Tài liệu Daniel C. harris quantitative chemical analysis, 8th edition 2010

“The Experiment” by Sempé © C. Charillon, Paris QUANTITATIVE CHEMICAL ANALYSIS Publisher: Clancy Marshall Senior Acquisitions Editor: Jessica Fiorillo Marketing Manager: John Britch Media Editor: Dave Quinn Editorial Assistant: Kristina Treadway Photo Editor: Ted Szczepanski Cover and Text Designer: Vicki Tomaselli Senior Project Editor: Mary Louise Byrd Illustrations: Network Graphics, Precision Graphics Illustration Coordinators: Bill Page, Eleanor Jaekel Production Coordinator: Julia DeRosa Composition and Text Layout: Aptara, Inc. Printing and Binding: RR Donnelley Library of Congress Control Number: 2009943186 ISBN-13: 978-1-4292-1815-3 ISBN-10: 1-4292-1815-0 © 2010, 2007, 2003, 1999 by W. H. Freeman and Company All rights reserved Printed in the United States of America First Printing W. H. Freeman and Company 41 Madison Avenue New York, NY 10010 Houndmills, Basingstoke RG21 6XS, England www.whfreeman.com QUANTITATIVE CHEMICAL ANALYSIS Eighth Edition Daniel C. Harris Michelson Laboratory China Lake, California W. H. Freeman and Company New York This page intentionally left blank BRIEF CONTENTS 0 The Analytical Process 1 1 Chemical Measurements 13 2 Tools of the Trade 29 3 Experimental Error 51 4 Statistics 68 5 Quality Assurance and Calibration Methods 6 Chemical Equilibrium 96 117 7 Activity and the Systematic Treatment of Equilibrium 142 8 Monoprotic Acid-Base Equilibria 162 9 Polyprotic Acid-Base Equilibria 185 10 Acid-Base Titrations 205 11 EDTA Titrations 236 12 Advanced Topics in Equilibrium 258 13 Fundamentals of Electrochemistry 279 18 Applications of Spectrophotometry 419 19 Spectrophotometers 445 20 Atomic Spectroscopy 479 21 Mass Spectrometry 502 22 Introduction to Analytical Separations 537 23 Gas Chromatography 565 24 High-Performance Liquid Chromatography 595 25 Chromatographic Methods and Capillary Electrophoresis 634 26 Gravimetric Analysis, Precipitation Titrations, and Combustion Analysis 673 27 Sample Preparation 699 Notes and References NR1 14 Electrodes and Potentiometry 308 Glossary GL1 15 Redox Titrations 340 Appendixes AP1 16 Electroanalytical Techniques 361 Solutions to Exercises S1 17 Fundamentals of Spectrophotometry Answers to Problems AN1 393 Index I1 v This page intentionally left blank CONTENTS Preface 0 The Analytical Process 1 3-5 Propagation of Uncertainty from Systematic Error The “Most Important” Environmental Data Set of the Twentieth Century 1 4 0-1 Charles David Keeling and the Measurement of Atmospheric CO2 0-2 The Analytical Chemist’s Job 0-3 General Steps in a Chemical Analysis 1 6 11 Box 0-1 Constructing a Representative Sample 12 1 Box 3-2 Keeling’s Exquisitely Precise Measurement of CO2 xiii Chemical Measurements Biochemical Measurements with a Nanoelectrode 1-1 1-2 1-3 1-4 SI Units Chemical Concentrations Preparing Solutions Stoichiometry Calculations for Gravimetric Analysis 1-5 Introduction to Titrations Statistics Is My Red Blood Cell Count High Today? 4-1 Gaussian Distribution 4-2 Confidence Intervals 4-3 Comparison of Means with Student’s t 60 62 68 68 68 73 76 Box 4-1 Choosing the Null Hypothesis in Epidemiology 79 13 16 19 4-4 Comparison of Standard Deviations with the F Test 4-5 t Tests with a Spreadsheet 4-6 Grubbs Test for an Outlier 4-7 The Method of Least Squares 4-8 Calibration Curves 80 82 83 83 87 21 22 4-9 A Spreadsheet for Least Squares 13 13 Box 4-2 Using a Nonlinear Calibration Curve 88 89 Box 1-1 Reagent Chemicals and Primary Standards 23 1-6 Titration Calculations 2 Tools of the Trade Quartz Crystal Microbalance in Medical Diagnosis 2-1 Safe, Ethical Handling of Chemicals and Waste 2-2 The Lab Notebook 2-3 Analytical Balance 2-4 Burets 2-5 Volumetric Flasks 2-6 Pipets and Syringes 2-7 Filtration 2-8 Drying 2-9 Calibration of Volumetric Glassware 2-10 Introduction to Microsoft Excel® 2-11 Graphing with Microsoft Excel Reference Procedure Calibrating a 50-mL Buret 3 Experimental Error Experimental Error 3-1 Significant Figures 3-2 Significant Figures in Arithmetic 3-3 Types of Error Box 3-1 Case Study in Ethics: Systematic Error in Ozone Measurement 3-4 Propagation of Uncertainty from Random Error 24 5 29 Quality Assurance and Calibration Methods The Need for Quality Assurance 97 Box 5-1 Control Charts 99 5-2 Method Validation 49 51 51 51 52 55 55 57 96 5-1 Basics of Quality Assurance 29 30 31 31 35 37 38 40 41 42 43 46 96 Box 5-2 The Horwitz Trumpet: Variation in Interlaboratory Precision 5-3 Standard Addition 5-4 Internal Standards 5-5 Efficiency in Experimental Design 6 Chemical Equilibrium Chemical Equilibrium in the Environment 6-1 The Equilibrium Constant 6-2 Equilibrium and Thermodynamics 6-3 Solubility Product Box 6-1 Solubility Is Governed by More Than the Solubility Product Demonstration 6-1 Common Ion Effect 6-4 Complex Formation Box 6-2 Notation for Formation Constants 6-5 Protic Acids and Bases 6-6 pH 6-7 Strengths of Acids and Bases Demonstration 6-2 The HCl Fountain Box 6-3 The Strange Behavior of Hydrofluoric Acid Box 6-4 Carbonic Acid 100 103 106 109 110 117 117 118 119 121 122 122 124 124 126 128 130 131 132 134 vii 7 Activity and the Systematic Treatment of Equilibrium Hydrated Ions 7-1 The Effect of Ionic Strength on Solubility of Salts Demonstration 7-1 Effect of Ionic Strength on Ion Dissociation Box 7-1 Salts with Ions of Charge ⱖ| 2| Do Not Fully Dissociate 7-2 Activity Coefficients 7-3 pH Revisited 7-4 Systematic Treatment of Equilibrium Box 7-2 Calcium Carbonate Mass Balance in Rivers 7-5 Applying the Systematic Treatment of Equilibrium 219 10-6 Finding the End Point with Indicators 220 Box 10-2 What Does a Negative pH Mean? Demonstration 10-1 Indicators and the Acidity 221 of CO2 142 142 143 Box 10-3 Kjeldahl Nitrogen Analysis Behind the Headlines 143 145 145 149 150 153 223 223 10-7 Practical Notes 10-8 Kjeldahl Nitrogen Analysis 224 225 10-9 The Leveling Effect 10-10 Calculating Titration Curves with Spreadsheets Reference Procedure Preparing Standard Acid and Base 226 235 11 EDTA Titrations 236 236 Ion Channels in Cell Membranes 153 237 11-1 Metal-Chelate Complexes 8 Monoprotic Acid-Base Equilibria Measuring pH Inside Cellular Compartments 8-1 Strong Acids and Bases Box 8-1 Concentrated HNO3 Is Only Slightly Dissociated 8-2 Weak Acids and Bases 8-3 Weak-Acid Equilibria Demonstration 8-1 Conductivity of Weak Electrolytes Box 8-2 Dyeing Fabrics and the Fraction of Dissociation 8-4 Weak-Base Equilibria 8-5 Buffers Box 8-3 Strong Plus Weak Reacts Completely Demonstration 8-2 How Buffers Work 9 viii 163 11-2 11-3 11-4 11-5 238 EDTA EDTA Titration Curves Do It with a Spreadsheet Auxiliary Complexing Agents 240 243 245 246 Box 11-2 Metal Ion Hydrolysis Decreases the Effective Formation Constant for EDTA Complexes 163 165 166 11-6 Metal Ion Indicators Demonstration 11-1 Metal Ion Indicator Color Changes 167 169 11-7 EDTA Titration Techniques Box 11-3 Water Hardness 170 171 174 176 185 Proteins Are Polyprotic Acids and Bases 185 186 Box 9-1 Carbon Dioxide in the Air and Ocean Box 9-2 Successive Approximations 189 191 Diprotic Buffers Polyprotic Acids and Bases Which Is the Principal Species? Fractional Composition Equations Isoelectric and Isoionic pH 193 194 195 197 199 Box 9-3 Isoelectric Focusing 200 10 Acid-Base Titrations 10-1 10-2 10-3 10-4 10-5 162 Polyprotic Acid-Base Equilibria 9-1 Diprotic Acids and Bases 9-2 9-3 9-4 9-5 9-6 162 Box 11-1 Chelation Therapy and Thalassemia 12 Advanced Topics in Equilibrium 12-1 12-2 12-3 12-4 Acid-Base Titration of a Protein 205 Titration of Strong Base with Strong Acid Titration of Weak Acid with Strong Base Titration of Weak Base with Strong Acid Titrations in Diprotic Systems Finding the End Point with a pH Electrode 206 208 210 212 215 Box 10-1 Alkalinity and Acidity 216 249 251 253 258 Acid Rain 258 General Approach to Acid-Base Systems Activity Coefficients Dependence of Solubility on pH Analyzing Acid-Base Titrations with Difference Plots 259 262 265 270 13 Fundamentals of Electrochemistry 279 Lithium-Ion Battery 13-1 Basic Concepts Box 13-1 Ohm’s Law, Conductance, and Molecular Wire 13-2 Galvanic Cells 205 247 249 Demonstration 13-1 The Human Salt Bridge 13-3 Standard Potentials 13-4 Nernst Equation Box 13-2 E° and the Cell Voltage Do Not Depend on How You Write the Cell Reaction Box 13-3 Latimer Diagrams: How to Find E° for a New Half-Reaction 279 280 283 284 286 287 288 290 292 Contents 13-5 E° and the Equilibrium Constant Box 13-4 Concentrations in the Operating Cell 13-6 Cells as Chemical Probes 13-7 Biochemists Use E°⬘ 14 Electrodes and Potentiometry Chem Lab on Mars 14-1 Reference Electrodes 14-2 Indicator Electrodes Demonstration 14-1 Potentiometry with an Oscillating Reaction 14-3 What Is a Junction Potential? 14-4 How Ion-Selective Electrodes Work 14-5 pH Measurement with a Glass Electrode 293 14-6 Ion-Selective Electrodes Box 14-2 Measuring Selectivity Coefficients for an Ion-Selective Electrode Box 14-3 How Was Perchlorate Discovered on Mars? 14-7 Using Ion-Selective Electrodes 14-8 Solid-State Chemical Sensors 15 Redox Titrations Chemical Analysis of High-Temperature Superconductors 15-1 The Shape of a Redox Titration Curve Box 15-1 Many Redox Reactions Are Atom-Transfer Reactions 15-2 Finding the End Point 15-3 15-4 15-5 15-6 15-7 295 297 308 309 311 313 314 317 322 323 324 328 330 331 340 340 341 342 344 345 348 349 350 351 351 How Sweet It Is! 16-1 Fundamentals of Electrolysis Demonstration 16-1 Electrochemical Writing 16-2 Electrogravimetric Analysis 16-3 Coulometry 16-4 Amperometry Box 16-1 Clark Oxygen Electrode Contents 17 Fundamentals of Spectrophotometry The Ozone Hole 17-1 Properties of Light 17-2 Absorption of Light Box 17-1 Why Is There a Logarithmic Relation Between Transmittance and Concentration? Demonstration 17-1 Absorption Spectra 313 Adjustment of Analyte Oxidation State Oxidation with Potassium Permanganate Oxidation with Ce4⫹ Oxidation with Potassium Dichromate Methods Involving Iodine 16 Electroanalytical Techniques 16-6 Karl Fischer Titration of H2O 308 Demonstration 15-1 Potentiometric Titration of Fe2⫹ with MnO4⫺ Box 15-2 Environmental Carbon Analysis and Oxygen Demand Box 15-3 Iodometric Analysis of High-Temperature Superconductors Box 16-3 The Electric Double Layer 293 Box 14-1 Systematic Error in Rainwater pH Measurement: The Effect of Junction Potential Box 16-2 What Is an “Electronic Nose”? 16-5 Voltammetry 352 355 361 361 362 363 367 369 371 371 17-3 17-4 17-5 17-6 Measuring Absorbance Beer’s Law in Chemical Analysis Spectrophotometric Titrations What Happens When a Molecule Absorbs Light? Box 17-2 Fluorescence All Around Us 17-7 Luminescence Box 17-3 Rayleigh and Raman Scattering 372 376 379 385 393 393 394 395 397 398 399 400 403 404 407 408 411 18 Applications of Spectrophotometry 419 Fluorescence Resonance Energy Transfer Biosensor 18-1 Analysis of a Mixture 18-2 Measuring an Equilibrium Constant: The Scatchard Plot 18-3 The Method of Continuous Variation 18-4 Flow Injection Analysis and Sequential Injection 18-5 Immunoassays and Aptamers 18-6 Sensors Based on Luminescence Quenching Box 18-1 Converting Light into Electricity Box 18-2 Upconversion 19 Spectrophotometers Cavity Ring-Down Spectroscopy: Do You Have an Ulcer? 19-1 Lamps and Lasers: Sources of Light Box 19-1 Blackbody Radiation and the Greenhouse Effect 19-2 Monochromators 19-3 Detectors Box 19-2 The Most Important Photoreceptor Box 19-3 Nondispersive Infrared Measurement of CO2 on Mauna Loa 19-4 Optical Sensors 19-5 Fourier Transform Infrared Spectroscopy 19-6 Dealing with Noise 419 419 424 425 427 431 433 434 437 445 445 447 448 450 454 456 460 461 467 472 ix 20 Atomic Spectroscopy 479 An Anthropology Puzzle 479 20-1 An Overview 480 Box 20-1 Mercury Analysis by Cold Vapor Atomic Fluorescence 482 20-2 Atomization: Flames, Furnaces, and Plasmas 20-3 How Temperature Affects Atomic Spectroscopy 20-4 Instrumentation 20-5 Interference 20-6 Inductively Coupled Plasma–Mass Spectrometry 495 497 502 Separated by a Magnetic Field 504 21-2 Oh, Mass Spectrum, Speak to Me! Box 24-4 Choosing Gradient Conditions and Scaling Gradients 509 21-3 Types of Mass Spectrometers 21-4 Chromatography–Mass Spectrometry 512 519 Box 21-4 Matrix-Assisted Laser Desorption/Ionization 527 21-5 Open-Air Sampling for Mass Spectrometry 529 22 Introduction to Analytical Separations 537 Measuring Silicones Leaking from Breast Implants 537 22-1 Solvent Extraction 538 Demonstration 22-1 Extraction with Dithizone 540 Box 22-1 Crown Ethers and Phase Transfer Agents 542 What Is Chromatography? A Plumber’s View of Chromatography Efficiency of Separation Why Bands Spread 542 544 548 554 Box 22-2 Microscopic Description of Chromatography 558 565 What Did They Eat in the Year 1000? 23-1 The Separation Process in Gas Chromatography 565 565 Box 23-1 Chiral Phases for Separating Optical Isomers 570 595 595 596 601 604 606 611 617 623 625 625 25 Chromatographic Methods and Capillary Electrophoresis 634 Capillary Electrochromatography 634 507 Box 21-3 Isotope Ratio Mass Spectrometry x 24-2 Injection and Detection in HPLC 24-3 Method Development for Reversed-Phase Separations 24-4 Gradient Separations 24-5 Do It with a Computer 502 Box 21-1 Molecular Mass and Nominal Mass 504 Box 21-2 How Ions of Different Masses Are 23-2 23-3 23-4 23-5 Box 24-1 Monolithic Silica Columns Box 24-2 Structure of the Solvent–Bonded Phase Interface Box 24-3 “Green” Technology: Supercritical Fluid Chromatography 502 21-1 What Is Mass Spectrometry? 23 Gas Chromatography 24-1 The Chromatographic Process 487 488 493 Droplet Electrospray 22-2 22-3 22-4 22-5 Paleothermometry: How to Measure Historical Ocean Temperatures 482 Box 20-2 GEOTRACES 21 Mass Spectrometry 24 High-Performance Liquid Chromatography 25-1 Ion-Exchange Chromatography 25-2 Ion Chromatography Box 25-1 Surfactants and Micelles 635 642 645 25-3 Molecular Exclusion Chromatography 25-4 Affinity Chromatography 647 649 Box 25-2 Molecular Imprinting 650 Hydrophobic Interaction Chromatography Principles of Capillary Electrophoresis Conducting Capillary Electrophoresis Lab-on-a-Chip: Probing Brain Chemistry 650 650 657 665 25-5 25-6 25-7 25-8 26 Gravimetric Analysis, Precipitation Titrations, and Combustion Analysis 673 The Geologic Time Scale and Gravimetric Analysis 26-1 Examples of Gravimetric Analysis 26-2 Precipitation Demonstration 26-1 Colloids and Dialysis 26-3 26-4 26-5 26-6 26-7 Examples of Gravimetric Calculations Combustion Analysis Precipitation Titration Curves Titration of a Mixture Calculating Titration Curves with a Spreadsheet 26-8 End-Point Detection Demonstration 26-2 Fajans Titration 673 674 676 677 680 682 685 689 690 691 692 Box 23-2 Chromatography Column on a Chip 576 27 Sample Preparation Sample Injection Detectors Sample Preparation Method Development in Gas Chromatography 577 579 584 587 Cocaine Use? Ask the River 699 27-1 Statistics of Sampling 27-2 Dissolving Samples for Analysis 27-3 Sample Preparation Techniques 701 705 710 699 Contents Notes and References Glossary Appendixes A. B. C. D. E. F. G. H. I. J. K. Logarithms and Exponents Graphs of Straight Lines Propagation of Uncertainty Oxidation Numbers and Balancing Redox Equations Normality Solubility Products Acid Dissociation Constants Standard Reduction Potentials Formation Constants Logarithm of the Formation Constant for the Reaction M(aq) ⫹ L(aq) Δ ML(aq) Analytical Standards Solutions to Exercises Answers to Problems Index NR1 GL1 AP1 AP1 AP2 AP3 AP5 AP8 AP9 AP11 AP20 AP28 AP31 AP32 S1 AN1 I1 Experiments Experiments are found at the Web site www.whfreeman.com/qca8e 0. Green Chemistry 1. Calibration of Volumetric Glassware 2. Gravimetric Determination of Calcium as CaC2O4 ⴢ H2O 3. Gravimetric Determination of Iron as Fe2O3 4. Penny Statistics 5. Statistical Evaluation of Acid-Base Indicators 6. Preparing Standard Acid and Base 7. Using a pH Electrode for an Acid-Base Titration 8. Analysis of a Mixture of Carbonate and Bicarbonate 9. Analysis of an Acid-Base Titration Curve: The Gran Plot 10. Fitting a Titration Curve with Excel Solver 11. Kjeldahl Nitrogen Analysis 12. EDTA Titration of Ca2⫹ and Mg2⫹ in Natural Waters 13. Synthesis and Analysis of Ammonium Decavanadate 14. Iodimetric Titration of Vitamin C 15. Preparation and Iodometric Analysis of HighTemperature Superconductor 16. Potentiometric Halide Titration with Ag⫹ 17. Electrogravimetric Analysis of Copper 18. Polarographic Measurement of an Equilibrium Constant 19. Coulometric Titration of Cyclohexene with Bromine 20. Spectrophotometric Determination of Iron in Vitamin Tablets 21. Microscale Spectrophotometric Measurement of Iron in Foods by Standard Addition 22. Spectrophotometric Measurement of an Equilibrium Constant 23. Spectrophotometric Analysis of a Mixture: Caffeine and Benzoic Acid in a Soft Drink 24. Mn2⫹ Standardization by EDTA Titration Contents 25. Measuring Manganese in Steel by Spectrophotometry with Standard Addition 26. Measuring Manganese in Steel by Atomic Absorption Using a Calibration Curve 27. Properties of an Ion-Exchange Resin 28. Analysis of Sulfur in Coal by Ion Chromatography 29. Measuring Carbon Monoxide in Automobile Exhaust by Gas 30. Amino Acid Analysis by Capillary Electrophoresis 31. DNA Composition by High-Performance Liquid Chromatography 32. Analysis of Analgesic Tablets by High-Performance Liquid Chromatography 33. Anion Content of Drinking Water by Capillary Electrophoresis 34. Green Chemistry: Liquid Carbon Dioxide Extraction of Lemon Peel Oil Spreadsheet Topics 2-100 Introduction to Microsoft Excel 2-11 Graphing with Microsoft Excel Problem 3-8 Controlling the appearance of a graph 4-1 Average, standard deviation 4-1 Area under a Gaussian curve (NORMDIST) 4-3 t Distribution (TDIST) Table 4-4 F Distribution (FINV) 4-5 t Test 4-7 Equation of a straight line (SLOPE and INTERCEPT) 4-7 Equation of a straight line (LINEST) 4-9 Spreadsheet for least squares 4-9 Error bars on graphs 5-2 Square of the correlation coefficient, R2 (LINEST) 5-5 Multiple linear regression and experimental design (LINEST) Problem 5-15 Using TRENDLINE 7-5 Solving equations with Excel GOAL SEEK Problem 7-29 Circular reference 8-5 Excel GOAL SEEK and naming cells 10-10 Acid-base titration 11-4 EDTA titrations Problem 11-19 Auxiliary complexing agents in EDTA titrations Problem 11-21 Complex formation 12-1 Using Excel SOLVER 12-2 Activity coefficients with the Davies equation 12-4 Fitting nonlinear curves by least squares 12-4 Using Excel SOLVER for more than one unknown 18-1 Solving simultaneous equations with Excel SOLVER 18-1 Solving simultaneous equations by matrix inversion Problem 23-30 Binomial distribution for isotope patterns (BINOMDIST) 24-5 Computer simulation of a chromatogram 26-7 Precipitation titration curves 43 46 66 70 71 80 81 82 85 86 89 90 101 110 113 158 161 181 226 245 256 256 261 262 272 273 419 422 593 625 690 xi Dan’s grandson Samuel discovers that the periodic table can take you to great places. PREFACE Goals of This Book M y goals are to provide a sound physical understanding of the principles of analytical chemistry and to show how these principles are applied in chemistry and related disciplines— especially in life sciences and environmental science. I have attempted to present the subject in a rigorous, readable, and interesting manner that will appeal to students whether or not their primary interest is chemistry. I intend the material to be lucid enough for nonchemistry majors, yet to contain the depth required by advanced undergraduates. This book grew out of an introductory analytical chemistry course that I taught mainly for nonmajors at the University of California at Davis and from a course for third-year chemistry students at Franklin and Marshall College in Lancaster, Pennsylvania. What’s New? A significant change in this edition that instructors will discover is that the old Chapter 7 on titrations from earlier editions is missing, but its content is dispersed throughout this edition. My motive was to remove precipitation titrations from the critical learning path. Precipitation titrations have decreased in importance and they have not appeared in the last two versions of the American Chemical Society examination in quantitative analysis.* The introduction to titrations comes in Chapter 1. Kjeldahl analysis is grouped with acid-base titrations in Chapter 10. Spectrophotometric titrations appear in Chapter 17 with spectrophotometry. Efficiency in titrimetric experimental design is now with quality assurance in Chapter 5. Precipitation titrations appear with gravimetric analysis in Chapter 26. Gravimetric analysis and precipitation titrations remain self-contained topics that can be covered at any point in the course. A new feature of this edition is a short “Test Yourself” question at the end of each worked example. If you understand the worked example, you should be able to answer the Test Yourself question. Compare your answer with mine to see if we agree. Chapter 0 begins with a biographical account of Charles David Keeling’s measurement of atmospheric carbon dioxide. His results have been described as “the single most important environmental data set taken in the 20th century.” Boxes in Chapters 3 and 19 provide detail on Keeling’s precise manometric and spectrometric techniques. Box 9-1 discusses ocean acidification by atmospheric carbon dioxide. Preindustrial CO2 Present CO2 150 2 × Preindustrial CO2 [CO32− ] (μmol/kg) 120 90 Aragonite solubility limit 60 Calcite solubility limit [CO32− ] 30 0 0 500 1 000 1 500 2 000 Atmospheric CO2 (ppm by volume) Effect of increasing atmospheric CO2 on the ability of marine organisms to make calcium carbonate shells and skeletons (Box 9-1). *P. R. Griffiths, “Whither ‘Quant’? An Examination of the Curriculum and Testing Methods for Quantitative Analysis Courses Taught in Universities and Colleges in the Western USA,” Anal. Bioanal. Chem. 2008, 391, 875. Preface xiii Phoenix Mars Lander discovered perchlorate in Martian soil with ion-selective electrodes (Chapter 14). Polymer backbone N N N N Poly(ethylene glycol) link N + N N N N N Glucose dehydrogenase e− e− PQQ Glucose PQQH2 Gluconolactone “Wired” enzymes described in Section 16-4 are at the heart of sensitive personal blood glucose monitors. Chiral stationary phase separates enantiomers of the drug naproxen by high-performance liquid chromatography (Figure 24-10). xiv Os New boxed applications include biochemical measurements with a nanoelectrode (Chapter 1), the quartz crystal microbalance in medical diagnosis (Chapter 2), a case study of systematic error (Chapter 3), choosing the null hypothesis in epidemiology (Chapter 4), a lab-on-a-chip example of isoelectric focusing (Chapter 9), Kjeldahl nitrogen analysis in the headlines (Chapter 10), lithium-ion batteries (Chapter 13), measuring selectivity coefficients of ion-selective electrodes (Chapter 14), how perchlorate was discovered on Mars (Chapter 14), an updated description of the Clark oxygen electrode (Chapter 16), Rayleigh and Raman scattering (Chapter 17), spectroscopic upconversion (Chapter 18), trace elements in the ocean (Chapter 20), phase transfer agents (Chapter 22), gas chromatography on a chip (Chapter 23), paleothermometry (Chapter 24), structure of the solventbonded phase interface (Chapter 24), and measuring illicit drug use by analyzing river water (Chapter 27). Spreadsheet instructions are updated to Excel 2007, but instructions for earlier versions of Excel are retained. A new section in Chapter 2 describes how electronic balances work. Rectangular and triangular uncertainty distributions for systematic error are introduced in Chapter 3. Chapter 4 includes discussion of standard deviation of the mean and “tails” in probability distributions. The Grubbs test replaces the Dixon Q test for outliers in Chapter 4. Reporting limits are illustrated with trans fat analysis in food in Chapter 5. Elementary discussion of the systematic treatment of equilibrium in Chapter 7 is enhanced with a discussion of ammonia acid-base chemistry. Chapter 8 and the appendix now include N N N pKa for acids at an ionic strength of 0.1 M in addition to an ionic strength of 0. Discussion of selectivity coefficients was N N N improved in Chapter 14 and the iridium oxide pH electrode is Os − introduced. “Wired” enzymes and mediators for coulometric e e− blood glucose monitoring are described in Chapter 16. Voltammetry in Chapter 16 now includes a microelectrode array for biological measurements. There is a completely new section on flow injection analysis and sequential injection in Chapter 18, and these techniques appear again in later examCarbon ples. Chapter 19 on spectrophotometers is heavily updated. electrode Laser-induced breakdown and dynamic reaction cells for atomic spectrometry are introduced in Chapter 20. Mass spectrometry in Chapter 21 now includes the linear ion trap and the orbitrap, electron-transfer dissociation for protein sequencing, and open-air sampling methods. Numerous chromatography updates are found throughout Chapters 22–25. Stir-bar sorption was added to sample preparation in Chapter 23. Polar embedded group stationary phases, hydrophilic interaction chromatography, and the charged aerosol detector were added to Chapter 24. There is a discussion of the linear solvent strength model in liquid chromatography and a new section that teaches how to use a spreadsheet to predict the effect of solvent composition in isocratic elution. The supplement at www.whfreeman.com/qca gives a spreadsheet for simulating gradient elution. Chapter 25 describes hydrophilic interaction chromatography for ion exchange, hydrophobic interaction chromatography for protein purification, analyzing heparin Interaction of (R)- and (S)-naproxen with (S,S) stationary phase contamination by electrophoresis, wall charge control in elecNaphthalene trophoresis, an update group on DNA sequencing by electrophoresis, Dinitrophenyl and microdialysis/ group (S )-Naproxen electrophoresis of (R)-Naproxen (S,S) (S,S) neurotransmitters More stable adsorbate Less stable adsorbate with a lab-on-a-chip. Data from a roundrobin study of precision and accuracy of combustion analysis are included in Chapter 26. The 96-well plate for solid-phase extraction sample preparation was added to Chapter 27. Preface Servo amplifier Null position sensor Balance pan Force-transmitting lever Internal calibration mass Coil frame Load receptor Wire coil Parallel guides Permanent magnet S NN S Firm anchor Coil frame Firm anchor Mechanical force Electromagnetic force Wire coil N Analogto-digital converter Balance display 122.57 g S Precision resistor Microprocessor There is a new discussion of the operation of an electronic balance in Chapter 2, Tools of the Trade. Applications A basic tenet of this book is to introduce and illustrate topics with concrete, interesting examples. In addition to their pedagogic value, Chapter Openers, Boxes, Demonstrations, and Color Plates are intended to help lighten the load of a very dense subject. I hope you will find these features interesting and informative. Chapter Openers show the relevance of analytical chemistry to the real world and to other disciplines of science. I can’t come to your classroom to present Chemical Demonstrations, but I can tell you about some of my favorites and show you color photos of how they look. Color Plates are located near the center of the book. Boxes discuss interesting topics related to what you are studying or amplify points in the text. Problem Solving Nobody can do your learning for you. The two most important ways to master this course are to work problems and to EXAM PLE How Many Tablets Should We Analyze? gain experience in the laboratory. Worked Examples are a In a gravimetric analysis, we need enough product to weigh accurately. Each tablet principal pedagogic tool designed to teach problem solving provides ⬃15 mg of iron. How many tablets should we analyze to provide 0.25 g of Fe2O3? and to illustrate how to apply what you have just read. Each worked example ends with a Test Yourself question that ⴢ ⴢ asks you to apply what you learned in the example. ⴢ Exercises are the minimum set of problems that apply most Test Yourself If each tablet provides ⬃20 mg of iron, how many tablets should we major concepts of each chapter. Please struggle mightily analyze to provide ⬃0.50 g of Fe2O3? (Answer: 18) with an Exercise before consulting the solution at the back of the book. Problems at the end of the chapter cover the entire content of the book. Short answers to numerical problems are at the back of the book and complete solutions appear in the Solutions Manual that can be made available for purchase if your instructor so chooses. B C D A Spreadsheets are indispensable tools for sci1 Mg(OH) Solubility 2 ence and engineering. You can cover this book Spreadsheets are introduced as an 2 without using spreadsheets, but you will never important problem-solving tool. _ _ 3 _ 3 Ksp = [OH ]guess = [OH ] /(2 + K1[OH ]) = regret taking the time to learn to use them. The 7.1E-12 0.0002459 7.1000E-12 4 text explains how to use spreadsheets and some K1 = 5 problems ask you to apply them. If you are com[Mg2+] = [MgOH+] = 6 3.8E+02 Set cell: D4 fortable with spreadsheets, you will use them 0.0001174 0.0000110 7 To value: 7.1E-12 even when the problem does not ask you to. A 8 few of the powerful built-in features of Microsoft By changing cell: C4 D4 = C4^3/(2+A6*C4) 9 Excel are described as they are needed. These 10 C7 = A4/C4^2 OK Cancel features include graphing in Chapters 2 and 4, 11 D8 = A6*C7*C4 statistical functions and regression in Chapter 4, Preface xv multiple regression for experimental design in Chapter 5, solving equations with Goal Seek in Chapters 7, 8, and 12, Solver in Chapters 12 and 18, and matrix operations in Chapter 18. Other Features of This Book Terms to Understand Essential vocabulary, highlighted in bold in the text, is collected at the end of the chapter. Other unfamiliar or new terms are italic in the text, but not listed at the end of the chapter. Glossary All bold vocabulary terms and many of the italic terms are defined in the glossary. Appendixes Tables of solubility products, acid dissociation constants, redox potentials, and formation constants appear at the back of the book. You will also find discussions of logarithms and exponents, equations of a straight line, propagation of error, balancing redox equations, normality, and analytical standards. Notes and References Citations in the chapters appear at the end of the book. Supplements WebAssign Premium logo. The Solutions Manual for Quantitative Chemical Analysis (ISBN 1-4292-3123-8) contains complete solutions to all problems. The student Web site, www.whfreeman.com/qca8e, has directions for experiments, which may be reproduced for your use. “Green chemistry” is introduced in Chapter 2 of the textbook and “green profiles” of student experiments are included in the instructions for experiments at the Web site. There are instructions for two new experiments on fitting an acidbase titration curve with a spreadsheet and liquid carbon dioxide extraction of lemon peel oil. At the Web site, you will also find lists of experiments from the Journal of Chemical Education. Supplementary topics at the Web site include spreadsheets for precipitation titrations, microequilibrium constants, spreadsheets for redox titrations curves, analysis of variance, and spreadsheet simulation of gradient liquid chromatography. Online quizzing helps students reinforce their understanding of the chapter content. The instructors’ Web site, www.whfreeman.com/qca8e, has all artwork and tables from the book in preformatted PowerPoint slides and as JPG files, an online quizzing gradebook, and more. For instructors interested in online homework management, W. H. Freeman and WebAssign have partnered to deliver WebAssign Premium. WebAssign Premium combines over 600 questions with a fully interactive DynamicBook at an affordable price. To learn more or sign up for a faculty demo account, visit www.webassign.net. DynamicBook for Quantitative Chemical Analysis, Eighth Edition, is an electronic version of the text that gives you the flexibility to fully tailor content to your presentation of course material. It can be used in conjunction with the printed text, or it can be adopted on its own. Please go to www.dynamicbooks.com for more information, or speak with your W. H. Freeman sales representative. The People A book of this size and complexity is the work of many people. Jodi Simpson—the most thoughtful and meticulous copy editor—read every word with a critical eye and improved the exposition in innumerable ways. At W. H. Freeman and Company, Jessica Fiorillo provided overall guidance and was especially helpful in ferreting out opinions from instructors. Mary Louise Byrd shepherded the manuscript through production with her magic wand. Kristina Treadway managed the process of moving the book into production, and Anthony Petrites coordinated the reviewing of every chapter. Ted Sczcepanski located several hard-to-find photographs for the book. Dave Quinn made sure that the supplements were out on time and that the Web site was up and running with all its supporting resources active. Katalin Newman, at Aptara, did an outstanding job of proofreading. At the Scripps Institution of Oceanography, Ralph Keeling, Peter Guenther, David Moss, Lynne Merchant, and Alane Bollenbacher shared their knowledge of atmospheric CO2 measurements and graciously provided access to Keeling family photographs. I am especially delighted to have had feedback from Louise Keeling on my story of her husband, Charles David Keeling. This material opens the book in Chapter 0. Sam Kounaves of Tufts University xvi Preface devoted a day to telling me about the Phoenix Mars Lander Wet Chemistry Laboratory, which is featured in Chapter 14. Jarda Ruzika of the University of Washington brought the importance of flow injection and sequential injection to my attention, provided an excellent tutorial, and reviewed my description of these topics in Chapters 18 and 19. David Sparkman of the University of the Pacific had detailed comments and suggestions for Chapter 21 on mass spectrometry. Joerg Barankewitz of Sartorius AG provided information and graphics on balances that you will find in Chapter 2. Solutions to problems and exercises were checked by two wonderfully careful students, Cassandra Churchill and Linda Lait of the University of Lethbridge in Canada. Eric Erickson and Greg Ostrom provided helpful information and discussions at Michelson Lab. My wife, Sally, works on every aspect of every edition of this book and the Solutions Manual. She contributes mightily to whatever clarity and accuracy we have achieved. In Closing This book is dedicated to the students who use it, who occasionally smile when they read it, who gain new insight, and who feel satisfaction after struggling to solve a problem. I have been successful if this book helps you develop critical, independent reasoning that you can apply to new problems. I truly relish your comments, criticisms, suggestions, and corrections. Please address correspondence to me at the Chemistry Division (Mail Stop 6303), Research Department, Michelson Laboratory, China Lake CA 93555. Acknowledgments I am indebted to many people who asked questions and provided suggestions and new information for this edition. They include Robert Weinberger (CE Technologies), Tom Betts (Kutztown University), Paul Rosenberg (Rochester Institute of Technology), Barbara Belmont (California State University, Dominguez Hills), David Chen (University of British Columbia), John Birks (2B Technologies), Bob Kennedy (University of Michigan), D. Brynn Hibbert (University of New South Wales), Kris Varazo (Francis Marion University), Chongmok Lee (Ewha Womans University, Korea), Michael Blades (University of British Columbia), D. J. Asa (ESA, Inc.), F. N. Castellano and T. N. Singh-Rachford (Bowling Green State University), J. M. Kelly and D. Ledwith (Trinity College, University of Dublin), Justin Ries (University of North Carolina), Gregory A. Cutter (Old Dominion University), Masoud Agah (Virginia Tech), Michael E. Rybak (U.S. Centers for Disease Control and Prevention), James Harnly (U.S. Department of Agriculture), Andrew Shalliker (University of Western Sydney), R. Graham Cooks (Purdue University), Alexander Makarov (Thermo Fisher Scientific, Bremen), Richard Mathies (University of California, Berkeley), A. J. Pezhathinal and R. Chan-Yu-King (University of Science and Arts of Oklahoma), Peter Licence (University of Nottingham), and Geert Van Biesen (Memorial University of Newfoundland). People who reviewed parts of the eighth edition manuscript or who reviewed the seventh edition to make suggestions for the eighth edition include Rosemari Chinni (Alvernia College), Shelly Minteer (St. Louis University), Charles Cornett (University of Wisconsin–Platteville), Anthony Borgerding (St. Thomas College), Jeremy Mitchell-Koch (Emporia State University), Kenneth Metz (Boston College), John K. Young (Mississippi State University), Abdul Malik (University of Southern Florida), Colin F. Poole (Wayne State University), Marcin Majda (University of California, Berkeley), Carlos Garcia (University of Texas, San Antonio), Elizabeth Binamira-Soriaga (Texas A&M University), Erin Gross (Creighton University), Dale Wood (Bishop’s University), Xin Wen (California State University, Los Angeles), Benny Chan (The College of New Jersey), Pierre Herckes (Arizona State University), Daniel Bombick (Wright State University), Sidney Katz (Rutgers University), Nelly Matteva (Florida A&M University), Michael Johnson (University of Kansas), Dmitri Pappas (Texas Tech University), Jeremy Lessmann (Washington State University), Alexa Serfis (Saint Louis University), Stephen Wolf (Indiana State University), Stuart Chalk (University of North Florida), Barry Lavine (Oklahoma State University), Katherine Pettigrew (George Mason University), Blair Miller (Grand Valley State University), Nathalie Wall (Washington State University), Kris Varazo (Francis Marion University), Carrie Brennan (Austin Peay State University), Lisa Ponton (Elon University), Feng Chen (Rider University), Eric Ball (Metropolitan State College of Denver), Russ Barrows (Metropolitan State College of Denver), and Mary Sohn (Florida Institute of Technology). 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