Preview Chemistry the molecular science, 5th Edition by Moore, John W.Stanitski, Conrad L (2015)

Preview Chemistry the molecular science, 5th Edition by Moore, John W.Stanitski, Conrad L (2015) Preview Chemistry the molecular science, 5th Edition by Moore, John W.Stanitski, Conrad L (2015) Preview Chemistry the molecular science, 5th Edition by Moore, John W.Stanitski, Conrad L (2015) Preview Chemistry the molecular science, 5th Edition by Moore, John W.Stanitski, Conrad L (2015) Preview Chemistry the molecular science, 5th Edition by Moore, John W.Stanitski, Conrad L (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 Group number, IUPAC system Group number, U.S system Period number H 20 19 Francium (223) Fr 87 Cesium 132.9055 Cs 55 Rubidium 85.4678 Rb 37 Potassium 39.0983 57 89 Radium (226) Actinium (227) Ac 88 Ra Lanthanum 138.9055 Barium 137.327 La 56 Ba Yttrium 88.9058 Strontium 87.62 H Li Be Na Mg K Ca Sc Rb Sr Y Cs Ba La Fr Ra Ac Ti Zr Hf Rf He F Ne Cl Ar Br Kr I Xe At Rn —— Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu AmCm Bk Cf Es Fm Md No Lr B C N O Al Si P S V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po Db Sg Bh Hs Mt Ds Rg Cn — Fl — Lv 7B (7) Thorium 232.0377 Th 90 Cerium 140.116 58 Ce Dubnium (268) 105 Db Tantalum 180.9479 73 Ta Niobium 92.9064 41 Nb Vanadium 50.9415 V 23 43 Tc Manganese 54.9380 25 Mn 8B (8) 92 91 61 Pm Hassium (277) 108 Hs Osmium 190.23 76 Os Ruthenium 101.07 44 Ru Iron 55.845 26 Fe Protactinium 231.0359 Pa Uranium 238.0289 U 8B (9) 8B (10) 1B (11) 2B (12) 47 111 Rg 110 Ds Gold 196.9666 79 Au Silver 107.8682 Platinum 195.084 78 Pt Palladium 106.42 Ag 46 Pd Copper 63.546 29 Cu Nickel 58.6934 28 Ni 112 Cn Mercury 200.59 80 Hg Cadmium 112.414 48 Cd Zinc 65.38 30 Zn Plutonium (244) 94 Pu Samarium 150.36 62 Sm 96 Americium (243) Curium (247) Cm 95 Am Gadolinium 157.25 64 Gd Europium 151.964 63 Eu Berkelium (247) 97 Bk Terbium 158.9254 65 Tb Meitnerium Darmstadtium Roentgenium Copernicium (281) (281) (285) (278) 109 Mt Iridium 192.217 77 Ir Rhodium 102.9055 45 Rh Cobalt 58.9332 27 Co Californium (251) 98 Cf Dysprosium 162.500 66 Dy — (286) Einsteinium (252) 99 Es Holmium 164.9303 67 Ho Flerovium (287) Fl 114 113 — Lead 207.2 82 Pb Tin 118.710 50 Sn Germanium 72.64 32 Ge Silicon 28.0855 Thallium 204.3833 81 Tl Indium 114.818 49 In Gallium 69.723 31 Ga Aluminum 26.9815 Fermium (257) 100 Fm Erbium 167.259 68 Er — (289) 115 — Bismuth 208.9804 83 Bi Antimony 121.760 51 Sb Arsenic 74.9216 33 As Phosphorus 30.9738 P 15 Nitrogen 14.0067 N 5A (15) Mendelevium (258) 101 Md Thulium 168.9342 69 Tm Livermorium (293) 116 Lv Polonium (209) 84 Po Tellurium 127.60 52 Te Selenium 78.97 34 Se Sulfur 32.065 S 16 Oxygen 15.9994 O 6A (16) Nobelium (259) 102 No Ytterbium 173.054 70 Yb — (293) 117 — Astatine (210) 85 At Iodine 126.9045 I 53 Bromine 79.904 35 Br Chlorine 35.453 17 Cl Fluorine 18.9984 F 7A (17) Elements for which the International Union of Pure and Applied Chemistry (IUPAC) has officially sanctioned the discovery and approved a name are indicated by their chemical symbols in this table Elements that have been reported in the literature but not yet officially sanctioned and named are indicated by atomic number Neptunium (237) 93 Np Praseodymium Neodymium Promethium 140.9077 144.242 (145) Nd 60 Bohrium (270) 107 Bh Rhenium 186.207 75 Re Pr 59 Seaborgium (271) 106 Sg Tungsten 183.84 74 W Molybdenum Technetium 95.95 (98) 42 Mo Chromium 51.9961 24 Cr This icon appears throughout the book to help locate elements of interest in the periodic table The halogen group is shown here Actinides Lanthanides Rutherfordium (267) Rf 104 Hafnium 178.49 72 Hf Zirconium 91.224 Zr 40 Y 39 38 Sr Titanium 47.867 22 Ti Scandium 44.9559 21 Sc Calcium 40.078 Ca Magnesium 24.3050 K 6B (6) 14 Si 13 Al 12 Mg Carbon 12.0107 C Boron 10.811 B 4A (14) Beryllium 9.0122 Be 5B (5) Nonmetals, noble gases Metalloids Transition metals Main group metals 4B (4) An element Atomic number Symbol Name Atomic weight 3A (13) 3B (3) Au Gold 196.9665 79 2A (2) Sodium 22.9898 Na 11 Lithium 6.941 Li 1A (1) Hydrogen 1.0079 Numbers in parentheses are mass numbers of radioactive isotopes 1 KEY PERIODIC TABLE OF THE ELEMENTS Lr Lawrencium (262) 103 Lutetium 174.9668 71 Lu — (294) 118 — Radon (222) 86 Rn Xenon 131.293 54 Xe Krypton 83.798 36 Kr Argon 39.948 18 Ar Neon 20.1797 10 Ne Helium 4.0026 He 8A (18) 7 Standard Atomic Weights  of the Elements 2009, IUPAC Name Symbol Actinium Aluminum Americium2 Antimony Argon Arsenic Astatine2 Barium Berkelium2 Beryllium Bismuth Bohrium2 Boron Bromine Cadmium Calcium Californium2 Carbon Cerium Cesium Chlorine Chromium Cobalt Copernicium2 Copper Curium2 Darmstadtium2 Dubnium2 Dysprosium Einsteinium2 Erbium Europium Fermium2 Flerovium2 Fluorine Francium2 Gadolinium Gallium Germanium Gold Hafnium Hassium2 Helium Holmium Hydrogen Indium Iodine Iridium Iron Krypton Lanthanum Lawrencium2 Lead Lithium Livermorium2 Lutetium Magnesium Manganese Meitnerium2 Ac Al Am Sb Ar As At Ba Bk Be Bi Bh B Br Cd Ca Cf C Ce Cs Cl Cr Co Cn Cu Cm Ds Db Dy Es Er Eu Fm Fl F Fr Gd Ga Ge Au Hf Hs He Ho H In I Ir Fe Kr La Lr Pb Li Lv Lu Mg Mn Mt Atomic Number  89  13  95  51  18  33  85  56  97   4  83 107   5  35  48  20  98   6  58  55  17  24  27 112  29  96 110 105  66  99  68  63 100 114   9  87  64  31  32  79  72 108   2  67   1  49  53  77  26  36  57 103  82   3 116  71  12  25 109 Based on Relative Atomic Mass of 12C = 12, where in its nuclear and electronic ground state.1 Atomic Weight (227) 26.981 5385(7) (243) 121.760(1) 39.948(1) 74.921 595(6) (210) 137.327(7) (247) 9.012 1831(5) 208.980 40(1) (270) 10.811(7) 79.904(1) 112.414(4) 40.078(4) (251) 12.0107(8) 140.116(1) 132.905 451 96(6) 35.453(2) 51.9961(6) 58.933 194(4) (285) 63.546(3) (247) (281) (268) 162.500(1) (252) 167.259(3) 151.964(1) (257) (287) 18.998 403 163(6) (223) 157.25(3) 69.723(1) 72.64(1) 196.966 569(5) 178.49(2) (277) 4.002 602(2) 164.930 33(2) 1.00794(7) 114.818(3) 126.904 47(3) 192.217(3) 55.845(2) 83.798(2) 138.905 47(7) (262) 207.2(1) [6.941(2)]† (293) 174.9668(1) 24.3050(6) 54.938 044(3) (278) Name Mendelevium Mercury Molybdenum Neodymium Neon Neptunium2 Nickel Niobium Nitrogen Nobelium2 Osmium Oxygen Palladium Phosphorus Platinum Plutonium2 Polonium2 Potassium Praseodymium Promethium2 Protactinium2 Radium2 Radon2 Rhenium Rhodium Roentgenium2 Rubidium Ruthenium Rutherfordium2 Samarium Scandium Seaborgium2 Selenium Silicon Silver Sodium Strontium Sulfur Tantalum Technetium2 Tellurium Terbium Thallium Thorium2 Thulium Tin Titanium Tungsten Uranium2 Vanadium Xenon Ytterbium Yttrium Zinc Zirconium —2,3 —2,3 —2,3 —2,3 12 C is a neutral atom Symbol Atomic Number Md Hg Mo Nd Ne Np Ni Nb N No Os O Pd P Pt Pu Po K Pr Pm Pa Ra Rn Re Rh Rg Rb Ru Rf Sm Sc Sg Se Si Ag Na Sr S Ta Tc Te Tb Tl Th Tm Sn Ti W U V Xe Yb Y Zn Zr 101  80  42  60  10  93  28  41   7 102  76   8  46  15  78  94  84  19  59  61  91  88  86  75  45 111  37  44 104  62  21 106  34  14  47  11  38  16  73  43  52  65  81  90  69  50  22  74  92  23  54  70  39  30  40 113 115 117 118 Atomic Weight (258) 200.59(2) 95.95(1) 144.242(3) 20.1797(6) (237) 58.6934(4) 92.906 37(2) 14.0067(2) (259) 190.23(3) 15.9994(3) 106.42(1) 30.973 761 998(5) 195.084(9) (244) (209) 39.0983(1) 140.907 66(2) (145) 231.035 88(2) (226) (222) 186.207(1) 102.905 50(2) (281) 85.4678(3) 101.07(2) (267) 150.36(2) 44.955 908(5) (271) 78.971(8) 28.0855(3) 107.8682(2)   22.989 769 28(2) 87.62(1) 32.065(5) 180.947 88(2) (98) 127.60(3) 158.925 35(2) 204.3833(2) 232.0377(4) 168.934 22(2) 118.710(7) 47.867(1) 183.84(1) 238.028 91(3) 50.9415(1) 131.293(6) 173.054(5) 88.905 84(2) 65.38(2) 91.224(2) (286) (289) (293) (294) The atomic weights of many elements vary depending on the origin and treatment of the sample This is particularly true for Li; commercially available lithium-containing materials have Li atomic weights in the range of 6.939 and 6.996 Uncertainties are given in parentheses following the last significant figure to which they are attributed Elements with no stable nuclide; the value given in parentheses is the atomic mass number of the isotope of longest known half-life However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and the atomic weight is tabulated for these Not yet named 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 F IF T H E D I T ION Chemistry The Molecular Science John W Moore Conrad L Stanitski University of Wisconsin–Madison Franklin and Marshall College 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 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: The Molecular Science, Fifth Edition John W Moore, Conrad L Stanitski Product Director: Mary Finch Product Manager: Maureen Rosener Managing Developer: Peter McGahey Associate Content Developer: Brendan Killion Product Assistant: Karolina Kiwak © 2015, 2011 Cengage Learning WCN: 02-200-203 ALL RIGHTS RESERVED No part of this work covered by the copyright herein may be reproduced, transmitted, stored, or used in any form or by any means, graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the publisher Media Developer: Rebecca Berardy Schwartz Marketing Director: Nicole Hamm Content Project Manager: Teresa L Trego Art Director: Maria Epes Manufacturing Planner: Judy Inouye Rights Acquisitions Specialist: Dean Dauphinais For product information and technology assistance, contact us at Cengage Learning Customer & Sales Support, 1-800-354-9706 For 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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 17 16 15 14 13 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 To All Students of Chemistry We intend that this book will help you to discover that chemistry is relevant to your lives and careers, full of beautiful ideas and phenomena, and of great benefit to society May your study of this fascinating subject be exciting, successful, and fun! We thank our wives—Betty (  JWM) and Barbara (CLS)—for their patience, support, understanding, and love It does not harm to the mystery to know a little more about it —Richard Feynman 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 John W Moore received an A.B magna cum laude from Franklin and Marshall College and a Ph.D from Northwestern University He held a National Science Foundation (NSF) postdoctoral fellowship at the University of Copenhagen and taught at Indiana University and Eastern Michigan University before joining the faculty of the University of Wisconsin–Madison in 1989 At the University of Wisconsin, Dr Moore is W T Lippincott Professor of Chemistry and Director of the Institute for Chemical Education He was Editor of the Journal of Chemical Education from 1996 to 2009 Among his many awards are the American Chemical Society (ACS) George C Pimentel Award in Chemical Education, the James Flack Norris Award for Excellence in Teaching Chemistry, and the CMA CATALYST National Award for Excellence in Chemistry Teaching He is a Fellow of the ACS and of the American Association for the Advancement of Science (AAAS) He has won two major awards from the University of Wisconsin: the Wisconsin Power and Light Underkofler Award for Excellence in Teaching (1995) and the Benjamin Smith Reynolds Award for excellence in teaching chemistry to engineering students (2003) Dr Moore has received a series of major grants from the NSF to support development of online chemistry learning materials for the ChemEd DL and the National Science Distributed Learning (NSDL) initiative © Dr Donal R Neu © Dr Donal R Neu About the Authors Conrad L Stanitski is currently a Visiting Scholar at Franklin and Marshall College and is Distinguished Emeritus Professor of Chemistry at the University of Central Arkansas He received his B.S in Science Education from Bloomsburg State College, M.A in Chemical Education from the University of Northern Iowa, and Ph.D in Inorganic Chemistry from the University of Connecticut He has co-authored chemistry textbooks for science majors, allied health science students, nonscience majors, and high school chemistry students Among Dr Stanitski’s many awards are the American Chemical Society George C Pimentel Award in Chemical Education, the CMA CATALYST National Award for Excellence in Chemistry Teaching, the Gustav Ohaus–National Science Teachers Association Award for Creative Innovations in College Science Teaching, the Thomas R Branch Award for Teaching Excellence, the Samuel Nelson Gray Distinguished Professor Award from Randolph-Macon College, and the 2002 Western Connecticut American Chemical Society Section Visiting Scientist Award He was Chair of the American Chemical Society Division of Chemical Education (2001) and has been an elected Councilor for that division He is a Fellow of the American Association for the Advancement of Science (AAAS) An instrumental and vocal performer, he also enjoys jogging, tennis, rowing, and reading 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 1 The Nature of Chemistry 2 Chemical Compounds 3 Chemical Reactions 4 Energy and Chemical Reactions 5 Electron Configurations and the Periodic Table 6 Covalent Bonding 7 Molecular Structures 8 Properties of Gases 9 Liquids, Solids, and Materials 10 Fuels, Organic Chemicals, and Polymers 11 Chemical Kinetics: Rates of Reactions 12 Chemical Equilibrium 13 The Chemistry of Solutes and Solutions 14 Acids and Bases 15 Additional Aqueous Equilibria 16 Thermodynamics: Directionality of Chemical Reactions 17 Electrochemistry and Its Applications 18 Nuclear Chemistry 19 The Chemistry of the Main-Group Elements 20 Chemistry of Selected Transition Elements and Coordination Compounds 42 91 149 190 241 284 326 371 422 475 524 564 606 653 694 738 783 818 857 Appendices A–J  A.1 Appendix K: Answers to Problem-Solving Practice Problems   A.49 Appendix L: Answers to Exercises   A.66 Appendix M: Answers to Selected Questions for Review and Thought   A.88 Glossary  G.1 Index  I.1 v 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 2-12 Composition and Chemical Formulas 24.3050 g = 24.3050 g mol Mg 32.065 g Mass S = mol S × = 32.065 g mol S Mass Mg = mol Mg × Mass O = 11 mol O × 15.9994 g = 175.993 g mol O Mass H = 14 mol H × 1.0079 g = 14.111 g mol H Mass H 2O = mol H 2O × (22 × 1.0079 + 15.9994) g = 126.106 g mol H 2O 24.3050 g × 100% = 9.8604% 246.49 g 32.065 g Percent S = × 100% = 13.001% 246.49 g 175.993 g Percent O = × 100% = 71.400% 246.49 g 14.111 g × 100% = 5.7248% Percent H = 246.49 g 126.106 g Percent H 2O = × 100% = 51.161% 246.49 g Percent Mg =   Reasonable Result Check  In the formula of the hydrated salt, there are seven waters with a combined mass of × 18 = 126 g, and there are six other atoms with molar masses ranging between 16 and 32 that total to 120 g Thus, the hydrated salt should be about 50% water by weight, and it is There are 11 oxygen atoms in the formula, so oxygen should have the largest percent by weight, and it does The percentages sum to 99.986% which is within rounding error of 100% Problem-Solving Practice 2.18 Calculate the mass percent of each element in hydrated sodium sulfate, Na2SO4 j10H2O Exercise 2.21 Composition Express the composition of each compound first as the mass of each element in 1.000 mol of the compound and then as the mass percent of each element: (a) SF6        (b) C12H22O11        (c) Al2(SO4)3        (d) U(OTeF5)6 2-12a Empirical and Molecular Formulas Historically, chemical formulas were obtained by experimentally determining the masses of two or more elements that combined to form a compound Such data give the percent composition by mass of a compound and we can determine the formula of a compound from mass percent data This depends on the fact that the subscripts in a formula indicate how many moles of each element there are per mole of the compound Consider diborane, a compound consisting of boron and hydrogen that ignites explosively when exposed to air Experiments show that diborane is 78.13% B and 21.87% H Based on these percentages, a 100.0-g diborane sample contains 78.13 g B and 21.87 g H From this information we can calculate the amount of each element in the sample: Unless otherwise noted, all content on this page is © Cengage Learning 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 85 86 Chapter   |  CHEMICAL COMPOUNDS mol B = 7.227 mol B 10.811 g B mol H Amount H = 21.87 g H × = 21.70 mol H 1.0079 g H Amount B = 78.13 g B × To determine the formula from these data, we next apply the idea that the subscripts in a formula indicate the relative number of moles of each element For example, the formula H2O indicates the ratio mol H∶1 mol O Thus we find the amount of each element rela­ tive to the amount of the other element or elements—in this case, the ratio of amount of hydrogen to amount of boron There are about three times as many moles of H atoms as there are moles of B atoms To calculate the ratio exactly, we divide the larger amount by the smaller amount For diborane that ratio is Amount H 21.70 mol H 3.003 mol H = = Amount B 7.227 mol B 1.000 mol B Molecular formula molar mass = n, empirical formula mo olar mass where n is an integer If n = 1, the molecular formula and the empirical formula are the same When n  1, the subscripts in the molecular formula are all n times the subscripts in the empirical formula This ratio confirms that there are three moles of H atoms for every one mole of B atoms and that there are three hydrogen atoms for each boron atom This information gives the formula BH3 For a molecular compound such as diborane, the molecular formula must also accurately reflect the total number of atoms in a molecule of the compound The calculation we have done gives the simplest possible ratio of atoms in the molecule, and BH3 is the simplest formula for diborane A formula that reports the simplest possible whole-number ratio of atoms in the molecule is called an empirical formula Multiples of the simplest formula that maintain the ratio H∶1 B are possible, such as B2H6, B3H9, and so on One way to determine which of these formulas is the actual molecular formula involves experimentally determining the molar mass of the compound The experimental molar mass can be compared with the molar mass predicted by the empirical formula If the two molar masses are the same, the empirical and molecular formulas are the same However, if the experimentally determined molar mass is some multiple of the empirical formula value, the molecular formula is that multiple of the empirical formula In the case of diborane, experiments indicate that the molar mass is 27.67 g/mol The empirical formula, BH3, predicts a molar mass of 13.83 g/mol, so the molecular formula must be a multiple of the empirical formula That multiple is 27.67/13.83 = 2.00 Thus, the molecular formula of diborane is B(2×1)H(2×3), or B2H6 Problem-Solving Example 2.19 Determining Formulas An oxide of phosphorus contains 56.34% P and 43.66% O Its experimentally determined molar mass is 219.90 g/mol Determine the formula of this compound Result   Empirical formula: P2O3; molecular formula: P4O6 Analyze  The compound contains only nonmetals, so it is probably molecular; hence a molecular formula must be determined You know the mass of each element per 100 g compound, so you can calculate the relative amounts of each element and determine an empirical formula The molar mass tells what multiple of the empirical formula is needed for the molecular formula Plan  Calculate the amount of each element Use mole ratios to determine the empirical for- mula Compare the experimental molar mass with the molar mass from the empirical formula Execute   A 100-g sample of the compound contains 56.34 g P and 43.66 g O; thus mol P = 1.819 mol P 30.9738 g P mol O Amount O = 43.66 g O × = 2.729 mol O 15.9994 g O Amount P = 56.34 g P × Unless otherwise noted, all content on this page is © Cengage Learning 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 2-12 Composition and Chemical Formulas The ratio of the larger amount to the smaller amount is Amount O 2.729 mol O 1.500 mol O = = Amount P 1.819 mol P 1.000 mol P The ratio is 1.5 O atoms per 1.0 P atom, but we cannot have half an atom If both numbers in the ratio are doubled, we have 3.0 O atoms per 2.0 P atoms, which gives the empirical formula P2O3 The corresponding molar mass is (2 × 30.9738 + × 15.9994) g/mol = 109.95 g/mol, about half the experimental molar mass: Experimental molar mass 219.90 g/mol = = 2.000 Molar mass from formula 109.95 g/mol Thus the subscripts in the empirical formula P2O3 need to be doubled to obtain the molecular formula, which is P4O6   Reasonable Result Check  The molar mass of P is nearly twice the molar mass of O If the subscripts in the formula were equal, then we should have twice the mass of P as mass of O If the subscript of O was twice that of P, then the masses should be equal The actual percentages are 56% P and 44% O, so the ratio of O to P must be between 2∶1 and 1∶1 Our result of 1.5∶1 is reasonable Problem-Solving Practice 2.19 Hydrazine is composed of 87.42% nitrogen and 12.58% hydrogen by mass Its experimentally determined molar mass is 32.05 g/mol Determine the empirical and molecular formulas of hydrazine It is not necessary to know percent composition to determine a chemical formula All that is needed is a way to determine the masses of the elements that combine to form a compound If you know the mass of each element in a sample of a compound, then you can calculate the amount of each element and from the ratios of amounts you can determine the formula Problem-Solving Example 2.20 Formula from Mass Data A 63.47-g sample of an ionic compound contains 17.17 g sodium and 10.46 g nitrogen; the rest is oxygen The compound’s molar mass is 84.9947 g/mol Determine its formula Result  NaNO3 Analyze  The compound is ionic, so it does not consist of molecules and does not have a molecular formula; determine the empirical formula The mass of oxygen in the sample is not given, but it can be calculated by subtracting the other masses from the mass of the sample Because all masses refer to the same sample, the masses can be used to calculate the amounts of each element in the sample The empirical formula can be determined from the relative amounts of the elements compound The molar mass is not needed to determine the formula, but it can be used to check the result Plan  Calculate the mass of oxygen by subtraction Then calculate the amount of each ele- ment and determine the mole ratios Execute   m(O) = m(sample) − m(Na) − m(N) = 63.47 g − 17.17 g − 10.46 g = 35.84 g mol Na = 0.7469 mol Na 22.9898 g Na mol N Amount N = 10.46 g N × = 0.7468 mol N 14.0067 g N mol O Amount O = 35.84 g O × = 2.240 mol O 15.9994 g O Amount Na = 17.17 g Na × Unless otherwise noted, all content on this page is © Cengage Learning 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 87 88 Chapter   |  CHEMICAL COMPOUNDS When there are three or more amounts, divide each of the others by the smallest to obtain mole ratios Amount Na 0.7469 mol Na 1.000 mol Na = = Amount N 0.7468 mol N 1.000 mol N 2.999 mol O Amount O 2.240 mol O = = 0.7468 mol N 1.000 mol N Amount N Na and N are in a 1∶1 mole ratio, but the ratio O∶N is 2.999 There is experimental error in the mass data, so it is reasonable to round 2.999 to The formula is NaNO3 HO C O C   Reasonable Result Check  The molar mass is given, so calculate the molar mass from OH O the formula NaNO3 C H H C H C C O H H vitamin C Molar mass = (22.9898 + 14.0067 + × 15.9994) g/mol = 84.9947 g/mol OH The result is reasonable Problem-Solving Practice 2.20 Vitamin C (ascorbic acid) contains 40.9% C, 4.58% H, and 54.5% O and has an experimentally determined molar mass of 176.13 g/mol Determine its empirical and molecular formulas Exercise 2.22 Formula of a Hydrate A sample of a hydrate was heated to drive off water After the water was gone the sample was found to contain 11.013 g Ca, 8.811 g S, and 17.59 g O The water was collected and weighed; its mass was 9.903 g Use this information to determine the formula of the hydrate Summary Problem Part I An isotope of an element contains 63 protons and 91 neutrons (a) Identify the element and give its symbol (b) Give the element’s atomic number (c) Give the mass number of the isotope (d) This element has two naturally occurring isotopes Given the information in the table, calculate the atomic weight of the element Isotope Mass Number Percent Abundance Isotopic Mass (u) 151 153 47.80 52.20 150.920 152.921 (e) In which region of the periodic table is the element found? Explain your answer (f) Is the element a metal, metalloid, or nonmetal? Explain your answer (g) This element, used in compact fluorescent light bulbs and computer screens, has an atomic radius of 180 pm Calculate how long the chain of atoms would be if all the atoms in a 1.25-mg sample of this element were put into a row Unless otherwise noted, all content on this page is © Cengage Learning 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 Having Studied This Chapter Part II Consider these three nitrogen-containing compounds: ammonium dichromate, ammonium nitrate, and trinitrotoluene A molecule of trinitrotoluene contains seven carbon atoms, five hydrogen atoms, three nitrogen atoms, and six oxygen atoms All three compounds are solids at room temperature and all three decompose at high temperatures (a) Write the correct formula for each compound (b) Determine which compound has the highest mass percent nitrogen (c) Which compound has the lowest melting point? Explain your choice (d) Which compounds, if any, conduct electric current at room temperature? At a much higher temperature? Explain (e) If they could be melted without decomposing, which compound (if any) would conduct electricity? Part III The mineral fluorapatite has the formula Ca5(PO4)3F Hypo, a substance used when photographs were developed chemically, has the formula Na2S2O3j5H2O Weddellite has the formula CaC2O4j2H2O and is involved in formation of kidney stones (a) Identify the ions and their charges in these three compounds (b) Calculate the molar mass of each compound Part IV Dioxathion, a pesticide, contains carbon, hydrogen, oxygen, phosphorus, and sulfur The compound has this mass percent composition: 31.57% C; 5.74% H; 21.03% O The mass percent sulfur is 2.07 times that of phosphorus Dioxathion has a molar mass of 456.64 g/mol (a) Determine the empirical formula of dioxathion (b) Determine the molecular formula of dioxathion (c) A 57.50 mg dose of this pesticide is administered in a laboratory test Calculate the amount of dioxathion in this dose (d) Calculate the number of molecules of dioxathion in the dose Having Studied This Chapter you should be able to: • Describe radioactivity, electrons, protons, and neutrons, and the general structure of the atom (Sections 2-1, 2-2).  End-of-chapter Questions 7, 9, 11 • Define isotope and determine the atomic number, mass number, and number of neutrons for a specified isotope (Section 2-3).  Questions 18, 20 • Find the atomic number and atomic weight for any element and explain how these two terms differ (Section 2-3) Questions 24, 119 • Understand the kinds of information that can be obtained from scanning tunneling microscopy and mass spectrometry (Sections 2-2, 2-3).  Questions 14, 16 • Calculate the average atomic mass or atomic weight of an element from isotopic abundances and isotopic masses (Section 2-3).  Questions 22, 26, 28 • Know the charges on monoatomic ions of metals and nonmetals (Section 2-4; Figure 2.7).  Questions 30, 32, 34 • Know the names and formulas of polyatomic ions (Section 2-4; Table 2.2).  Unless otherwise noted, all content on this page is © Cengage Learning 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 89 90 Chapter   |  CHEMICAL COMPOUNDS • Be able to recognize ionic compounds and describe their properties (Sections 2-4, 2-6).  Questions 38, 48, 117 • Given their names, write the formulas of ionic compounds; given formulas, write names (Section 2-5).  Questions 36, 40, 42, 46, 127 • Interpret the meaning of molecular formulas, condensed formulas, and structural formulas (Section 2-7).  Questions 52, 54, 56 • Be able to recognize molecular compounds, describe their properties, and compare them with the properties of ionic compounds (Section 2-7).  Questions 50, 113 • Name binary molecular compounds, including straight-chain alkanes (Sections 2-8, 2-9).  Questions 58, 60 • Define the term “isomer”; write structural formulas for and identify straight- and branched-chain alkane constitutional isomers (Section 2-9).  Question 64, 126 • Define the unit “mole” and explain its importance as a means of counting nanoscale particles (Section 2-10).  Questions 68, 123 • Given a chemical formula, calculate molar mass; use the molar mass to relate mass and amount of substance (Section 2-11).  Questions 72, 76, 82 • Given the amount of substance, use the Avogadro constant to calculate the number of particles (atoms, molecules, ions) (Section 2-11).  Questions 74, 78, 80 • Based on its formula, describe the nanoscale makeup of a hydrated ionic compound and calculate its molar mass (Section 2-11).  Question 89 • Given a chemical formula, calculate mass percent composition (Section 2-12).  Question 87 • Use composition based on mass and molar mass to determine the empirical and molecular formulas of a compound (Section 2-12).  Questions 91, 96, 98 Key Terms alkane (Section 2-9) formula unit (2-6b) molecular weight (2-11a) amount of substance (2-10) formula weight (2-11b) monoatomic ion (2-4a) atomic force microscope (2-2b) hydrocarbon (2-9) neutron (2-2b) atomic number (Z) (2-2c) inorganic compounds (2-7) nucleus (2-2a) atomic structure (2-1) ions (2-1c) organic compounds (2-7) atomic weight (2-3a) ionic bonding (2-6a) oxoanions (2-5b) average atomic mass (2-3a) ionic compound (2-4) percent abundance (2-3a) Avogadro constant (NA) (2-10) ionic hydrate (2-11c) percent composition by mass (2-12) Avogadro’s number (2-10) isomers (2-9a) polyatomic ion (2-4b; Table 2.2) binary molecular compound (2-8) isotopes (2-3) proton (2-1c) chemical bond (2-7b) mass number (A) (2-2c) radioactivity (2-1a) condensed formula (2-7b) mass spectrometer (2-3) scanning tunneling microscope (2-2b) constitutional isomers (2-9a) mass spectrum (2-3) structural formula (2-7b) Coulomb’s law (2-6a) molar mass (2-11) structural isomers (2-9a) crystal lattice (2-6b) mole (mol) (2-10) unified atomic mass unit (u) (2-3) electron (2-1b) molecular compound (2-7) water of hydration (2-11c) empirical formula (2-12a) molecular formula (2-7b) Unless otherwise noted, all content on this page is © Cengage Learning 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 Questions for Review and Thought 90a Questions for Review and Thought Red-numbered questions have short answers at the back of this book in Appendix M and fully worked solutions in the Student ­Solutions Manual Review Questions These questions test vocabulary and simple concepts Identify the fundamental unit of electrical charge The positively charged particle in an atom is called the proton (a) Calculate how much heavier a proton is than an electron (b) What is the difference in the charge on a proton and an electron? In any given neutral atom, how many protons are there compared with the number of electrons? Atoms of elements can have varying numbers of neutrons in their nuclei (a) What are species called that have varying numbers of neutrons for the same element? (b) How the mass numbers vary for these species? (c) What are two common elements that exemplify this property? Define these terms: (a) unified atomic mass unit; (b) mass number; (c) molar mass; (d) isotope A dictionary defines the word “compound” as a “combination of two or more parts.” What are the “parts” of a chemical compound? Identify three pure (or nearly pure) compounds you have encountered today What is the difference between a compound and a mixture? Topical Questions These questions are keyed to the major topics in the chapter Usually a question that is answered at the back of the book is paired with a similar one that is not Atomic Structure: Subatomic Particles (Section 2-1) Complete the table below Name Electric Charge (C) 1.6022 × 10 Mass (g) −19 Deflected by Electric Field? 1.6726 × 10−24 alpha particle −1.6022 × 10−19 Electric Charge (C) If the nucleus of an atom were the size of a golf ball (4-cm diameter), what would be the diameter of the atom? 10 If the nucleus of an atom were the size of Earth, would the moon be within the atom? Would the sun be within the atom? (Use the Internet to find information about the distances from Earth to the moon and sun.) 11 Match these by placing the correct notation in the appropriate blank 67 67 67 72 34 Se    33As    35 Br    36 Kr a Contains 33 neutrons b Contains greatest number of neutrons c Contains equal number of protons and neutrons d Contains the same number of neutrons as there are protons in As-67 12 Match these by placing the correct notation in the appropriate blank 112 115 112 115 50 Sn    50 Sn    51 Sb    49 In a Contains 65 neutrons b Contains fewest number of neutrons c Contains greatest number of neutrons d Contains the same number of neutrons as there are protons in Sm-142 Tools of Chemistry (Sections 2-2 and 2-3) 13 Both scanning tunneling microscopy and mass spectrometry use electrons to help measure different properties of atoms and molecules Describe the role that electrons play in each technique 14 What nanoscale species are moving through a mass spectrometer during its operation? 15 What is plotted on the x-axis and on the y-axis in a mass spectrum? What information does a mass spectrum convey? 16 Bromine has two isotopes, bromine-79 (50.69% abundance) and bromine-81 (49.31% abundance) Draw a graph of the mass spectrum obtained when a sample of Br2 gas is run through a mass spectrometer 17 Chlorine consists of two isotopes, chlorine-35 (75.77% abundance) and chlorine-37 (24.23% abundance) Draw a graph of the mass spectrum obtained from a sample of Cl2 gas Isotopes and Average Atomic Mass (Section 2-3) Complete the table below Name The Nuclear Atom (Section 2-2) Mass (g) 1.6726 × 10−24 beta ray Red-numbered questions are answered in Appendix M Deflected by Electric Field? no 18 Uranium-235 and uranium-238 differ in terms of the number of subatomic particles For which subatomic particle is the number different and by how much? 19 Strontium-90 is a product formed when atomic bombs exploded How strontium-90 and strontium-88 differ in terms of the number of subatomic particles? 20 How many electrons, protons, and neutrons are present in an atom of cobalt-60? Unless otherwise noted, all content on this page is © Cengage Learning 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 90b Chapter   |  CHEMICAL COMPOUNDS 21 The artificial radioactive element technetium is used in many medical studies Give the number of electrons, protons, and neutrons in an atom of technetium-99 22 The atomic weight of bromine is 79.904 The natural abundance of 81Br, atomic weight 80.916289 u, is 49.31% What is the atomic weight of the only other natural isotope of bromine? 23 The atomic weight of boron is 10.811 The natural abundance of 10B is 19.91% Determine the atomic weight of the only other natural isotope of boron 24 Give the complete symbol AZ X for each of these atoms: (a) sodium with 12 neutrons, (b) argon with 21 neutrons, and (c) gallium with 38 neutrons 25 Give the complete symbol AZ X for each of these atoms: (a) nitrogen with neutrons, (b) zinc with 34 neutrons, and (c) xenon with 75 neutrons 26 Verify that the average atomic mass of lithium is 6.941, given this information: Li, exact mass = 6.015121 u percent abundance = 7.500% Li, exact mass = 7.016003 u percent abundance = 92.50% Mg, exact mass = 23.985042 u percent abundance = 78.99% 25 Mg, exact mass = 24.985837 u percent abundance = 10.00% 26 Mg, exact mass = 25.982593 u percent abundance = 11.01% 24 28 Gallium has two naturally occurring isotopes, 69Ga and 71 Ga, with masses of 68.9257 u and 70.9249 u, respectively Calculate the abundances of these isotopes of gallium 29 Argon has three naturally occurring isotopes: 0.3336% 36 Ar, 0.063% 38Ar, and 99.60% 40Ar Estimate the average atomic mass of argon If the masses of the isotopes are 35.968 u, 37.963 u, and 39.962 u, respectively, calculate the average atomic mass of natural argon Ions and Ionic Compounds (Section 2-4) 30 For each of these metals, write the chemical symbol for the corresponding monoatomic ion (with charge) (b) Strontium (d) Zinc 31 For each of these nonmetals, write the chemical symbol for the corresponding monoatomic ion (with charge) (a) Nitrogen (c) Chlorine (b) Sulfur (d) Iodine 32 Predict the charges for monoatomic ions of these elements (a) Magnesium (c) Iron (b) Phosphorus (d) Selenium 33 Predict the charges for monoatomic ions of these elements (a) Gallium (c) Silver (a) AlCl (c) Ga2O3 (b) NaF2 (d) MgS (a) Ca2O (c) Fe2O5 (b) SrCl2 (d) K2O (a) CF4 (c) Co(NO3)3 (e) KCN (b) SrBr2 (d) SiO2 (f ) SCl2 37 Which of these are the correct formulas of compounds? For those that are not, give the correct formula 38 Predict which compounds are ionic Explain your answers 39 Predict which compounds are ionic Explain your answers 27 Verify that the average atomic mass of magnesium is 24.3050, given this information: (a) Lithium (c) Aluminum 34 Cobalt is a transition metal and thus can form ions with at least two different charges Write the formulas for the compounds formed between cobalt ions and the oxide ion 35 Although not a transition element, lead can form two cations: Pb2+ and Pb4+ Write the formulas for the compounds of these ions with the chloride ion 36 Which of these are the correct formulas of compounds? For those that are not, give the correct formula (b) Fluorine (d) Nitrogen Red-numbered questions are answered in Appendix M (a) NaH (c) NH3 (e) HI (b) HCl (d) CH4 Naming Ions and Ionic Compounds (Section 2-5) 40 Determine the chemical formulas for barium sulfate, magnesium nitrate, and sodium acetate Each compound contains a monoatomic cation and a polyatomic anion What are the names and electrical charges of these ions? 41 Write the chemical formula for calcium nitrate, barium chloride, and ammonium phosphate What are the names and charges of all the ions in these three compounds? 42 Write the chemical formulas for these compounds (a) Nickel(II) nitrate (c) Lithium hypochlorite (e) Calcium sulfite (b) Sodium bicarbonate (d) Magnesium chlorate 43 Write the chemical formulas for these compounds (a) Iron(III) nitrate (c) Sodium phosphate (e) Sodium sulfate (b) Potassium carbonate (d) Calcium chlorite 44 Give the correct formula for each of these ionic compounds (a) Ammonium carbonate (c) Copper(II) bromide (b) Calcium iodide (d) Aluminum phosphate 45 Give the correct formula for each of these ionic compounds (a) Calcium hydrogen carbonate (b) Potassium permanganate (c) Magnesium perchlorate (d) Ammonium monohydrogen phosphate 46 Correctly name each of these ionic compounds (a) K2S (c) (NH4)3PO4 (e) Co2(SO4)3 (b) NiSO4 (d) Al(OH)3 (a) KH2PO4 (c) CrCl3 (e) Fe2(SO4)3 (b) CuSO4 (d) Ca(CH3COO)2 47 Correctly name each of these ionic compounds Unless otherwise noted, all content on this page is © Cengage Learning 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 Questions for Review and Thought 90c Ionic Compounds: Bonding and Properties (Section 2-6) Naming Binary Molecular Compounds (Section 2-8) 48 Solid magnesium oxide melts at 2800 °C This property, combined with the fact that magnesium oxide is not an electrical conductor, makes it an ideal heat insulator for electric wires in cooking ovens and toasters In contrast, solid NaCl melts at the relatively low temperature of 801 °C What is the formula of magnesium oxide? Suggest a reason that it has a melting temperature so much higher than that of NaCl 49 Assume you have an unlabeled bottle containing a white, crystalline powder The powder melts at 310 °C You are told that it could be NH3, NO2, or NaNO3 What you think it is and why? 58 Give the correct name for each compound Molecular Compounds (Section 2-7) 50 Identify each compound as ionic or molecular based on its formula or properties (a) Rb2O (b) C6H12 (c) Liquid at room temperature (d) Conducts electricity when molten 51 Identify each compound as ionic or molecular based on its formula or properties (a) Can be cleaved with a sharp wedge (b) Melts at −22.3 °C (c) MgBr2 (d) C5H10O2N 52 Given these condensed formulas, write the structural and molecular formulas (a) CH3OH (c) CH3CH2SCH2CH3 (b) CH3CH2NH2 (d) CH3CH2SH (a) CH3CH2NHCH2CH3 (c) CH3CHClCH3 (b) CH3NH2 (d) CH2OHCHOHCH2OH 53 Write molecular and structural formulas for these compounds 54 Write the molecular formula for each substance (a) The hydrocarbon heptane, which has seven carbon atoms and 16 hydrogen atoms (b) Acrylonitrile (the basis of Orlon and Acrilan fibers), which has three carbon atoms, three hydrogen atoms, and one nitrogen atom 55 Write the molecular formula for each substance (a) Fenclorac, an anti-inflammatory drug, which has 14 carbon atoms, 16 hydrogen atoms, two chlorine atoms, and two oxygen atoms (b) Vitamin B-12, which has 63 carbon atoms, 88 hydrogen atoms, one cobalt atom, 14 nitrogen atoms, 14 oxygen atoms, and one phosphorus atom 56 Give the total number of atoms of each element in one formula unit of each of these compounds (a) CaC2O4 (c) (NH4)2SO4 (e) K4Fe(CN)6 (b) C6H5CHCH2 (d) Pt(NH3)2Cl2 (a) C6H5COOC2H5 (c) NH2CH2CH2COOH (e) C6H2CH3(NO2)3 (b) HOOCCH2CH2COOH (d) C10H9NH2Fe 57 Give the total number of atoms of each element in each of these molecules Red-numbered questions are answered in Appendix M (a) SO2 (c) P4S10 (b) CCl4 (d) SF4 (a) HBr (c) Cl2O7 (b) ClF3 (d) BI3 (a) Nitrogen triiodide (c) Dinitrogen tetraoxide (b) Carbon disulfide (d) Selenium hexafluoride 59 Give the correct name for each compound 60 Write the correct formula for each compound 61 Write the correct formula for each compound (a) Bromine trichloride (b) Xenon trioxide (c) Diphosphorus tetrafluoride (d) Oxygen difluoride Organic Molecular Compounds (Section 2-9) 62 In a noncyclic alkane other than methane, what is the maximum number of hydrogen atoms that can be bonded to one carbon atom? 63 In a noncyclic alkane, what is the maximum number of carbon atoms that can be bonded to one carbon atom? 64 Consider two molecules that are constitutional isomers (a) What is the same on the molecular level between these two molecules? (b) What is different on the molecular level between these two molecules? 65 Draw structural formulas for the five constitutional isomers of C6H14 66 The noncyclic hydrocarbon eicosane has 20 carbon atoms in each molecule How many hydrogen atoms are in each molecule? 67 A cyclic hydrocarbon has 16 hydrogen atoms in each molecule How many carbon atoms are there per mol­ ecule? What is the name of the compound? Amount of Substance: The Mole (Section 2-10) 68 If you divide Avogadro’s number of pennies among the nearly 300 million people in the United States, and if each person could count one penny each second every day of the year for eight hours per day, calculate how long it would take to count the pennies 69 Why you think it is more convenient to use some chemical counting unit when doing calculations (chemists have adopted the unit of the mole, but it could have been something different) rather than using individual molecules? Molar Mass (Section 2-11) 70 Calculate the mass of (a) 2.5 mol boron (c) 1.25 × 10−3 mol iron (b) 0.015 mol O2 (d) 653 mol helium 71 Calculate the mass of (a) 6.03 mol gold (c) 15.6 mol Ne (b) 0.045 mol uranium (d) 3.63 × 10−4 mol plutonium 72 Calculate the amount of substance for each sample: (a) 127.08 g Cu (c) 16.75 g Al (e) 5.0 mg americium (b) 20.0 g calcium (d) 0.012 g potassium Unless otherwise noted, all content on this page is © Cengage Learning 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 90d Chapter   |  CHEMICAL COMPOUNDS 73 Calculate the amount of substance for each sample: (a) 16.0 g Na (c) 1.54 g P (e) 0.983 g Xe (b) 0.0034 g platinum (d) 0.876 g arsenic 74 If you have a 35.67-g piece of chromium metal on your car, calculate how many chromium atoms you have 75 If you have a ring that contains 1.94 g gold, calculate how many gold atoms are in the ring 76 You have a pure sample of the antiseptic aminacrine, C13H10N2 (a) Calculate the mass in grams of 0.06500 mol aminacrine (b) Calculate the number of aminacrine molecules in a 0.2480-g sample (c) Calculate the number of nitrogen atoms in this 0.2480-g sample (d) Calculate the mass of N in 100 g aminacrine 77 You have a pure sample of apholate, C12H24N9P3, a highly effective commercial insecticide (a) Calculate the molar mass of apholate (b) Calculate the mass of N in 100 g apholate (c) A sample containing 250.0 mg apholate is sprayed on an agricultural field Calculate the mass of phosphorus in this sample of apholate; express your result in grams (d) Calculate the number of phosphorus atoms in this sample of apholate 78 You have a U S penny that weighs 2.458 g and contains 2.40% copper by mass (a) Calculate the number of pennies needed to contain 2.458 g Cu (b) Calculate the amount of copper in the penny (c) Calculate the number of copper atoms in the penny 79 You have a sterling silver fork that contains 92.5% silver and weighs 43.2 g (a) Calculate the mass of silver in the fork (b) Calculate the amount of silver in the fork (c) Calculate the number of silver atoms in the fork 80 Fill in this table for mol methanol, CH3OH CH3OH Carbon Hydrogen Oxygen Amount of   substance Number of   molecules   or atoms Molar mass 81 Fill in this table for mol glucose, C6H12O6 C6H12O6 Carbon Hydrogen Oxygen Amount of   substance Number of   molecules   or atoms Molar mass 82 Calculate the amount of substance in 1.00 g of each compound (a) CH3OH, methanol (b) Cl2CO, phosgene, a poisonous gas Red-numbered questions are answered in Appendix M (c) Ammonium nitrate (d) Magnesium sulfate heptahydrate (Epsom salt) (e) Silver acetate 83 Calculate the amount of substance in 0.250 g of each compound (a) C7H5NO3S, saccharin, an artificial sweetener (b) C13H20N2O2, procaine, a painkiller used by dentists (c) C20H14O4, phenolphthalein, a dye 84 Acetaminophen, an analgesic, has the molecular formula C8H9O2N (a) Calculate the molar mass of acetaminophen (b) Calculate the amount of acetaminophen in 5.32 g acetaminophen (c) Calculate the mass of acetaminophen in 0.166 mol acetaminophen 85 An Alka-Seltzer tablet contains 324 mg aspirin, C9H8O4; 1904 mg NaHCO3; and 1000 mg citric acid, C6H8O7 (The last two compounds react with each other to provide the “fizz,” bubbles of CO2, when the tablet is put into water.) (a) Calculate the amount of each substance in the tablet (b) If you take one tablet, calculate how many aspirin mol­ ecules you are consuming 86 Calculate how many water molecules are in one drop of water (One drop of water is 20 mL, and the density of water is 1.0 g/mL.) Composition and Chemical Formulas (Section 2-12) 87 Calculate the molar mass of each of these compounds and the mass percent of each element (a) PbS, lead(II) sulfide, galena (b) C2H6, ethane, a hydrocarbon fuel (c) CH3COOH, acetic acid, an important ingredient in vinegar (d) NH4NO3, ammonium nitrate, a fertilizer 88 Three oxygen-containing compounds of iron are FeCO3, Fe2O3, and Fe3O4 Calculate the percent iron by mass in each iron compound 89 The copper-containing compound Cu(NH3)4SO4 jH2O is a beautiful blue solid Calculate the molar mass of the compound and the mass percent of each element 90 The compound Co(NO3)2j6H2O is a red solid that absorbs water from the atmosphere Calculate its molar mass and the mass percent of each element Also calculate the mass percent water 91 Quinine (molar mass = 324.41 g/mol) is used as a cardiac depressant It has this percent composition by mass: 74.04% C; 7.46% H; 8.64% N; and 9.86% O Use these data to determine (a) the empirical formula and (b) the molecular formula of quinine 92 About a century ago, Paul Ehrlich discovered Salvarsan, the first arsenical antibiotic that cured a targeted disease, syphilis The compound was the six hundred and sixth compound he tried against the disease, but the first one found to be effective against it The compound has molar mass 549.102 g/mol and this mass percent composition: 39.37% C; 3.304% H; 7.653% N; 8.741% O; 40.93% As (a) Calculate the empirical formula of Salvarsan (b) Determine the molecular formula of this compound Unless otherwise noted, all content on this page is © Cengage Learning 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 Questions for Review and Thought 93 The mineral uraninite is a uranium oxide that is 84.80% uranium by mass Show calculations to determine the correct empirical formula of uraninite 94 Carbonic anhydrase, an important enzyme in mammalian respiration, is a large zinc-containing protein with a molar mass of 3.00 × 104 g/mol The zinc is 0.218% by mass of the protein Determine how many zinc atoms each carbonic anhydrase molecule contains 95 Nitrogen fixation in the root nodules of peas and other legumes occurs with a reaction involving a molybdenumcontaining enzyme named nitrogenase This enzyme contains two Mo atoms per molecule and is 0.0872% Mo by mass Calculate the molar mass of the enzyme 96 Disilane, Si2Hx, contains 90.28% silicon by mass Calculate the value of x in this compound 97 Chalky, white crystals in mineral collections are often labeled borax, which has the molecular formula Na2B4O7 j10H2O, when actually they are partially dehydrated samples with the molecular formula Na2B4O7 j5H2O, which is more stable under the storage conditions Real crystals of borax are colorless and transparent (a) Calculate the percent mass that the mineral has lost when it partially dehydrates (b) Is the percent boron by mass the same in both compounds? 98 A well-known reagent in analytical chemistry, dimethyl­ glyoxime, has the empirical formula C2H4NO If its molar mass is 116.1 g/mol, determine the molecular formula of the compound 99 The molecular formula of ascorbic acid (vitamin C) is C6H8O6 What is its empirical formula? 100 The alum used in cooking is potassium aluminum sulfate hydrate, KAl(SO4)2 jx H2O To find the value of x, you can heat a sample of the compound to drive off all the water and leave only KAl(SO4)2 Assume that you heat 4.74 g of the hydrated compound and that it loses 2.16 g water Calculate the value of x General Questions These questions are not explicitly keyed to chapter topics; many require integration of several concepts 101 The density of a solution of sulfuric acid is 1.285 g/cm3, and it is 38.08% acid by mass Calculate the volume of the acid solution (in mL) you need to supply 125 g of sulfuric acid 102 The cancer drug cisplatin contains 65.0% platinum If you have 1.53 g of the compound, calculate how many grams of platinum the sample contains 103 Ethyl alcohol, C2H5OH, has a density of 0.789 g/mL at 25 °C Water weighs 1.00 kg/L at 25 °C Calculate the volume of ethanol that contains the same number of molecules as 1.00 L water 104 A common fertilizer used on lawns is designated as “16-4-8.” These numbers mean that the fertilizer contains 16% nitrogen-containing compounds, 4.0% phosphoruscontaining compounds, and 8.0% potassium-containing compounds You buy a 40.0-lb bag of this fertilizer and Red-numbered questions are answered in Appendix M 90e use all of it on your lawn Calculate the mass (g) of the phosphorus-containing compound you are putting on your lawn If the phosphorus-containing compound consists of 43.64% phosphorus (the rest is oxygen), calculate the mass (g) of phosphorus that are in 40.0 lb of this fertilizer 105 The fluoridation of city water supplies has been practiced in the United States for several decades because there is scientific evidence that fluoride prevents tooth decay, especially in young children Fluoridation is done by continuously adding sodium fluoride to water as it comes from a reservoir Assume you live in a medium-sized city of 150,000 people and that each person uses 175 gal water per day Calculate how many tons of sodium fluoride you must add to the water supply each year (365 days) to have the required fluoride concentration of part per million (that is, ton of fluoride per million tons of water) (Sodium fluoride is 45.0% fluoride, and U S gallon of water has a mass of 8.34 lb.) 106 Which one of these symbols conveys more information about the atom: 37Cl or 17Cl? Explain 107 Gems and precious stones are measured in carats, a mass unit equivalent to 200 mg If you have a 2.3-carat diamond in a ring, calculate the amount of carbon you have 108 The Statue of Liberty in New York harbor is made of 2.00 × 105 lb copper sheets bolted to an iron framework Calculate the mass and the amount of copper in the statue (1 lb = 454 g) 109 Two different halogens are present in a series known as interhalogen compounds Name these interhalogen compounds: (a) IBr; (b) BrF3; (c) I2Cl6; (d) ClF5; (e) IF7 110 A helium atom consists of two protons, two electrons, and two neutrons (a) Explain how these particles are arranged to make the atom (b) Calculate the mass of the atom in unified atomic mass units (Assume no change in mass of the particles when they are in the atom.) (c) Calculate the mass of the atom in grams (Assume no change in mass of the particles when they are in the atom.) (d) Calculate the mass (in grams) of a mole of these helium atoms Compare your result with the atomic weight given in the periodic table inside the front cover of the book 111 It’s final exam time and a student drinks a 1.93-oz bottle of 5-Hour Energy® to stay awake The drink contains, among other substances, 212 mg caffeine, C8H10N4O2 (a) Calculate the mass percent nitrogen in caffeine (b) Calculate the number of caffeine molecules that the student ingested (c) Calculate the number of carbon atoms in this mass of caffeine (d) An 8-oz cup of regular coffee contains approximately 100 mg caffeine Calculate how many times greater the caffeine concentration (mg/oz) is in the 5-Hour Energy® drink than in the regular coffee 112 (a) Calculate the mass of one molecule of nitrogen (b) Calculate the mass of one molecule of oxygen (c) Calculate the ratio of masses of these two molecules How does it compare with the ratio of the atomic weights of N and O? Unless otherwise noted, all content on this page is © Cengage Learning 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 90f Chapter   |  CHEMICAL COMPOUNDS 113 For each pair of elements, (i) through (vii), (a) Determine whether an ionic compound, a molecular compound, or no compound would form (b) Write an appropriate formula for each compound you expect to form and name the compound (i) Chlorine and bromine (ii) Lithium and tellurium (iii) Sodium and argon (iv) Magnesium and fluorine (v) Nitrogen and bromine (vi) Indium and sulfur (vii) Selenium and bromine 114 For each substance, (i) through (viii), (a) Write the correct formula (b) Decide whether the substance is ionic or molecular (i) Sodium hypochlorite (ii) Tetraphosphorus decaoxide (iii) Potassium permanganate (iv) Potassium dihydrogen phosphate (v) Chlorine trifluoride (vi) Boron tribromide (vii) Calcium acetate (viii) Sodium sulfite 115 Pepto-Bismol, which helps provide relief for an upset stomach, contains 300 mg bismuth subsalicylate, C7H5BiO4, per tablet (a) You take two tablets for your stomach distress Calculate the amount of the “active ingredient” you are taking (b) What mass of Bi did the two tablets contain? 118 Draw diagrams of each nanoscale situation given in parts (a)–(c) Represent atoms or monoatomic ions as circles; represent molecules or polyatomic ions by overlapping circles for the atoms that make up the molecule or ion; and distinguish among different kinds of atoms by labeling or shading the circles In each case draw representations of at least five nanoscale particles Your diagrams can be two-dimensional (a) A sample of solid lithium nitrate, LiNO3 (b) A sample of molten lithium nitrate (c) A molten sample of lithium nitrate after electrodes have been placed into it and a direct current applied to the electrodes 119 Which sets of values are possible? Why are the others not possible? Explain your reasoning (a) (b) (c) (d) (e) (f ) 116 Draw a diagram to indicate the arrangement of nanoscale particles of each substance Consider each drawing to hold a very tiny portion of each substance Each drawing should contain at least 16 particles, and it need not be three-dimensional Br2(ℓ) LiF(s) 117 Draw diagrams of each nanoscale situation given in parts (a) and (b) Represent atoms or monoatomic ions as circles; represent molecules or polyatomic ions by overlapping circles for the atoms that make up the molecule or ion; and distinguish among different kinds of atoms by labeling or shading the circles In each case draw representations of at least five nanoscale particles Your diagrams can be two-dimensional (a) A crystal of solid sodium chloride (b) The sodium chloride from part (a) after it has been melted Red-numbered questions are answered in Appendix M Atomic Number Number of Protons Number of Neutrons  19 235  53  32  14  40  42  92 131  15   7  18  19  92 131  15   7  18  23 143  79  15   7  40 120 Which sets of values are possible? Why are the others not possible? Explain your reasoning Applying Concepts These questions test conceptual learning Mass Number (a) (b) (c) (d) (e) Mass Number Atomic Number Number of Protons Number of Neutrons  53 195  33  52  35 25 78 16 24 17  25 195  16  24  18  29 117  16  28  17 121 Potassium has three stable isotopes, 39K, 40K, and 41K, but 40K has a very low natural abundance Which of the other two is the more abundant? (No calculation should be necessary.) 122 Lithium has two stable isotopes, 6Li and 7Li The atomic weight of lithium is 6.941 Without doing a calculation, explain which is the more abundant isotope 123 Which member of each pair has the greater number of atoms? Explain why (a) mol Cl or mol Cl2 (b) molecule O2 or mol O2 (c) nitrogen atom or nitrogen molecule (d) 6.032 × 1023 fluorine molecules or mol fluorine ­molecules (e) 20.3 g Ne or mol Ne (f ) molecule Br2 or 159.8 g Br2 (g) 107.9 g Ag or 9.6 g Li (h) 58.9 g Co or 58.9 g Cu (i) g calcium or 6.022 × 1023 calcium atoms (j) g chlorine atoms or g chlorine molecules 124 Which member of each pair has the greater mass? Explain why Unless otherwise noted, all content on this page is © Cengage Learning 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 Questions for Review and Thought (a) mol iron or mol aluminum (b) 6.022 × 1024 lead atoms or mol lead (c) copper atom or mol copper (d) mol Cl or mol Cl2 (e) g oxygen atoms or g oxygen molecules (f ) 23.4 g Mg or mol Mg (g) mol Na or g Na (h) 4.1 g He or 6.022 × 1023 He atoms (i) molecule I2 or mol I2 (j) oxygen molecule or oxygen atom 125 One way to solve problems is to find an analogy between what you know and what you need to determine For example, if you know that the formula of magnesium oxide is MgO, and that sulfur is in Group 6A along with oxygen, by analogy the formula of magnesium sulfide is MgS By analogy with sulfur or phosphorus compounds, name these compounds: (a) Na2SeO3 (c) K3AsO4 (b) AlSbO4 (d) Ag2TeO4 126 When asked to draw all the possible constitutional isomers for C3H8O, a student drew these structures The student’s instructor said some of the structures were identical (a) How many actual isomers are there? (b) Which structures are identical? (i) CH3OCH2OCH2OOH (ii) CH3OCH2OOOCH3 (iii) CH3OOOCH2OCH3 (iv) HO CH2 CH2 CH3 (v) CH3 CH CH3 OH (vi) HO CH CH3 CH3 127 The formula for thallium nitrate is TlNO3 Based on this information, what would be the formulas for thallium carbonate and thallium sulfate? 128 The name given with each of these formulas is incorrect What are the correct names? (a) CaF2, calcium difluoride (b) CuO, copper oxide (c) NaNO3, sodium nitroxide (d) NI3, nitrogen iodide (e) FeCl3, iron(I) chloride (f ) Li2SO4, dilithium sulfate More Challenging Questions hese questions require more thought and integrate several T concepts 129 A high-quality analytical balance can weigh accurately to the nearest 1.0 × 10−4 g A sample of carbon weighed on this balance has a mass of 1.000 mg Calculate the number of carbon atoms in the sample Given the precision of the balance, determine the maximum and minimum number of carbon atoms that could be in the sample Red-numbered questions are answered in Appendix M 90g 130 The element bromine is Br2, so the mass of a Br2 mol­ ecule is the sum of the mass of its two atoms Bromine has two isotopes The mass spectrum of Br2 produces three peaks with relative masses of 157.836, 159.834, and 161.832, and relative heights of 6.337, 12.499, and 6.164, respectively (a) What isotopes of bromine are present in each of the three peaks? (b) What is the mass of each bromine isotope? (c) What is the average atomic mass of bromine? (d) What is the abundance of each of the two bromine isotopes? 131 Uranium is used as a fuel, primarily in the form of uranium(IV) oxide, in nuclear power plants This question considers some uranium chemistry (a) A small sample of uranium metal (0.169 g) is heated to 900 °C in air to give 0.199 g of a dark green oxide, UxOy How many moles of uranium metal were used? What is the empirical formula of the oxide UxOy? What is the name of the oxide? How many moles of UxOy must have been obtained? (b) The oxide UxOy is obtained if UO2NO3 jn H2O is heated to temperatures greater than 800 °C in air However, if you heat it gently, only the water of hydration is lost If you have 0.865 g UO2NO3 jn H2O and obtain 0.679 g UO2NO3 on heating, how many molecules of water of hydration were there in each formula unit of the original compound? 132 A mixture contains only MgSO4 and (NH4)2SO4 If the mass percent of MgSO4 in the mixture is 32.0%, what is the mass percent of sulfate in the mixture? 133 Hemoglobin is an iron-containing protein (molar mass 64,458 g/mol) that is responsible for oxygen transport in our blood Hemoglobin is 0.35% iron by mass Calculate how many iron atoms are in each hemoglobin molecule 134 There are three naturally occurring isotopes of potassium: 39K 38.963707 u; 40K 39.963999 u; and 41K 40.961825 u The average atomic mass of potassium is 39.0983 u and the natural abundance of the lightest isotope is 93.2581% Calculate the natural abundances of the other two isotopes 135 The diatomic compound BrCl is a reddish-brown gas Consider the naturally occurring isotopes of each element: Isotope Br-79 Br-81 Cl-35 Cl-37 Natural Abundance, % 50.69 49.31 75.77 24.23 (a) Name the compound (b) Determine how many different types of BrCl molecules are possible by using the sum of mass numbers as the criterion for type (c) Determine which is the most abundant type in (b) (d) Determine which is the second most abundant type 136 The stainless steel used in the Gateway Arch in St. Louis contains 72.0% Fe, 19.0% Cr, and the remainder is Unless otherwise noted, all content on this page is © Cengage Learning 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 90h Chapter   |  CHEMICAL COMPOUNDS nickel A 10.0-g sample of this stainless steel is treated to convert the metals to their oxides: 10.3 g Fe2O3, 2.71 g Cr2O3, and 1.14 g NiO Calculate the mass percent of each metal in the sample 137 Galinstan, a gallium-indium-tin alloy, is a liquid at room temperature and is used as a nontoxic replacement for mercury in thermometers Its mass ratio of gallium-toindium is 3.186 The mole ratio of indium-to-tin is 2.223 Calculate the mass percent composition of galinstan 138 An adult human body contains 6.0 L blood, which contains about 15.5 g hemoglobin per 100.0 mL blood The molar mass of hemoglobin is approximately 64,500 g/mol and there is mol iron per mol hemoglobin A news item claims that there is sufficient iron in the hemoglobin of the body that this iron, if it were in the form of metallic iron, could make a 3-in iron nail that weighs approximately 3.7 g Show sufficient calculations to either support or refute the claim 139 A 1.546-g sample of magnesium metal is heated in sufficient air at a high temperature so that all of the magnesium reacts The reaction forms 2.512 g MgO and a small quantity of another magnesium-containing compound that is 72.24% magnesium by mass (a) Determine the formula of the other magnesiumcontaining compound (b) Name this compound (c) Calculate what fraction of the original Mg is in this second compound 140 There are four binary potassium compounds of oxygen They contain these mass percents of potassium: Compound I, 83.0%; Compound II, 55.0%; Compound III, 44.9%; and Compound IV, 71.0% One compound has molar mass equal to 110.2 g/mol Use this information to determine the chemical formula of each compound 141 Direct reaction of fluorine with xenon produces three different xenon fluorides One of the compounds, call it compound “I”, contains twice the mass of fluorine as another xenon fluoride Let’s call the latter one compound “II” The third compound, compound “III”, contains 1.5 times the mass of fluorine contained in compound “I” Compound II contains 77.5% Xe (a) Determine the formula of each compound (b) Name each compound 142 A 20.00 g mixture of PCl3 and PCl5 contains 79.50 mass percent chlorine (a) Name each compound (b) Calculate the individual masses of PCl3 and PCl5 in the mixture 143 The present average concentration (mass percent) of magnesium ions in seawater is 0.13% A chemistry textbook estimates that if 1.00 × 108 tons Mg were taken out of the sea each year, it would take one million years for the Mg concentration to drop to 0.12% Do sufficient calculations to either verify or refute this statement Assume that Earth is a sphere with a diameter of 8000 mi, 67% of which is covered by oceans to a depth of mi, and that no Mg is washed back into the oceans at any time Red-numbered questions are answered in Appendix M 144 Through a series of reactions, a 12.3-g sample of potassium carbonate was chemically reacted so that all of its carbon was found in K2Zn3[Fe(CN)6]2 Calculate the mass of K2Zn3[Fe(CN)6]2 formed 145 A 4.22-g mixture of calcium chloride and sodium chloride was treated so that all of the calcium was converted to calcium carbonate This product was then heated, converting it to 0.959 g pure calcium oxide Calculate the mass percent of calcium chloride in the original mixture 146 A certain metal, M, forms two oxides, M2O and MO If the percent by mass of M in M2O is 73.4%, calculate the percent by mass in MO 147 If you heat Al with an element from Group 6A, an ionic compound is formed that contains 18.55% Al by mass (a) What is the likely charge on the nonmetal in the compound formed? (b) Using X to represent the nonmetal, what is the empirical formula for this ionic compound? (c) Which element in Group 6A has been combined with Al? Conceptual Challenge Problems These rigorous, thought-provoking problems integrate concep­ tual learning with problem solving and are suitable for group work CP2.A (Section 2-1) Suppose you are faced with a problem similar to the one faced by Robert Millikan when he analyzed data from his oil-drop experiment The masses of three stacks of dimes are given What you conclude to be the mass of a dime, and what is your argument? Stack = 9.12 g    Stack = 15.96 g    Stack = 27.36 g CP2.B (Section 2-12) The age of the universe is unknown, but some conclude from measuring Hubble’s constant that the age is about 18 billion years old, which is about four times the age of Earth If so, calculate the age of the universe in seconds If you had a sample of carbon with the same number of carbon atoms as there have been seconds since the universe began, determine whether you could measure this sample on a laboratory balance that can detect masses as small as 0.1 mg CP2.C (Section 2-12) A chemist analyzes three compounds and reports these data for the percent by mass of the elements Ex, Ey, and Ez in each compound Compound A B C % Ex % Ey % Ez 37.485 40.002 40.685 12.583  6.7142  5.1216 49.931 53.284 54.193 Assume that you accept the notion that the numbers of atoms of the elements in compounds are in small whole-number ratios and that the number of atoms in a sample of any element is directly proportional to that sample’s mass What is possible for you to know about the empirical formulas for these three compounds? CP2.D (Section 2-12) The table nearby displays on each horizontal row an empirical formula for one of the three compounds noted in CP3.A Unless otherwise noted, all content on this page is © Cengage Learning 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 Questions for Review and Thought Compound A Compound B Compound C ExEy2Ez Ex6Ey8Ez3 Ex3Ey2Ez Ex9Ey2Ez6 ExEy2Ez3 Ex3Ey8Ez3 Based only on what was learned in that problem, determine the empirical formula for each of the other two compounds in that row Red-numbered questions are answered in Appendix M 90i CP2.E (Section 2-12) (a) Suppose that a chemist now determines that the ratio of the masses of equal numbers of atoms of Ez and Ex atoms is 1.3320 g Ez/1 g Ex With this added information, what can now be known about the formulas for compounds A, B, and C in Problem CP2.C? (b) Suppose that this chemist further determines that the ratio of the masses of equal numbers of atoms of Ex and Ey is 11.916 g Ex/1 g Ey Determine the ratio of the masses of equal numbers of Ez and Ey atoms (c) If the mass ratios of equal numbers of atoms of Ex, Ey, and Ez are known, what can be known about the formulas of the three compounds A, B, and C? Unless otherwise noted, all content on this page is © Cengage Learning 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 ... • Nanoscale (models involving particles: atoms, molecules, and ions) • Symbolic (chemical formulas and equations, as well as mathematical equations) These three conceptual levels are explicitly defined... defines half-reactions; balancing redox equations is treated in detail in Appendix F Electrochemical cells, cell potentials, standard half-cell potentials, the relation of cell potential to Gibbs... as media developer, handling OWL and online materials for the book Elizabeth Woods, media developer, ably handled all of the ancillary print materials We also thank Karolina Kiwak, chemistry product