Analytical Chemistry

Transcription

1 Applications of Microsoft Excel in Analytical Chemistry Second Edition / Stanley R Crouch Michigan State University F James Holler University of Kentucky - > BROOKS/COLE 1* CENGAGE Learning- Australia Brazil Japan Singapore Korea Mexico Spain United Kingdom United States

2 CONTENTS CHAPTER 1 Excel Basics 1 Getting Started 2 Calculating a Molar Mass 4 Entering Text and Data in the Worksheet 4 Entering an Equation 5 Documenting the Worksheet 7 Laboratory Notebook Example 8 Changing the Width ofa Column 10 Entering Numbers into the Spreadsheet 10 Filling Cells Using the Fill Handle 11 Making Complex Calculations with Excel 13 An Example from Gravimetric Analysis 14 More Cell Formatting 14 Entering the Data 15 i Calculating Molar Masses 16 Calculating the Percentages 16 Documenting the Spreadsheet 17 Importing and Using Molar Mass Data 19 Importing Data from Web Pages 19 Dealing with Character Strings 21 Making the Calculation 29 Summary 31 Problems 31 CHAPTER 2 Basic Statistical Analysis with Excel 34 Calculating a Mean with Excel 34 Finding the Mean 35 Using Excel's Built-in Functions 36 Finding the Deviations from the Mean 37 Editing Formulas 38 Computing the Standard Deviation 39 Finding the Variance 39 A Shortcut for Perfprming a Summation 40 Finding the Standard Deviation 42 The Built-in Statistical Functions of Excel 43 The Coefficient of Variation, or Percent Relative Standard Deviation 44 Standard Error of the Mean 45 Computing Descriptive Statistics with the Analysis TpolPak 47 The Analysis ToolPak Calculating the Pooled Standard Deviation 49 Finding the Sum ofthe Squares ' 47 ofthe Deviations 50 Finding the Total Sum of Squares 52 Confidence Intervals 54 Confidence Intervals when a is Known 54 Confidence Intervals when s Must Be Used 57 Summary 59 Problems 60 iii 2014 Cengage Learning All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part

3 Finding CHAPTER 3 Statistical Tests with Excel 64 t Tests 64 Comparing Means Assuming Equal Variances 64 Manual Calculation 65 Using the Excel Built-in Functions 68 Paired Two-Sample t Test 70 F Test for Comparison of Variances 74 ANOVA 77 Entering ANOVA Formulas-Manually 77 The Analysis ToolPak ANOVA Tool 81 Distribution-Free Methods 83 Wilcoxon Signed-Rank Test for Single Samples 84 Wilcoxon Signed-Rank Test for Paired Data 87 Summary 88 Problems 89 ' CHAPTER 4 Least-Squares and Calibration Methods 95 Linear Least-Squares Analysis 95 The Slope and Intercept 96 Using LINEST 99 The Analysis ToolPak Regression Tool 100 Plotting a Graph of the Data and the Least-Squares Fit 102 Using Excel to Find Unknown Concentrations from a Calibration Curve 105 The Internal Standard Method 109 Method of Standard Additions 111 Principles of Multiple Standard Additions 111 the Unknown Concentration 113 Analyzing Errors 113 the Curve 115 Plotting, Multiple Linear Regression '115 LINEST 116 Analysis ToolPak 117 Linear Regression with Polynomials 118 Summary 122 Problems 123 CHAPTER 5 Equilibrium, Activity and Solving Equations 132 A Quadratic Equation Solver 132 Using Excel to Iterate 134 Using Excel's Solver 136 Solving a Cubic Equation 141 Solving a Quartic Equation 143 Exploring the Ionic Strength Dilemma 143 An Iterative Solution 144 Using Solver to Obtain the Solution Directly 148 Summary 151 Problems 151 iv 2014 Cengage Learning All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in plait

4 ' CHAPTER 6 The Systematic Approach to Equilibria: Solving Many Equations 155 Using Solver for Complex Equilibrium Problems 156 Finding the Concentrations Simultaneously with Solver 156 Goal Seek Finding A Single Concentration with Solyer 158 ' 160 What is Goal Seek and How Does it Work? 160 Finding the Solubility of Mg(OH)2 with Goal Seek 160 Solving Simultaneous Linear Equations 163 Method ofdeterminants 164 Matrix Operations 167 Systems with Large Numbers ofequations and Unknowns 169 Some Additional Examples of Equilibrium Problems 170 v Solubility at a Fixed ph 170 Solubility When the ph is Unknown 173 Summary 175 Problems 176 CHAPTER 7 Neutralization Titrations and Graphical Representations 179 Calculating and Plotting a Strong Acid/Strong Base Titration Curve 179 Stoichiometric Method 179 Using the Charge-Balance Equation 186 Weak Acid-Strong Base Titrations 188 Stoichiometric Method 189 Master, Equation Approach 193 Distribution of Species: a Plots 197 Derivative Plots 199 First Derivative Plot 200 Second Derivative Plot 203 Producing a Combination Plot 206 Gran Plots 208 Summary 210 Problems 211 CHAPTER 8 Polyfunctional Acids and Bases 214 > - Distribution Diagrams 214 A General Expression for a Values 214 Diprotic Acid System 215 What About Bases? 217 Logarithmic Concentration Diagrams 218 Estimating Concentrations at a Given ph Value 221 Finding ph Values 221 Titration Curves for Weak Acids 223 Stoichiometric Method 223 Alpha Values During a Titration 230 An Inverse Master Equation Approach 232 Titration Curves for Difunctional Bases 237 Amphiprotic Species, Amino Acids, and the Isoelectric Point 239 Summary 242 Problems 243 v 2014 Cengage Learning All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part

5 CHAPTER 9 Complexometric and Precipitation Titrations Complexation Equilibria a-values for Complexes Inverse Master Equations for Complexometric Titrations Ligands that Protonate Complexation Reactions with Protonating Ligands Conditional Formation Constants EDTA: A Ubiquitous Ligand EDTA as a Tetraprotic Acid Titrating EDTA with Base Titrating Metals with EDTA Stoichiometric Approach Inverse Master Equation Approach Precipitation Titrations Summary Problems Stoichiometric Method Direct Master Equation Approach Calculation of Volumes Needed to Produce agivenpag CHAPTER 10 Potentiometry and Redox Titrations 282 Calculating Electrode Potentials 282 Cell Potentials and Equilibrium Constants 284 a-values for Redox Species 285 Redox Titrations 289 Stoichiometric Method 289 Inverse Master Equation Approach 291 Calculating System Potentials from the Master Equation 293 A More Complex Titration Example '294 Summary 296 Problems 297 CHAPTER 11 Dynamic Electrochemistry 300 Controlled-Potential Coulometry 300 Basic Principles 300 Numerical Integration 301 Coulometric Titrations 306 Voltammetry 310 Voltammetric Determination 310 Determination ofhalf-wave Potentials 311 Determination offormation Constant and Formula of a Complex 313 Amperometric Titrations 314 Summary 318 Problems 320 vi 2014 Cengage Learning All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part

6 CHAPTER 12 Spectrochemical Methods 325 Beer's Law 325 Absorptivity 326 Deviations from Beer's Law 327 Precision ofabsorption Measurements 333 Calibration Methods 336 External Standard Methods 336 Adding Error Bars to a Chart 338 Standard Additions Methods 340 Weighted Linear Regression 341 Multicomponent Methods 347 Iteration 348 Method of Determinants 350 Matrix Methods 352 Spectrophotometric Titrations 352 Spectrophotometric Study of Complex Ions 356 Method of Continuous Variations 357 Producing Charts with Insets 358 Summary 359 Problems 360 CHAPTER 13 Kinetic Methods 368 Rate Laws for Simple Reactions 368 Comparing First- and Second-Order Reactions 368 Determining Reaction Orders 371 Pseudo First-Order Systems 374 Enzyme-Catalyzed Reaction 379 Linear Transformation 379 Nonlinear Regression Approach 382 Kinetic Methods of Analysis 385 Summary 389 Problems 390 CHAPTER 14 Chromatography 394 Chromatographic Terminology and Basic Equations 394 Simulating a Chromatogram 397 Finding the Number ofplates to Achieve a Given Resolution 400 Nonideal Peak Shapes 401 Optimizing Chromatographic Methods: van Deemter N Equation 404 Van Deemter Plots 404 Using Solver to Find van Deemter Coefficients 406 Quantitative Chromatography 409 Method of External Standards 410 Internal Standard Method 411 Summary 413 Problems 415 r vii 2014 Cengage Learning All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part

7 CHAPTER 15 Electrophoresis and Other Separation Methods 419 Resolution of Overlapped Gaussian Peaks 419 Electrophoresis 423 Determining Mobilities of Inorganic Ions 424 Determining the pka Values ofweak Acids 427 Micellar Electrbkinetic Capillary Chromatography 430 Summary 433 Problems 434 CHAPTER 16 Data Processing with Excel 436 Smoothing Generating Noise 437 Moving Average Smoothing 439 Exponential Moving Averages 442 Savitzky-Golay Smoothing 444, Feature Removal and Enhancement 446 of Data 436 Feature Removal 447 Feature Enhancement 449 Recursive Estimation Methods 453 Summary 458 Problems V 459 viii Cengage Learning All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part