Fundamentals of
AIMALYTICAL C H E M I S T R Y
Seventh Edition
Douglas A. Skoog Stanford University
Donald M. West San Jose State University
F. James Holler University ;of Kentucky
W r
SAUNDERS COLLEGE PUBLISHING Harcourt Brace College Publishers
Fort Worth Philadelphia San Diego New York Orlando Austin San Antonio Toronto
Montreal London Sydney Tokyo
Contents
i
4
Introduction 1
1A Role of Analytical Chemistry in the Sciences 7
1B Classification of Quantitative Methods of Analysis 2
1C Steps in a Typical Quantitative Analysis 3
Errors in Chemical Analyses 11
2A Definition of Terms 12
2B Systematic Errors 16
2C Questions and Problems 20
Random Errors in Analyses 21
3A The Nature of Random Errors 21
3B The Statistical Treatment of Random Error 25
3C The Standard Deviation of Computed Results 33
3D Methods for Reporting Computed Data 39
3E Questions and Problems 44
Application of Statistics to Data Treatment and Evaluation
4A Confidence Limits 47
4B Statistical Aids to Hypothesis Testing 51
4C Detection of Gross Errors 57
4D Estimation of Detection Limits 59
4E The Least-Squares Method for Deriving Calibration Plots
4F Quality Assurance and Control Charts 65
4G Questions and Problems 68
Gravimetrie Methods of Analysis 71
5A Gravimetrie Calculations 73
5B Properties of Precipitates and Precipitating Agents 82
5C Drying and Ignition of Precipitates 92
5D Application of Gravimetrie Methods 93
5E Questions and Problems 97
xii Contents
7
8
10
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Titrimetric Methods of Analysis 700
6A Some General Aspects of Volumetrie Titrimetry 100
6B Standard Solutions 702
6C Volumetrie Caiculations 103
6D Gravimetrie Titrimetry 7 77
6E Questions and Problems 7 78
Aqueous-Solution Chemistry 722
7A The Chemical Composition ofAqueous Solutions 722
7B Chemical Equilibrium 126
7C Questions and Problems 746
Effect of Electrolytes on lonic Equilibria 148
8A Thermodynamic Versus Concentration-Based Equilibrium Consta nts 748
8B Activity Coefficients 757
8C Questions and Problems 758
Application of Equilibrium Caiculations to Complex Systems 159
9A A Systematic Method for Solving Multiple-Equilibrium Problems 760
9B The Calculation of Solubility by the Systematic Method 764
9C Separation of Ions by Control of the Concentration of the Precipitating Agent 783
9D Questions and Problems 787
Theory of Neutralization Titrations 189
10A Solutions and Indicators for Acid/Base Titrations 789
10B Titration Curves 792
10C Titration Curves for Strong Acids and Strong Bases 794
10D Buffer Solutions 200
10E Titration Curves for Weak Acids 270
10F Titration Curves for Weak Bases 274
10G The Composition of Buffer Solutions as a Function of pH 276
10H Common Types of Acid/Base Indicators 278
101 Questions and Problems 227
Titration Curves for Complex Acid/Base Systems 224
11A Mixtures of Strong and Weak Acids or Strong and Weak Bases 224
I IB Polyfunctional Acids 228
11C Polyfunctional Bases 228
11D Buffer Solutions Involving Polyprotic Acids 229
Contents xii i
1 9 1Z
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11E Caiculation of the pH of Solutions of Amphiprotic Salts 231
11F Titration Curves for Polyfunctional Acids 234
11G Titration Curves for Polyfunctional Bases 240
11H Titration Curves for Amphiprotic Species 247
111 The Composition of Solutions of a Polyprotic Acid as a Function of pH 243
11J Questions and Problems 245
Applications of Neutralization Titrations 248
12A Reagents for Neutralization Titrations 248
12B Typical Applications of Neutralization Titrations 254
12C Questions and Problems 262
Precipitation Titrimetry 266
13A Titration Curves 266
13B End Points for Argentometric Titrations 270
13C Applications of Standard Silver Nitrate Solutions 275
13D Questions and Problems 275
Complex-Formation Titrations 278
14A Complex-Formation Reactions 278
14B Titrations with Aminocarboxylic Acids 279
14C Titrations with Inorganic Complexing Agents 300
14D Questions and Problems 507
An Introduction to Electrochemistry 303
15A Oxidation/Reduction Reactions 303
15B Electrochemical Cells 307
15C Electrode Potentials 377
15D Questions and Problems 327
Applications of Standard Electrode Potentials 330
16A The Thermodynamic Potential of Electrochemical Cells 330
16B Calculations of Redox Equilibrium Constants 338
16C Redox Titration Curves 343
16D Oxidation/Reduction Indicators 354
16E Potentiometrie End Points 358
16F Questions and Problems 358
Applications of Oxidation/Reduction Titrations 360
17A Auxiliary Oxidizing and Reducing Reagents 360
17B Application of Standard Reductants 362
xiv Contents
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19
20
21
22
17C Applications of Standard Oxidants 366
17D Some Specialized Oxidants 375
17E Questions and Problems 383
Theory of Potent iometry 386
18A General Principles 386
18B Reference Electrodes 387
18C Liquid-Junction Potentials 389
18D Indicator Electrodes 390
18E Questions and Problems 470
Applications of Potent iometry 412
19A Instruments for Measuring Cell Potentials 412
19B Direct Potentiometrie Measurements 475
19C Potentiometrie Titrations 423
19D The Determination of Equilibrium Constants from Electrode Potential Measurements 427
19E Questions and Problems 429
Electrogravimetric and Coulometric Methods 431
20A The Effect of Current on the Potential of Electrochemical Cells 431
20B The Potential Selectivity of Electrolytic Methods 439
20C Electrogravimetric Methods ofAnalysis 440
20D Coulometric Methods of Analysis 446
20E Questions and Problems 457
Voltammetry 460
21A Excitation Signals in Voltammetry 467
21B Linear-Scan Voltammetry 462
21C Pulse Polarographic and Voltammetric Methods 486
21D Stripping Methods 490
21E Voltammetry with Ultramicroelectrodes 494
21F Questions and Problems 495
An Introduct ion to Spectrochemical Methods 497
22A General Properties of Electromagnetic Radiation 497
22B The Electromagnetic Spectrum 507
22C Absorption of Radiation 502
22D Emission of Electromagnetic Radiation 573
22E Questions and Problems 524
Contents xv
24
25
26
7
28
29
Instruments for Optical Spectrometry 527
23A Instrument Components 527
23B Optical Instrument Designs 550
23C Questions and Problems 555
Molecular Absorption Spectroscopy 557
24A Ultraviolet and Visible Molecular Absorption Spectroscopy 557
24B Automated Photometrie and Spectrophotometric Methods 587
24C Infrared Absorption Spectroscopy 592
24D Questions and Problems 598
Molecular Fluorescence Spectroscopy 607
25A Theory of Molecular Fluorescence 607
25B Effect of Concentration on Fluorescence Intensity 605
25C Fluorescence Instruments 606
25D Applications of Fluorescence Methods 607
25E Questions and Problems 609
Atomic Spectroscopy Based on Ultraviolet and Visible Radiation 67 7
26A Sources of Atomic Spectra 67 7
26B Atomic Spectroscopy Based upon Flame Atomization 672
26C Atomic Spectroscopy with Electrothermal Atomizers 626
26D Atomic Emission Methods Based on Plasma Sources 632
26E Questions and Problems 635
Kinetic Methods of Analysis 637
27'A Rates of Chemical Reactions: Rate Laws 638
27B The Determination of Reaction Rates 648
27C Applications of Kinetic Methods 655
27D Questions and Problems 658
An Introduction to Chromatographie Methods 660
28A A General Description of Chromatography 660
28B Migration Rates of Solutes 663
28C Band Broadening and Column Efficiency 666
28D Column Resolution 676
28E Applications of Chromatography 682
28F Questions and Problems 684
Gas-Liquid Chromatography 686
29A Instruments for Gas-Liquid Chromatography 687
29B Gas-Chromatographie Columns and the Stationary Phase 693
xvi Contents
30
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29C Applications of Gas-Liquid Chromatography 698
29D Gas-Solid Chromatography 699
29E Questions and Problems 699
High-Performance Liquid Chromatography 707
30A Instruments 703
30B High-Performance Partition Chromatography 708
30C High-Performance Adsorption Chromatography 770
30D High-Performance Ion-Exchange Chromatography 770
30E High-Performance Size-Exclusion Chromatography 774
30F Comparison of High-Performance Liquid Chromatography with Gas-Liquid Chromatography 777
30G Supercritical-Fluid Chromatography 778
30H Planar Chromatography 727
301 Questions and Problems 724
The Analysis of Real Samples 725
31A Choice of Method for the Analysis of Real Samples 727
31B The Accuracy Obtainable in the Analysis of Complex Materials 732
Preparing Samples for Analysis 736
32A Sampling 736
32B Moisture in Samples 744
32C The Determination of Water in Samples 747
32D Questions and Problems 748
Decomposing and Dissolving the Sample 749
33A Sources of Errors in Decompositipn and Dissolution 749
33B Decomposing Samples by Inorganic Acids in Open Vessels 750
33C Microwave Decompositions 752
33D Combustion Methods for Decomposing Organic Samples 754
33E Decomposition of Inorganic Materials by Fluxes 756
33F Questions and Problems 759
Eliminating Interferences 760
34A The Nature of the Separation Process 760
34B Separation by Precipitation 767
34C Separation by Extraction 764
34D Application of Extraction Procedures 769
34E Ion-Exchange Separations 774
34F The Separation of Inorganic Species by Distillation 775
34G Questions and Problems 776
Contents xvii
1 ^ 1 I
36
The Chemicals, Apparatus , and Uni t Operat ions of Analyt ical
Chemistry 778
35A The Selection and Handling of Reagents and Other Chemicals 778
35B The Cleaning and Mark ing of Laboratory Ware 779
35C The Evaporation of Liquids 780
35D The Measurement of Mass 780
35E The Equipment and Manipulat ions Associated w i t h Weigh ing 787
35F Weigh t Titrations 790
35G The Equipment and Manipulat ions for Fil tration and Igni t ion 797
35H The Measurement of Volume 798
351 The Calibration of Volumetr ie Ware 806
35J The Laboratory Notebook 808
35K Safety in the Laboratory 870
Selected M e t h o d s of Analysis 812
36A Gravimetrie Methods of Analysis 813
36B Neutral izat ion Titrat ions 878
36C Precipitation Titrat ions 827
36D Complex-Formation Titrat ions w i t h EDTA 830
36E Titrat ions w i t h Potassium Permanganate 833
36F Ti t rat ion w i t h lodine 839
36G Titrat ions w i t h Sodium Thiosulfate 847
36H Titrat ions w i t h Potassium Bromate 844
361 Potentiometr ie Methods 846
36J Electrogravimetric Methods 852
36K Coulometric Titrat ions 854
36L Vol tammetry 855
36M Methods Based on the Absorpt ion of Radiation 858
36N Molecular Fluorescence 862
360 Atomic Spectroscopy 863
36P Applicat ions of Ion-Exchange Resins 866
36Q Gas-Liquid Chromatography 868
Glossary G-7
j Selected References to the Literature of Analytical Chemistry A-
A P P E N D I X 2 Solubility Product Constants A-6
A P P E N D I X o Dissociation Constants for Acids A-8
A P P E N D I X
3
xviii Contents
A P P E N D I X A Stepwise Formation Constants A-10
A P P E N D I X c Some Standard and Formal Electrode Potentials A-12
A P P E N D I X /r Designations Carried by Ashless Filter Papers A-16
A P P E N D I X -i Designations and Porosities for Filtering Crucibles A-17
A P P E N D I X Q Use of Exponential Numbers and Logarithms A-18
A P P E N D I X Q Volumetrie Caiculations Using Normality and Equivalent Weight A-23
A P P E N D I X | Q Compounds Recommended for the Preparation of Standard Solutions of Common Elements A-32
A P P E N D I X | i Propagation of Measurement Uncertainties A-34
Answers to Selected Questions and Problems A-40
Index 1-1