Table Of ContentContributors
BARBARA J. BARKER
E. C. BAUGHAN
JOSEPH A. CARUSO
W. H. LEE
ANN T. LEMLEY
JUKKA MARTINMAA
JOHN H. ROBERTS
MICHEL RUMEAU
THE CHEMISTRY OF
NONAQUEOUS SOLVENTS
Edited by J. J. LAGOWSKI
DEPARTMENT OF CHEMISTRY
THE UNIVERSITY OF TEXAS AT AUSTIN
AUSTIN, TEXAS
Volume IV
SOLUTION PHENOMENA AND APROTIC SOLVENTS
1976
ACADEMIC PRESS New York San Francisco London
A Subsidiary of Harcourt Brace Jovanovich, Publishers
COPYRIGHT © 1976, BY ACADEMIC PRESS, INC.
ALL RIGHTS RESERVED.
NO PART OF THIS PUBLICATION MAY BE REPRODUCED OR
TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC
OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY
INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT
PERMISSION IN WRITING FROM THE PUBLISHER.
ACADEMIC PRESS, INC.
Ill Fifth Avenue, New York, New York 10003
United Kingdom Edition published by
ACADEMIC PRESS, INC. (LONDON) LTD.
24/28 Oval Road, London NW1
Library of Congress Cataloging in Publication Data
Lagowski, J J ed.
The chemistry of non-aqueous solvents.
Includes bibliographies.
CONTENTS.-v. 1. Principles and techniques.-v. 2.
Acidic and basic solvents.-v. 3. Inert, aprotic, and
acidic solvents.—v. 4. Solution phenomena and aprotic
solvents.
1. Nonaqueous solvents. I. Title.
TP247.5.L3 660.2V482 66-16441
ISBN 0-12-433804-6
PRINTED IN THE UNITED STATES OF AMERICA
List oi Contributors
Numbers in parentheses indicate the pages on which the authors' contributions begin.
BARBARA J. BARKER, Department of Chemistry, Hope College, Holland,
Michigan (109)
E. C. BAUGHAN, Department of Chemistry and Metallurgy, Royal Military
College of Science, Shrivenham, near Swindon, Wilts., England (129)
JOSEPH A. CARUSO, Department of Chemistry, University of Cincinnati,
Cincinnati, Ohio (109)
W. H. LEE, Department of Chemistry, University of Surrey, Guildford,
Surrey, England (167)
ANN T. LEMLEY,* Department of Chemistry, Cornell University, Ithaca,
New York (19)
JUKKA MARTINMAA, Department of Wood and Polymer Chemistry,
University of Helsinki, Helsinki, Finland (247)
JOHN H. ROBERTS, Department of Chemistry, The University of Texas,
Austin, Texas (1)
MICHEL RUMEAU, Faculte des Sciences et des Techniques, Centre Uni-
versitaire de Savoie, Chambery, France (75)
* Present address: Department of Applied and Engineering Physics, Cornell University,
Ithaca. New York.
IX
Preface
The contributions to Volume IV of this treatise complement different
parts of the first three volumes. The first three chapters—Conductivity in
Nonaqueous Solvents; Hydrogen Bonding Phenomena; and Redox Systems
in Nonaqueous Solvents—are a continuation of the themes developed in
Volume I in which the discussion of phenomena or techniques stands apart
from the nature of the solvent although solvent effects are important and are
discussed. The remaining chapters are critical reviews of specific aprotic
solvents and, hence, can be considered as an extension of a part of Volume III,
e.g., aprotic solvents.
The cooperation of the staff of Academic Press in many diverse areas is
gratefully acknowledged as is the effort expended by the authors in meeting
the necessary deadlines. I should also like to acknowledge the help of
Ms. R. Schall who assisted in numerous ways in the preparation of this
volume.
J. J. LAGOWSKI
XI
Contents of Previous Volumes
VOLUME I PRINCIPLES AND TECHNIQUES
Lewis Acid-Base Interactions in Polar Non-aqueous Solvents
DEVON W. MEEK
Solvation of Electrolytes and Solution Equilibria
ELTON PRICE
Acidity Function for Amphiprotic Media
ROGER G. BATES
Electrode Potentials in Non-aqueous Solvents
H. STREHLOW
Solvent Extraction of Inorganic Species
LEONARD I. KATZIN
Experimental Techniques for Low-Boiling Solvents
JINDRICH NASSLER
Experimental Techniques in the Study of Fused Salts
R. A. BAILEY and G. J. JANZ
Author Index—Subject Index
VOLUME II ACIDIC AND BASIC SOLVENTS
Liquid Hydrogen Chloride, Hydrogen Bromide, and Hydrogen Iodide
FRANK KLANBERG
Anhydrous Hydrogen Flouride as a Solvent and a Medium for Chemical Reactions
MARTIN KILPARTICK and JOHN G. JONES
Sulfuric Acid
W. H. LEE
xiii
XIV CONTENTS OF PREVIOUS VOLUMES
Nitric Acid
W. H. LEE
Amides
JOE W. VAUGHN
The Physical Properties of Metal Solutions in Non-aqueous Solvents
J. C. THOMPSON
Liquid Ammonia
j. j. LAGOWSKI and G. A. MOCZYGEMBA
Author Index—Subject Index
VOLUME III INERT, APROTIC, AND ACIDIC SOLVENTS
Bronsted Acid-Base Behavior in "Inert" Organic Solvents
MARION MACLEAN DAVIS
Liquid Sulfur Dioxide
D. F. BUROW
Acyl Halides as Nonaqueous Solvents
RAM CHAND PAUL and SARJIT SINGH SANDHU
Liquid Hydrogen Sulfide
F. FEHER
Anhydrous Acetic Acid as Nonaqueous Solvent
ALEXANDER I. POPOV
Other Carboxylic Acids
ALEXANDER I. POPOV
Author Index—Subject Index
Conductivity in Nonaqueous Solvents
JOHN H. ROBERTS
Department of Chemistry
The University of Texas, Austin, Texas
L Introduction . . . . . . .. 1
II. Theory of Electrical Conductivity . . .. 2
A. Definition of Terms . . . . .. 2
B. Fundamental Conductivity Equation 3
C. Factors Affecting the Mobility of Ions 3
D. Conductivity E q u a t i o n s . . . . .. 5
E. Which Conductivity Equation to Use? 8
III. Experimental Techniques . . . . .. 10
A. Measurement of Electrolytic Conductivity 11
B. Conductivity Cells . . . . .. 11'
C. Auxiliary Apparatus . . . . .. . 12
IV. Recent Research in Nonaqueous Solvents 13
References . . . . . . .. 16
I. INTRODUCTION
Interest in the nature of electrolytic solutions has been of great importance
historically in the development of presently held concepts of the nature of
ionic compounds and their physical chemistry and electrochemistry. Obser
vation, understanding, and description of electrolytic conductivity were
particularly significant for the early development of solution theory and today
electrolytic conductivity remains one of the primary investigatory tools for
1
2 JOHN H. ROBERTS
the study of electrolytic solutions. Numerous experimental techniques have
been developed to determine the mobilities of ions in solution and the fraction
free to conduct. This in turn allows calculation of thermodynamic quantities
such as association constants.
Parallel development of the theory of conductivity has resulted in a hydro-
dynamic model for solutions which is widely used and accepted in many
fields of science. The ease of mathematical calculation brought about by the
development of large computers has allowed an increasingly better fit of
precise experimental data to theoretical expectations. The latest forms of the
most widely used conductivity equations now contain many higher terms.
New developments appear in the literature frequently and on many points
of interest there is still controversy.
Conductometric studies have also been of great importance in elucidating
the nature of phenomena in nonaqueous solvents. Unanticipated behavior,
in terms of what one would expect for aqueous solutions, is more often the
rule than the exception. After discussing the theory of conductivity and ele
mentary experimental considerations some of the interesting recent research
in nonaqueous solvents will be discussed.
II. THEORY OF ELECTRICAL CONDUCTIVITY
A. Definition of Terms
According to Ohm's Law the current /, in amperes, flowing through a
conductor is proportional to the electromotive force E, in volts, and is inversely
proportional to the resistance of the conductor R, in ohms.
E
i = -R (i)
The resistance R depends on the quantity and shap2e of the material. For a
material of uniform cross section and of area a cm and length / cm we have
E rl
R = - = - (2)
I a
where r is the specific resistance. The specific conductivity L is defined as the
reciprocal of r.
K J V
L = — (3)
R
The cell constant K depends on the size, shape, and surface of the electrodes
of the conductivity cell and on the distance between them.
For a solution of an electrolyte the specific conductivity depends on the
1. CONDUCTIVITY 3
ions present, and therefore it is useful to consider the conductivity per unit of
concentration A, the equivalent conductivity
3
10 L
A =— (4)
where C is the concentration in gram equivalents per liter.
B. Fundamental Conductivity Equation
The equivalent conductivity is proportional to the current which is carried
through the solution in the conductivity cell. Since the current is carried only
by the ions of the dissolved electrolyte it is also necessary to consider factors
which affect ion transport. Thus,
A = (current carried by positive ions) + (current carried by negative ions)
(5)
Since Faraday's law states that one gram equivalent weight of a substance is
discharged at each electrode by 96,487 (IF) coulombs of electricity passed
through an electrolytic solution and current is defined as coulombs per
seconds, Eq. 5 may be stated in terms of equivalents as
++
A = ^cm + 3Fc~m~ (6)
+
where c and c~~ are the numbers of posi+tive and negative ions per equivalent
of solute in the conductivity cell and m and m~ +are the mobilities of the
respective ions. For a 1:1 electrolyte in solution c = c~ = a, the number
of equivalents of either ion per equivalent of solute, and so
r +
A = &a(m +m~) (7)
This fundamental conductivity equation is a concise statement of the source
of conductivity of electrolytic solutions, namely, that the conductivity is a
function of the number of ions and their mobilities. Considerations of the
factors which affect these two variables have led to the development of a
number of conductivity equations which will subsequently be discussed.
C. Factors Affecting the Mobility of Ions
In an infinitely dilute solution the ions are far apart so the only hindrance
to their motion toward the electrodes is the friction of their passage through
the solvent. Consequently the mobilities should remain constant, and
± ±0
m = m
±0
where m is the mobility of the ion at infinite dilution.
