Sách Chemistry Modern Analytical Chemistry

Preface xii

Chapter 1

Introduction 1

1A What is Analytical Chemistry? 2

1B The Analytical Perspective 5

1C Common Analytical Problems 8

1D Key Terms 9

1E Summary 9

1F Problems 9

1G Suggested Readings 10

1H References 10

Chapter 2

Basic Tools of Analytical Chemistry 11

2A Numbers in Analytical Chemistry 12

2A.1 Fundamental Units of Measure 12

2A.2 Significant Figures 13

2B Units for Expressing Concentration 15

2B.1 Molarity and Formality 15

2B.2 Normality 16

2B.3 Molality 18

2B.4 Weight, Volume, and Weight-to-Volume

Ratios 18

2B.5 Converting Between Concentration Units 18

2B.6 p-Functions 19

2C Stoichiometric Calculations 20

2C.1 Conservation of Mass 22

2C.2 Conservation of Charge 22

2C.3 Conservation of Protons 22

2C.4 Conservation of Electron Pairs 23

2C.5 Conservation of Electrons 23

2C.6 Using Conservation Principles in

Stoichiometry Problems 23

2D Basic Equipment and Instrumentation

2D.1 Instrumentation for Measuring Mas

2D.2 Equipment for Measuring Volume

2D.3 Equipment for Drying Samples 29

2E Preparing Solutions 30

2E.1 Preparing Stock Solutions 30

2E.2 Preparing Solutions by Dilution 31

2F The Laboratory Notebook 32

2G Key Terms 32

2H Summary 33

2I Problems 33

2J Suggested Readings 34

2K References 34

Chapter 3

The Language of Analytical Chemis

3A Analysis, Determination, and Measurem

3B Techniques, Methods, Procedures, and

Protocols 36

3C Classifying Analytical Techniques 37

3D Selecting an Analytical Method 38

3D.1 Accuracy 38

3D.2 Precision 39

3D.3 Sensitivity 39

3D.4 Selectivity 40

3D.5 Robustness and Ruggedness 42

3D.6 Scale of Operation 42

3D.7 Equipment, Time, and Cost 44

3D.8 Making the Final Choice 44

4E.4 Errors in Significance Testing 84

4F Statistical Methods for Normal Distribution

4F.1 Comparing

–

Xto µ 85

4F.2 Comparing s

2

to σ2

87

4F.3 Comparing Two Sample Variances 88

4F.4 Comparing Two Sample Means 88

4F.5 Outliers 93

4G Detection Limits 95

4H Key Terms 96

4I Summary 96

4J Suggested Experiments 97

4K Problems 98

4L Suggested Readings 102

4M References 102

Chapter 5

Calibrations, Standardizations,

and Blank Corrections 104

5A Calibrating Signals 105

5B Standardizing Methods 106

5B.1 Reagents Used as Standards 106

5B.2 Single-Point versus Multiple-Point

Standardizations 108

5B.3 External Standards 109

5B.4 Standard Additions 110

5B.5 Internal Standards 115

5C Linear Regression and Calibration Curves

5C.1 Linear Regression of Straight-Line Calib

Curves 118

5C.2 Unweighted Linear Regression with Err

in y 119

5C.3 Weighted Linear Regression with Error

in y 124

5C.4 Weighted Linear Regression with Error

in Both xand y 127

5C.5 Curvilinear and Multivariate

Regression 127

5D Blank Corrections 128

5E Key Terms 130

5F Summary 130

5G Suggested Experiments 130

5H Problems 131

5I Suggested Readings 133

5J References 134

3E Developing the Procedure 45

3E.1 Compensating for Interferences 45

3E.2 Calibration and Standardization 47

3E.3 Sampling 47

3E.4 Validation 47

3F Protocols 48

3G The Importance of Analytical Methodology 48

3H Key Terms 50

3I Summary 50

3J Problems 51

3K Suggested Readings 52

3L References 52

Chapter 4

Evaluating Analytical Data 53

4A Characterizing Measurements and Results 54

4A.1 Measures of Central Tendency 54

4A.2 Measures of Spread 55

4B Characterizing Experimental Errors 57

4B.1 Accuracy 57

4B.2 Precision 62

4B.3 Error and Uncertainty 64

4C Propagation of Uncertainty 64

4C.1 A Few Symbols 65

4C.2 Uncertainty When Adding or Subtracting 65

4C.3 Uncertainty When Multiplying or

Dividing 66

4C.4 Uncertainty for Mixed Operations 66

4C.5 Uncertainty for Other Mathematical

Functions 67

4C.6 Is Calculating Uncertainty Actually Useful? 68

4D The Distribution of Measurements and

Results 70

4D.1 Populations and Samples 71

4D.2 Probability Distributions for Populations 71

4D.3 Confidence Intervals for Populations 75

4D.4 Probability Distributions for Samples 77

4D.5 Confidence Intervals for Samples 80

4D.6 A Cautionary Statement 81

4E Statistical Analysis of Data 82

4E.1 Significance Testing 82

4E.2 Constructing a Significance Test 83

4E.3 One-Tailed and Two-Tailed Significance

Tests 84

Obtaining and Preparing Sam

for Analysis 179

7A The Importance of Sampling 180

7B Designing a Sampling Plan 182

7B.1 Where to Sample the Target

Population 182

7B.2 What Type of Sample to Collect

7B.3 How Much Sample to Collect 1

7B.4 How Many Samples to Collect 1

7B.5 Minimizing the Overall Variance

7C Implementing the Sampling Plan 19

7C.1 Solutions 193

7C.2 Gases 195

7C.3 Solids 196

7D Separating the Analyte from

Interferents 201

7E General Theory of Separation

Efficiency 202

7F Classifying Separation Techniques 2

7F.1 Separations Based on Size 205

7F.2 Separations Based on Mass or Den

7F.3 Separations Based on Complexati

Reactions (Masking) 207

7F.4 Separations Based on a Change

of State 209

7F.5 Separations Based on a Partitionin

Phases 211

7G Liquid–Liquid Extractions 215

7G.1 Partition Coefficients and Distrib

Ratios 216

7G.2 Liquid–Liquid Extraction with N

Reactions 216

7G.3 Liquid–Liquid Extractions Involv

Acid–Base Equilibria 219

7G.4 Liquid–Liquid Extractions Involv

Chelators 221

7H Separation versus Preconcentration

7I Key Terms 224

7J Summary 224

7K Suggested Experiments 225

7L Problems 226

7M Suggested Readings 230

7N References 231

Equilibrium Chemistry 135

6A Reversible Reactions and Chemical

Equilibria 136

6B Thermodynamics and Equilibrium

Chemistry 136

6C Manipulating Equilibrium Constants 138

6D Equilibrium Constants for Chemical

Reactions 139

6D.1 Precipitation Reactions 139

6D.2 Acid–Base Reactions 140

6D.3 Complexation Reactions 144

6D.4 Oxidation–Reduction Reactions 145

6E Le Châtelier’s Principle 148

6F Ladder Diagrams 150

6F.1 Ladder Diagrams for Acid–Base Equilibria 150

6F.2 Ladder Diagrams for Complexation

Equilibria 153

6F.3 Ladder Diagrams for Oxidation–Reduction

Equilibria 155

6G Solving Equilibrium Problems 156

6G.1 A Simple Problem: Solubility of Pb(IO3)2in

Water 156

6G.2 A More Complex Problem: The Common Ion

Effect 157

6G.3 Systematic Approach to Solving Equilibrium

Problems 159

6G.4 pH of a Monoprotic Weak Acid 160

6G.5 pH of a Polyprotic Acid or Base 163

6G.6 Effect of Complexation on Solubility 165

6H Buffer Solutions 167

6H.1 Systematic Solution to Buffer

Problems 168

6H.2 Representing Buffer Solutions with

Ladder Diagrams 170

6I Activity Effects 171

6J Two Final Thoughts About Equilibrium

Chemistry 175

6K Key Terms 175

6L Summary 175

6M Suggested Experiments 176

6N Problems 176

6O Suggested Readings 178

6P References 178