Electrochemical Methods of Analysis Thomas Wenzel Department of Chemistry Bates College, Lewiston ME 04240
[email protected] The following textual material is designed to accompany a series of in-class problem sets that develop many of the fundamental aspects of electrochemical analytical methods. TABLE OF CONTENTS 1. Basic Concepts in Electrochemistry 2 2. The Chemical Energy of a System 4 3. Relationship of Chemical Energy to Electrochemical Potential 10 4. Table of Standard State Electrochemical Potentials 12 5. Electrochemical Cells 14 6. Potential of an Electrochemical Cell 20 7. Electrochemical Analytical Methods 24 7.1. Ion-Selective Electrodes 25 7.1.1. pH Electrode 25 7.1.2. Other Glass Electrodes 27 7.1.3. Membrane Electrodes 27 7.1.4. Enzyme Electrodes 28 7.1.5. Solid-State Electrodes 28 7.1.6. Gas-Sensing Electrodes 28 7.2. Electrodeposition/Electrogravimetry 29 7.3. Coulometry 31 7.4. Titrimetric Methods of Analysis 33 7.4.1. “Classical” Redox Titration 33 7.4.2. Coulometric Titration (Controlled Current Coulometry) 33 7.4.3. Amperometric Titration 35 7.4.4. Potentiometric Titration 37 7.5. Voltammetric Methods 44 7.5.1. Anodic Stripping Voltammetry 46 7.5.2. Linear Sweep Voltammetry 49 7.5.3. Differential Pulse Linear Sweep Voltammetry 52 7.5.4. Cyclic Voltammetry 55 1 1. Basic Concepts in Electrochemistry Electrochemical processes are commonly used for analytical measurements. There are a variety of electrochemical methods with different degrees of utility for quantitative and qualitative analysis that are included in this unit. The coverage herein is not exhaustive and methods that are most important or demonstrate different aspects of electrochemical measurements are included.