Blue+ + Green (c) Red + Blue+ S Red+ + Blue 4.45 The following two redox reactions occur between aqueous cations and solid metals Will a solution of green cations react with solid blue metal? Explain (a) (b) SECTION PROBLEMS Molarity (Section 4.1) 4.46 How many moles of solute are present in each of the followRAN ing solutions? (a) 35.0 mL of 1.200 M HNO3 (b) 175 mL of 0.67 M glucose (C6H12O6) 4.47 How many grams of solute would you use to prepare each RAN of the following solutions? (a) 250.0 mL of 0.600 M ethyl alcohol (C2H6O) (b) 167 mL of 0.200 M boric acid (H3BO3) 4.48 How many milliliters of a 0.45 M BaCl2 solution contain RAN 15.0 g of BaCl2? 4.49 How many milliliters of a 0.350 M KOH solution contain RAN 0.0171 mol of KOH? 4.50 The sterile saline solution used to rinse contact lenses can RAN be made by dissolving 400 mg of NaCl in sterile water and diluting to 100 mL What is the molarity of the solution? 4.51 The concentration of glucose (C6H12O6) in normal blood is approximately 90 mg per 100 mL What is the molarity of the glucose? 4.52 Copper reacts with dilute nitric acid according to the followRAN ing equation: Cu(s) + HNO3(aq) ¡ Cu(NO3)2(aq) + NO(g) + H2O(l) If a copper penny weighing 3.045 g is dissolved in a small amount of nitric acid and the resultant solution is diluted to 50.0 mL with water, what is the molarity of the Cu(NO3)2? 4.53 The estimated concentration of gold in the oceans is RAN 1.0 * 10 - 11 g/mL (a) Express the concentration in mol/L (b) Assuming that the volume of the oceans is 1.3 * 1021 L, estimate the amount of dissolved gold in grams in the oceans 4.54 How many grams of solute would you use to prepare the RAN following solutions? (a) 500.0 mL of 1.25 M NaOH (b) 1.50 L of 0.250 M glucose (C6H12O6) 4.55 How would you prepare 500 mL of a 0.330 M solution of RAN CaCl2 from solid CaCl2? Specify the glassware that should be used 4.56 How would you prepare 250 mL of a 0.100 M solution of fluoride ions from solid CaF2? Specify the glassware that should be used Dilutions (Section 4.2) 4.57 Pennies minted after 1982 are mostly zinc (97.5%) with RAN a copper cover If a post-1982 penny is dissolved in a small amount of nitric acid, the copper coating reacts as in Problem 4.52, and the exposed zinc reacts according to the following equation: Zn(s) + HNO3(aq) ¡ Zn(NO3)2(aq) + H2(g) 4.58 RAN 4.59 RAN 4.60 4.61 RAN For a penny that weighs 2.482 g, what is the molarity of the Zn(NO3)2 if the resultant solution is diluted to 250.0 mL with water? A bottle of 12.0 M hydrochloric acid has only 35.7 mL left in it What will the HCl concentration be if the solution is diluted to 250.0 mL? What is the volume of the solution that would result by diluting 70.00 mL of 0.0913 M NaOH to a concentration of 0.0150 M? How would you prepare 250 mL of a 0.100 M solution of chloride ions from a 3.00 M stock solution of CaCl2? Specify the glassware that should be used How would you prepare 250 mL of 0.150 M solution of CaCl2 from a 3.00 M stock solution? Specify the glassware that should be used Section Problems     155 Electrolytes (Section 4.3) 4.62 The following aqueous solutions were tested with a light RAN bulb conductivity apparatus, as shown in Figure 4.3 What result—dark, dim, or bright—do you expect from each? (a) 0.10 M potassium chloride (b) 0.10 M methanol (c) 0.10 M acetic acid 4.63 The following aqueous solutions were tested with a light bulb conductivity apparatus, as shown in Figure 4.3 What result—dark, dim, or bright—do you expect from each? (a) 0.10 M hydrofluoric acid (b) 0.10 M sodium chloride (c) 0.10 M glucose (C6H12O6) 4.64 Individual solutions of Ba(OH)2 and H2SO4 both conduct electricity, but the conductivity disappears when equal molar amounts of the solutions are mixed Explain 4.65 A solution of HCl in water conducts electricity, but a solution of HCl in chloroform, CHCl3, does not What does this observation tell you about how HCl exists in water and how it exists in chloroform? 4.66 Classify each of the following substances as a strong electrolyte, weak electrolyte, or nonelectrolyte (a) HBr (b) HF (c) NaClO4 (d) (NH4)2CO3 (e) NH3 (f) Ethyl alcohol 4.67 Is it possible for a molecular substance to be a strong electrolyte? Explain 4.68 What is the total molar concentration of ions in each of the RAN following solutions, assuming complete dissociation? (a) A 0.750 M solution of K2CO3 (b) A 0.355 M solution of AlCl3 4.69 What is the total molar concentration of ions in each of the RAN following solutions? (a) A 1.250 M solution of CH3OH (b) A 0.225 M solution of HClO4 4.70 Ringer’s solution, used in the treatment of burns and wounds, RAN is prepared by dissolving 4.30 g of NaCl, 0.150 g of KCl, and 0.165 g of CaCl2 in water and diluting to a volume of 500.0 mL What is the molarity of each of the component ions in the solution? 4.71 What is the molarity of each ion in a solution prepared by disRAN solving 0.550 g of Na2SO4, 1.188 g of Na3PO4, and 0.223 g of Li2SO4 in water and diluting to a volume of 100.00 mL? Net Ionic Equations and Aqueous Reactions (Sections 4.4–4.5) 4.72 Classify each of the following reactions as a precipitation, acid–base neutralization, or oxidation–reduction (a) Hg(NO3)2(aq) + NaI(aq) S NaNO3(aq) + HgI2(s) heat (b) HgO(s) ¡ Hg(l) + O2(g) (c) H3PO4(aq) + KOH(aq) S K3PO4(aq) + H2O(l) 4.73 Classify each of the following reactions as a precipitation, acid–base neutralization, or oxidation–reduction (a) S8(s) + 8O2(g) S 8SO2(g) (b) NiCl2(aq) + Na2S(aq) S NiS(s) + NaCl(aq) (c) CH3CO2H(aq) Ba(OH)2(aq) S              (CH3CO2)2Ba(aq) + H2O(l) 4.74 Write net ionic equations for the reactions listed in RAN Problem 4.72 4.75 Write net ionic equations for the reactions listed in RAN Problem 4.73 Precipitation Reactions and Solubility Guidelines (Section 4.6) 4.76 Which of the following substances are likely to be soluble in RAN water? (a) PbSO4 (b) Ba(NO3)2 (c) SnCO3 (d) (NH4)3PO4 4.77 Which of the following substances are likely to be soluble in RAN water? (a) ZnS (b) AU2(CO3)3 (c) PbCl2 (d) Na2S 4.78 Predict whether a precipitation reaction will occur when RAN aqueous solutions of the following substances are mixed For those that form a precipitate, write the net ionic reaction (a) NaOH + HClO4 (b) FeCl2 + KOH (c) (NH4)2SO4 + NiCl2 (d) CH3CO2Na + HCl 4.79 Predict whether a precipitation reaction will occur when RAN aqueous solutions of the following substances are mixed For those that form a precipitate, write the net ionic reaction (a) MnCl2 + Na2S (b) HNO3 + CuSO4 (c) Hg(NO3)2 + Na3PO4 (d) Ba(NO3)2 + KOH 4.80 Which of the following solutions will not form a precipitate RAN when added to 0.10 M BaCl2? (a) 0.10 M LiNO3 (b) 0.10 M K2SO4 (c) 0.10 M AgNO3 4.81 Which of the following solutions will not form a precipitate RAN when added to 0.10 M NaOH? (a) 0.10 M MgBr2 (b) 0.10 M NH4Br (c) 0.10 M FeCl2 4.82 How would you prepare the following substances by a preRAN cipitation reaction? (a) PbSO4 (b) Mg3(PO4)2 (c) ZnCrO4 4.83 How would you prepare the following substances by a precipitation reaction? (a) Al(OH)3 (b) FeS (c) CoCO3 4.84 What are the mass and the identity of the precipitate that RAN forms when 30.0 mL of 0.150 M HCl reacts with 25.0 mL of 0.200 M AgNO3? 4.85 What are the mass and the identity of the precipitate that RAN forms when 55.0 mL of 0.100 M BaCl2 reacts with 40.0 mL of 0.150 M Na2CO3? 4.86 Assume that you have an aqueous mixture of NaNO3 and AgNO3 How could you use a precipitation reaction to separate the two metal ions? 4.87 Assume that you have an aqueous mixture of BaCl2 and CuCl2 How could you use a precipitation reaction to separate the two metal ions? 4.88 Assume that you have an aqueous solution of an unknown salt Treatment of the solution with dilute NaOH, Na2SO4, 156     chapter 4.89 4.90 4.91 4.92 RAN 4.93 RAN    Reactions in Aqueous Solution and KCl produces no precipitate Which of the following cations might the solution contain? (a) Ag+ (b) Cs + 2+ (c) Ba (d) NH4+ Assume that you have an aqueous solution of an unknown salt Treatment of the solution with dilute BaCl2, AgNO3, and Cu(NO3)2 produces no precipitate Which of the following anions might the solution contain? (a) Cl(b) NO3(c) OH (d) SO42How could you use a precipitation reaction to separate each of the following pairs of cations? Write the formula for each reactant you would add, and write a balanced net ionic equation for each reaction (a) K+ and Hg22+ (b) Pb2+ and Ni2+ 2+ + (c) Ca and NH4 (d) Fe2+ and Ba2+ How could you use a precipitation reaction to separate each of the following pairs of anions? Write the formula for each reactant you would add, and write a balanced net ionic equation for each reaction (a) Cl- and NO3(b) S2- and SO4222(c) SO4 and CO3 (d) OH- and ClO4The following three solutions are mixed: 100.0 mL of 0.100 M Na2SO4, 50.0 mL of 0.300 M ZnCl2, and 100.0 mL of 0.200 M Ba(CN)2 (a) What ionic compounds will precipitate out of solution? (b) What is the molarity of each ion remaining in the solution assuming complete precipitation of all insoluble compounds? A 250.0 g sample of a white solid is known to be a mixture of KNO3, BaCl2, and NaCl When 100.0 g of this mixture is dissolved in water and allowed to react with excess H2SO4, 67.3 g of a white precipitate is collected When the remaining 150.0 g of the mixture is dissolved in water and allowed to react with excess AgNO3, 197.6 g of a second precipitate is collected (a) What are the formulas of the two precipitates? (b) What is the mass of each substance in the original 250 g mixture? Acids, Bases, and Neutralization Reactions (Section 4.7) 4.94 Assume that you are given a solution of an unknown acid or base How can you tell whether the unknown substance is acidic or basic? 4.95 Why we use a double arrow ( ∆ ) to show the dissociation of a weak acid or weak base in aqueous solution? 4.96 Write balanced ionic equations for the following reactions (a) Aqueous perchloric acid is neutralized by aqueous calcium hydroxide (b) Aqueous sodium hydroxide is neutralized by aqueous acetic acid 4.97 Write balanced ionic equations for the following reactions RAN (a) Aqueous hydrobromic acid is neutralized by aqueous calcium hydroxide (b) Aqueous barium hydroxide is neutralized by aqueous nitric acid 4.98 Write balanced net ionic equations for the following reactions (a) LiOH(aq) + HI(aq) ¡ ? (b) HBr(aq) + Ca(OH)2(aq) S ? 4.99 Write balanced net ionic equations for the following reactions Note that HClO3 is a strong acid (a) Fe(OH)3(s) + H2SO4(aq) S ? (b) HClO3(aq) + NaOH(aq) ¡ ? Solution Stoichiometry and Titration (Sections 4.8–4.9) 4.100 A flask containing 450 mL of 0.500 M HBr was accidentally RAN knocked to the floor How many grams of K2CO3 would you need to put on the spill to neutralize the acid according to the following equation? HBr(aq) + K2CO3(aq) ¡ KBr(aq) + CO2(g) + H2O(l) 4.101 The odor of skunks is caused by chemical compounds called RAN thiols These compounds, of which butanethiol (C4H10S) is a representative example, can be deodorized by reaction with household bleach (NaOCl) according to the following equation: C4H10S + NaOCl(aq) ¡ C8H18S2 + NaCl + H2O(aq) Butanethiol How many grams of butanethiol can be deodorized by reaction with 5.00 mL of 0.0985 M NaOCl? 4.102 Potassium permanganate (KMnO4) reacts with oxalic acid RAN (H2C2O4) in aqueous sulfuric acid according to the following equation: KMnO4 + H2C2O4 + H2SO4 ¡ MnSO4 + 10 CO2 + H2O + K2SO4 How many milliliters of a 0.250 M KMnO4 solution are needed to react completely with 3.225 g of oxalic acid? 4.103 Oxalic acid, H2C2O4, is a toxic substance found in spinach leaves What is the molarity of a solution made by dissolving 12.0 g of oxalic acid in enough water to give 400.0 mL of solution? How many milliliters of 0.100 M KOH would you need to titrate 25.0 mL of the oxalic acid solution according to the following equation? H2C2O4(aq) + KOH(aq) ¡ K2C2O4(aq) + H2O(l) Oxalic acid 4.104 How many milliliters of 1.00 M KOH must be added to RAN neutralize the following solutions? (a) A mixture of 0.240 M LiOH (25.0 mL) and 0.200 M HBr (75.0 mL) (b) A mixture of 0.300 M HCl (45.0 mL) and 0.250 M NaOH (10.0 mL) Section Problems     157 4.105 How many milliliters of 2.00 M HCl must be added to neuRAN tralize the following solutions? (a) A mixture of 0.160 M HNO3 (100.0 mL) and 0.100 M KOH (400.0 mL) (b) A mixture of 0.120 M NaOH (350.0 mL) and 0.190 M HBr (150.0 mL) 4.106 If the following solutions are mixed, is the resulting solution RAN acidic, basic, or neutral? (a) 50.0 mL of 0.100 M HBr and 30.0 mL of 0.200 M KOH (b) 100.0 mL of 0.0750 M HCl and 75.0 mL of 0.100 M Ba(OH)2 4.107 If the following solutions are mixed, is the resulting solution RAN acidic, basic, or neutral? (a) 65.0 mL of 0.0500 M HClO4 and 40.0 mL of 0.0750 M NaOH (b) 125.0 mL of 0.100 M HNO3 and 90.0 mL of 0.0750 M Ca(OH)2 Oxidation Numbers (Section 4.10) 4.108 Assign oxidation numbers to each element in the following compounds (a) NO2 (b) SO3 (c) COCl2 (d) CH2Cl2 (e) KClO3 (f) HNO3 4.109 Assign oxidation numbers to each element in the following compounds (a) VOCl3 (b) CuSO4 (c) CH2O (d) Mn2O7 (e) OsO4 (f) H2PtCl6 4.110 Assign oxidation numbers to each element in the following ions (a) ClO3(b) SO32(c) C2O42(d) NO2 (e) BrO (f) AsO43 4.111 Assign oxidation numbers to each element in the following ions (a) Cr(OH)4(b) S2O32(c) NO3(d) MnO42(e) HPO42(f) V2O74 4.112 Nitrogen can have several different oxidation numbers rangRAN ing in value from - to +5 (a) Write the formula and give the name of the nitrogen oxide compound in which nitrogen has an oxidation number of +1, +2, + 4, and +5 (b) Based on oxidation numbers, which nitrogen oxide from part (a) cannot react with molecular oxygen? 4.113 Phosphorus can have several different oxidation numbers ranging in value from - to + (a) When phosphorus burns in air or oxygen, it yields either tetraphosphorus hexoxide or tetraphosphorus decoxide Write the formula and give the oxidation number for each compound (b) Based on oxidation numbers, which phosphorus oxide compound from part (a) was formed by combustion with a limited supply of oxygen? Redox Reactions (Section 4.11) 4.114 Where in the periodic table are the best reducing agents found? The best oxidizing agents? 4.115 Where in the periodic table are the most easily reduced elements found? The most easily oxidized? 4.116 In each of the following instances, tell whether the substance gains electrons or loses electrons in a redox reaction (a) An oxidizing agent (b) A reducing agent (c) A substance undergoing oxidation (d) A substance undergoing reduction 4.117 Tell for each of the following substances whether the oxidation number increases or decreases in a redox reaction (a) An oxidizing agent (b) A reducing agent (c) A substance undergoing oxidation (d) A substance undergoing reduction 4.118 Which element is oxidized and which is reduced in each of RAN the following reactions? (a) Ca(s) + Sn2+(aq) S Ca2+(aq) + Sn(s) (b) ICl(s) + H2O(l) S HCl(aq) + HOI(aq) 4.119 Which element is oxidized and which is reduced in each of the following reactions? (a) Si(s) + Cl2(g) S SiCl4(l) (b) Cl2(g) + NaBr(aq) S Br2(aq) + NaCl(aq) Activity Series (Section 4.12) 4.120 Use the activity series of metals (Table 4.5) to predict the RAN outcome of each of the following reactions If no reaction occurs, write NR (a) Na+(aq) + Zn(s) S ? (b) HCl(aq) + Pt(s) S ? (c) Ag+(aq) + Au(s) S ? (d) Au3+(aq) + Ag(s) S ? 4.121 Neither strontium (Sr) nor antimony (Sb) is shown in the activity series of Table 4.5 Based on their positions in the periodic table, which would you expect to be the better reducing agent? Will the following reaction occur? Explain Sb3+(aq) + Sr(s) ¡ Sb(s) + Sr2+(aq) 4.122 (a) Use the following reactions to arrange the elements A, B, C, and D in order of their decreasing ability as reducing agents: A + B+ ¡ A+ + B C + + D ¡ no reaction B + D+ ¡ B+ + D B + C + ¡ B+ + C (b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)? (1) A+ + C ¡ A + C + (2) A+ + D ¡ A + D+ 4.123 (a) Use the following reactions to arrange the elements A, B, C, and D in order of their decreasing ability as reducing agents: A + B2+ ¡ A+ + B B + D2+ ¡ B2+ + D A+ + C ¡ no reaction 2C + B2+ ¡ C + + B (b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)? (1) A+ + D ¡ A + D2+ (2) D2+ + C ¡ D + C + Redox Titrations (Section 4.13) 4.124 Iodine, I2, reacts with aqueous thiosulfate ion in neutral soluRAN tion according to the balanced equation I2(aq) + S2O32-(aq) ¡ S4O62-(aq) + I -(aq) 158     chapter    Reactions in Aqueous Solution How many grams of I2 are present in a solution if 35.20 mL of 0.150 M Na2S2O3 solution is needed to titrate the I2 solution? 4.125 How many milliliters of 0.250 M Na2S2O3 solution is RAN needed for complete reaction with 2.486 g of I2 according to the equation in Problem 4.124? 4.126 Dichromate ion, Cr2O72-, reacts with aqueous iron(II) ion in RAN acidic solution according to the balanced equation Cr2O7 2-(aq) + Fe2+(aq) + 14 H+(aq) ¡ Cr3+(aq) + Fe3+(aq) + H2O(l) What is the concentration of Fe2+ if 46.99 mL of 0.2004 M K2Cr2O7 is needed to titrate 50.00 mL of the Fe2+ solution? 4.127 A volume of 18.72 mL of 0.1500 M K2Cr2O7 solution was RAN required to titrate a sample of FeSO4 according to the equation in Problem 4.126 What is the mass of the sample? 4.128 What is the molar concentration of As(III) in a solution if RAN 22.35 mL of 0.100 M KBrO3 is needed for complete reaction with 50.00 mL of the As(III) solution? The balanced equation is: H3AsO3(aq) + BrO3-(aq) ¡ Br -(aq) + H3AsO4(aq) 4.129 Standardized solutions of KBrO3 are frequently used in RAN redox titrations The necessary solution can be made by dissolving KBrO3 in water and then titrating it with an As(III) solution What is the molar concentration of a KBrO3 solution if 28.55 mL of the solution is needed to titrate 1.550  g of As2O3? See Problem 4.128 for the balanced equation (As2O3 dissolves in aqueous acid solution to yield H3AsO3: As2O3 + H2O S H3AsO3.) 4.130 The metal content of iron in ores can be determined by a RAN redox procedure in which the sample is first oxidized with Br2 to convert all the iron to Fe3+ and then titrated with Sn2+ to reduce the Fe3+ to Fe2+ The balanced equation is: Fe3+(aq) + Sn2+(aq) ¡ Fe2+(aq) + Sn4+(aq) What is the mass percent Fe in a 0.1875 g sample of ore if 13.28 mL of a 0.1015 M Sn2+ solution is needed to titrate the Fe3+? 4.131 The concentration of the Sn2+ solution used in Problem 4.130 RAN can be found by letting it react with a known amount of Fe2+ What is the molar concentration of an Sn2+ solution if 23.84 mL is required for complete reaction with 1.4855 g of Fe 2O3? 4.132 Alcohol levels in blood can be determined by a redox reaction RAN with potassium dichromate according to the balanced equation C2H5OH(aq) + Cr2O72-(aq) + 16 H+ (aq) ¡ CO2(g) + Cr3+(aq) + 11 H2O(l) What is the blood alcohol level in mass percent if 8.76 mL of 0.049 88 M K2Cr2O7 is required for complete reaction with a 10.002 g sample of blood? 4.133 Calcium levels in blood can be determined by adding oxaRAN late ion to precipitate calcium oxalate, CaC2O4, followed by dissolving the precipitate in aqueous acid and titrating the resulting oxalic acid (H2C2O4) with KMnO4: H2C2O4(aq) + MnO4-(aq) + H+ (aq) ¡ 10 CO2(g) + Mn2+(aq) + H2O(l) How many milligrams of Ca2+ are present in 10.0 mL of blood if 21.08 mL of 0.000 988 M KMnO4 solution is needed for the titration? MULTICONCEPT PROBLEMS 4.134 Assume that you have 1.00 g of a mixture of benzoic acid RAN (Mol wt = 122) and gallic acid (Mol wt = 170)), both of which contain one acidic hydrogen that reacts with NaOH On titrating the mixture with 0.500 M NaOH, 14.7 mL of base is needed to completely react with both acids What mass in grams of each acid is present in the original mixture? 4.135 A compound with the formula XOCl2 reacts with water, yielding HCl and another acid H2XO3, which has two acidic hydrogens that react with NaOH When 0.350 g of XOCl2 was added to 50.0 mL of water and the resultant solution was titrated, 96.1 mL of 0.1225 M NaOH was required to react with all the acid (a) Write a balanced equation for the reaction of XOCl2 with H2O (b) What are the atomic mass and identity of element X? 4.136 A procedure for determining the amount of iron in a sample RAN is to convert the iron to Fe2+ and then titrate it with a solution of Ce(NH4)2(NO3)6: 2+ 4+ 3+ 3+ Fe (aq) + Ce (aq) ¡ Fe (aq) + Ce (aq) What is the mass percent of iron in a sample if 1.2284 g of the sample requires 54.91 mL of 0.1018 M Ce(NH4)2(NO3)6 for complete reaction? 4.137 Some metals occur naturally in their elemental state while others occur as compounds in ores Gold, for instance, is found as the free metal; mercury is obtained by heating mercury(II) sulfide ore in oxygen; and zinc is obtained by heating zinc(II) oxide ore with coke (carbon) Judging from their positions in the activity series, which of the metals silver, platinum, and chromium would probably be obtained by (a) finding it in its elemental state? (b) heating its sulfide with oxygen? (c) heating its oxide with coke? 4.138 A sample weighing 14.98 g and containing a small amount RAN of copper was treated to give a solution containing aqueous Cu2+ ions Sodium iodide was then added to yield solid copper(I) iodide plus I3- ion, and the I3- was titrated with thiosulfate, S2O32- The titration required 10.49 mL of 0.100 M Na2S2O3 for complete reaction What is the mass percent copper in the sample? The balanced equations are Cu2+(aq) + I -(aq) ¡ CuI(s) + I3-(aq) I3-(aq) + S2O32-(aq) ¡ I -(aq) + S4O62-(aq) 4.139 The solubility of an ionic compound can be described quanRAN titatively by a value called the solubility product constant, Ksp For the general solubility process AaBb ∆ a An+ + b Bm-, Ksp = [An+]a [Bm-]b The brackets refer to concentrations in moles per liter (a) Write the expression for the solubility product constant of Ag2CrO4 (b) If Ksp = 1.1 * 10-12 for Ag2CrO4, what are the molar concentrations of Ag+ and CrO42- in solution? Multiconcept Problems     159 4.140 Write the expression for the solubility product constant of RAN MgF2 (see Problem 4.139) If [Mg2+ ] = 2.6 * 10 -4 mol/L in a solution, what is the value of Ksp? 4.141 A 100.0 mL solution containing aqueous HCl and HBr was RAN titrated with 0.1235 M NaOH The volume of base required to neutralize the acid was 47.14 mL Aqueous AgNO3 was then added to precipitate the Cl- and Br - ions as AgCl and AgBr The mass of the silver halides obtained was 0.9974 g What are the molarities of the HCl and HBr in the original solution? 4.142 A mixture of CuO and Cu2O with a mass of 10.50 g is reduced RAN to give 8.66 g of pure Cu metal What are the amounts in grams of CuO and Cu2O in the original mixture? 4.143 A sample of metal (M) reacted with both steam and aqueous RAN HCl to release H2 but did not react with water at room temperature When 1.000 g of the metal was burned in oxygen, it formed 1.890 g of a metal oxide, M2O3 What is the identity of the metal? 4.144 An unknown metal (M) was found not to react with either RAN water or steam, but its reactivity with aqueous acid was not investigated When a 1.000 g sample of the metal was burned in oxygen and the resulting metal oxide converted to a metal sulfide, 1.504 g of sulfide was obtained What is the identity of the metal? 4.145 A mixture of acetic acid (CH3CO2H; monoprotic) and oxalic RAN acid (H2C2O4; diprotic) requires 27.15 mL of 0.100 M NaOH to neutralize it When an identical amount of the mixture is titrated, 15.05 mL of 0.0247 M KMnO4 is needed for complete reaction What is the mass percent of each acid in the mixture? (Acetic acid does not react with MnO4- The equation for the reaction of oxalic acid with MnO4- was given in Problem 4.133.) 4.146 Iron content in ores can be determined by a redox procedure RAN in which the sample is first reduced with Sn2+ , as in Problem 4.130, and then titrated with KMnO4 to oxidize the Fe2+ to Fe3+ The balanced equation is MnO4-(aq) + Fe2 + (aq) + H + (aq) ¡ Mn2+(aq) + Fe3+(aq) + H2O(l) What is the mass percent Fe in a 2.368 g sample if 48.39 mL of a 0.1116 M KMnO4 solution is needed to titrate the Fe3 + ? 4.147 A mixture of FeCl2 and NaCl is dissolved in water, and addiRAN tion of aqueous silver nitrate then yields 7.0149 g of a precipitate When an identical amount of the mixture is titrated with MnO4-, 14.28 mL of 0.198 M KMnO4 is needed for complete reaction What are the mass percents of the two compounds in the mixture? (Na+ and Cl- not react with MnO4- The equation for the reaction of Fe2+ with MnO4was given in Problem 4.146.) 4.148 Salicylic acid, used in the manufacture of aspirin, contains only the elements C, H, and O and has only one acidic hydrogen that reacts with NaOH When 1.00 g of salicylic acid undergoes complete combustion, 2.23 g CO2 and 0.39 g H2O are obtained When 1.00 g of salicylic acid is titrated with 0.100 M NaOH, 72.4 mL of base is needed for complete reaction What are the empirical and molecular formulas of salicylic acid? 4.149 Compound X contains only the elements C, H, O, and S A 5.00 g sample undergoes complete combustion to give 4.83 g of CO2, 1.48 g of H2O, and a certain amount of SO2 that is further oxidized to SO3 and dissolved in water to form sulfuric acid, H2SO4 On titration of the H2SO4, 109.8 mL of 1.00 M NaOH is needed for complete reaction (Both H atoms in sulfuric acid are acidic and react with NaOH.) (a) What is the empirical formula of X? (b) When 5.00 g of X is titrated with NaOH, it is found that X has two acidic hydrogens that react with NaOH and that 54.9 mL of 1.00 M NaOH is required to completely neutralize the sample What is the molecular formula of X? 4.150 A 1.268 g sample of a metal carbonate (MCO3) was treated RAN with 100.00 mL of 0.1083 M sulfuric acid (H2SO4), yielding CO2 gas and an aqueous solution of the metal sulfate (MSO4) The solution was boiled to remove all the dissolved CO2 and was then titrated with 0.1241 M NaOH A 71.02 mL volume of NaOH was required to neutralize the excess H2SO4 (a) What is the identity of the metal M? (b) How many liters of CO2 gas were produced if the density of CO2 is 1.799 g/L? 4.151 Element M is prepared industrially by a two-step procedure RAN according to the following (unbalanced) equations: (1)  M2O3(s) + C(s) + Cl2(g) ¡ MCl3(l) + CO(g) (2)  MCl3(l) + H2(g) ¡ M(s) + HCl(g) Assume that 0.855 g of M2O3 is submitted to the reaction sequence When the HCl produced in step (2) is dissolved in water and titrated with 0.511 M NaOH, 144.2 mL of the NaOH solution is required to neutralize the HCl (a) Balance both equations (b) What is the atomic mass of element M, and what is its identity? (c) What mass of M in grams is produced in the reaction? 4.152 Assume that you dissolve 10.0 g of a mixture of NaOH RAN and Ba(OH)2 in 250.0 mL of water and titrate with 1.50 M hydrochloric acid The titration is complete after 108.9 mL of the acid has been added What is the mass in grams of each substance in the mixture? 4.153 Four solutions are prepared and mixed in the following order: (a) Start with 100.0 mL of 0.100 M BaCl2 (b) Add 50.0 mL of 0.100 M AgNO3 (c) Add 50.0 mL of 0.100 M H2SO4 (d) Add 250.0 mL of 0.100 M NH3 Write an equation for any reaction that occurs after each step, and calculate the concentrations of Ba2+, Cl -, NO3-, NH3, and NH4+ in the final solution, assuming that all reactions go to completion 4.154 To 100.0 mL of a solution that contains 0.120 M Cr(NO3)2 RAN and 0.500 M HNO3 is added to 20.0 mL of 0.250 M K2Cr2O7 The dichromate and chromium(II) ions react to give chromium(III) ions (a) Write a balanced net ionic equation for the reaction (b) Calculate the concentrations of all ions in the solution after reaction Check your concentrations to make sure that the solution is electrically neutral 4.155 Sodium nitrite, NaNO2, is frequently added to processed RAN meats as a preservative The amount of nitrite ion in a sample can be determined by acidifying to form nitrous acid (HNO2), letting the nitrous acid react with an excess of iodide ion, and then titrating the I3- ion that results with thiosulfate solution 160     chapter    Reactions in Aqueous Solution in the presence of a starch indicator The unbalanced equations are (1) HNO2 + I - ¡ NO + I3- (in acidic solution) (2) I3- + S2O32- ¡ I - + S4O62(a) Balance the two redox equations (b) When a nitrite-containing sample with a mass of 2.935 g was analyzed, 18.77 mL of 0.1500 M Na2S2O3 solution was needed for the reaction What is the mass percent of NO2- ion in the sample? 4.156 Brass is an approximately 4:1 alloy of copper and zinc, along RAN with small amounts of tin, lead, and iron The mass percents of copper and zinc can be determined by a procedure that begins with dissolving the brass in hot nitric acid The resulting solution of Cu2+ and Zn2+ ions is then treated with aqueous ammonia to lower its acidity, followed by addition of sodium thiocyanate (NaSCN) and sulfurous acid (H2SO3) to precipitate copper(I) thiocyanate (CuSCN) The solid CuSCN is collected, dissolved in aqueous acid, and treated with potassium iodate (KIO3) to give iodine, which is then titrated with aqueous sodium thiosulfate (Na2S2O3) The filtrate remaining after CuSCN has been removed is neutralized by addition of aqueous ammonia, and a solution of diammonium hydrogen phosphate ((NH4)2HPO4) is added to yield a precipitate of zinc ammonium phosphate (ZnNH4PO4) Heating the precipitate to 900 °C converts it to zinc pyrophosphate (Zn2P2O7), which is weighed The equations are (1) Cu(s) + NO3-(aq) ¡ Cu2+(aq) + NO(g) (in acid) (2) Cu2+(aq) + SCN-(aq) + HSO3-(aq) ¡ CuSCN(s) + HSO4-(aq) (in acid) + (3) Cu (aq) + IO3 (aq) ¡ Cu2+(aq) + I2(aq) (in acid) (4) I2(aq) + S2O32-(aq) ¡ I -(aq) + S4O62-(aq) (in acid) (5) ZnNH4PO4(s) ¡ Zn2P2O7(s) + H2O(g) + NH3(g) (a) Balance all equations (b) When a brass sample with a mass of 0.544 g was subjected to the preceding analysis, 10.82 mL of 0.1220 M sodium thiosulfate was required for the reaction with iodine What is the mass percent copper in the brass? (c) The brass sample in part (b) yielded 0.246 g of Zn2P2O7 What is the mass percent zinc in the brass? 4.157 A certain metal sulfide, MSn (where n is a small integer), is RAN widely used as a high-temperature lubricant The substance is prepared by reaction of the metal pentachloride (MCl5) with sodium sulfide (Na2S) Heating the metal sulfide to 700 °C in air gives the metal trioxide (MO3) and sulfur dioxide (SO2), which reacts with Fe3+ ion under aqueous acidic conditions to give sulfate ion (SO42-) Addition of aqueous BaCl2 then forms a precipitate of BaSO4 The unbalanced equations are: (1) MCl5(s) + Na2S(s) ¡ MSn(s) + S(l) + NaCl(s) (2) MSn(s) + O2(g) ¡ MO3(s) + SO2(g) (3) SO2(g) + Fe3+(aq) ¡ Fe2+(aq) + SO42-(aq) (in acid) (4) SO42-(aq) + Ba2+(aq) ¡ BaSO4(s) Assume that you begin with 4.61 g of MCl5 and that reaction (1) proceeds in 91.3% yield After oxidation of the MSn product, oxidation of SO2, and precipitation of sulfate ion, 7.19 g of BaSO4(s) is obtained (a) How many moles of sulfur are present in the MSn sample? (b) Assuming several possible values for n (n = 1, 2, c ), what is the atomic weight of M in each case? (c) What is the likely identity of the metal M, and what is the formula of the metal sulfide MSn? (d) Balance all equations 4.158 On heating a 0.200 g sample of a certain semimetal M in air, the corresponding oxide M2O3 was obtained When the oxide was dissolved in aqueous acid and titrated with KMnO4, 10.7 mL of 0.100 M MnO4- was required for complete reaction The unbalanced equation is H3MO3(aq) + MnO4-(aq) ¡ H3MO4(aq) + Mn2+(aq) (in acid) (a) Balance the equation (b) How many moles of oxide were formed, and how many moles of semimetal were in the initial 0.200 g sample? (c) What is the identity of the semimetal M? ... Cataloging-in-Publication Data Names: Robinson, Jill K | McMurry, John | Fay, Robert C. , 1936Title: Chemistry / Jill K Robinson (Indiana University), John E McMurry (Cornell University), Robert C Fay (Cornell... 98 (251) Carbon C 12.0107 Cerium Ce 58 140.116 Cesium Cs 55 132.90545 Chlorine Cl 17 35.453 Chromium Cr 24 51.9961 Cobalt Co 27 58.933195 Copernicium Cn 112 (285) Copper Cu 29 63.546 Curium Cm 96 (247... thank all accuracy reviewers, text reviewers, and our colleagues at so many other institutions who read, criticized, and improved our work Jill K Robinson John McMurry Robert C Fay For Instructors