A Workbook of. Electrochemistry

Transcription

1 A Workbook of Electrochemistry

2 A Workbook of Electrochemistry John O'M. Bockris Professor of Physical Chemistry The Flinders University Adelaide, Australia and Ronald A. Fredlein Lecturer in Physical Chemistry The University of Newcastle New South Wales, Australia PLENUM PRESS NEW YORK-LONDON 1973

3 Library of Congress Catalog Card Number ISBN-13: O e-isbn-13: DOl: / i Plenum Press, New York Softcover reprint of the hardcover 1st edition 1973 A Division of Plenum Publishing Corporation 227 West 17th Street, New York, N. Y United Kingdom edition published by Plenum Press, London A Division of Plenum Publishing Company, Ltd. Davis House (4th Floor) 8 Scrubs Lane, Harlesden, London NW 10 6 SE, England All rights reserved No part of this publication may be reproduced in any form without written permission from the publisher

4 PREFACE In this book, the objective has been to set down a number of questions, largely numerical problems, to help the student of electrochemical science. No collection of problems in electrochemistry has previously been published. The challenge which faces the authors of such a book is the breadth of the material in modern electrochemistry, and the diversity of backgrounds and needs of people who may find a "problems book" in electrochemistry to be of use. The general intention for Chapters 2-11 has been to give the first ten questions at a level which can be dealt with by students who are undergoing instruction in the science of electrochemistry, but have not yet reached graduate standard in it. The last two questions in Chapters 2-11 have been chosen at a more advanced standard, corresponding to that expected of someone with knowledge at the level of a Ph.D. degree in electrochemistry. Chapters I and 12 have a different character from the other chapters in the book. Chapter 1 is for the generalist who has some knowledge of the impending developments and rapid changes currently going on in electrochemistry, which results from the realization that we cannot continue with a fossil-fueled economy, and must turn increasingly to one which centers itself upon atomic energy and electricity. Chapter 12, on the other hand, presents a broad spectrum of problems in which no reservations have been made about the knowledge of the student. The questions in Chapter 12 should be answerable by an experienced graduate in electrochemical science -one who regards as his province the whole field, with its widespread applications. In Chapters 2-1 I, there has been a further breakdown of the problems. The first two or three problems are particularly simple and generally need only some direct application of one or two equations. v

5 vi PREFACE The presence of simple, direct questions of this character seems to be necessary to help the student obtain familiarity with the units, symbols, and basic ideas of the field. Any student who finds continued difficulties in obtaining satisfactory answers to Problems 1 and 2 of Chapters 2-11 is not sufficiently familiar with the basic concepts of modern electrochemistry and should undertake further course work or individual study before proceeding. A word must be said about the use of the book in courses of electrochemistry, electroanalytical chemistry, and electrochemical engineering. The book has been written predominantly for students in electrochemical science, i.e., that broad interdisciplinary field concerning the electrical properties of interfaces, and their contributions to the fields of metallurgy, energy conversion and storage, electrosynthesis, electrobiology, and so on. Students who wish to specialize in electroanalytical chemistry or electrochemical engineering have to go through a fundamental course in modern electrochemical science (which must of course be oriented in terms of quantum mechanics and solid state physics) as the foundation of their specialization. After such a fundamental course, they should be able to do at least Problems 1-\0 of Chapters The time needed to work out most of the problems in Chapters 2-11 varies from a few minutes each for Problems 1 and 2 (so long as the basic material is well understood beforehand and the relevant formula immediately recognized), to times of the order of one to two hours each for the Problems 3-10, to times of the order of a day for Problems 11 and 12. These latter problems are intended as "take-home exam" type problems, and the availability of libraries and computing machines is assumed. With respect to the necessary data, this has been given in Problems 1-10 of Chapters In Problems 11 and 12 of Chapters I- 11, and in all problems of Chapter 12, little or no information has been given, to simulate the actual conditions of problem-solving in the laboratory or office. Books of electrochemical constants are readily available and we may here mention the classic book by Latimer, Oxidation Potentials (2nd ed., 1952). Also, Electrochemical Data by Conway (1952) and the Handbook of Electrochemical Constants by Parsons (1959). Volumes 9a and 9b of Physical Chemistry by Eyring, Henderson, and Jost (1970) have many tables of constants, as do the books mentioned below. For a time, a great paucity of books on modern electrochemistry

6 PREFACE vii existed, but the field has had the benefit, in the last few years, of several new books. Of these must be mentioned Electrode Processes by B. E. Conway (1965), The Double Layer and Electrode Kinetics by P. Delahay (1967), Electrochemical Kinetics by K. Vetter (1967), Modern Electrochemistry by J. O'M. Bockris and A. K. N. Reddy (1970), the two volumes of electrochemistry in the Physical Chemistry volumes mentioned above, and Electrochemical Science by J. O'M. Bockris and D. Drazic (1972). Solutions have been provided to about half of the numerical problems of Chapters No attempts have been made to give solution to the problems of Chapter 12. Here, the discussion of a full answer might sometimes give rise to an original publication and the "correct" answer to some of the applied problems may be regarded as a matter of options and be subject to changing social and economic pressures. This book was written in the Electrochemistry Laboratory of the University of Pennsylvania. The authors acknowledge the assistance of many of their co-workers, especially: Dr. Bonciocat (Chapters 4 and 7), Dr. Buck (Chapter 6), Dr. McHardy (Chapters 9 and 10), Mr. O'Grady (Chapter ll), Dr. Paik (Chapters 2 and 3), and Mr. Sen (Chapters 5 and 8). Adelaide Newcastle August 1972 J. O'M. Bockris R. A. Fredlein

7 CONTENTS Preface General Questions about Electrochemistry 2. Ion-Solvent Interactions 3. Ion-Ion Interactions.. 4. Ion Transport in Solutions 5. Protons in Solution 6. Ionic Liquids 7. The Electrical Double Layer 8. Basic Electrode Kinetics.. 9. More Basic Electrode Kinetics 10. Some Electrodic Reactions of Interest 11. Some Aspects of Electrochemical Technology 12. Miscellaneous Problems v Appendices 1. Values of Some Important Physical Constants 2. Some Useful Conversion Factors ix