CHAPTER 10 ELECTROLYTE SOLUTIONS
10.4 THEDEBYE–HUCKEL ̈ THEORY 295
BIOGRAPHICAL SKETCH
Peter Josephus Wilhelmus Debye (1884–1966)Peter Debye made major contributions to vari-
ous areas of chemistry and physics.
He was born in Maastricht, The Nether-
lands, where his father was foreman in a ma-
chine workshop.
Henri Sack, a close associate for 40 years,
recalled in 1968:a
He was not only endowed with a most powerful
and penetrating intellect and an unmatched abil-
ity for presenting his ideas in a most lucid way,
but he also knew the art of living a full life. He
greatly enjoyed his scientific endeavors, he had
a deep love for his family and home life, and he
had an eye for the beauties of nature and a taste
for the pleasure of the out-of-doors as manifested
by his hobbies such as fishing, collecting cacti,
and gardening, mostly in the company of Mrs.
Debye.
Before World War II, Debye held appoint-
ments at several universities in The Nether-
lands, Switzerland, and Germany. He emi-
grated to America in 1940 and was at Cornell
University in Ithaca, New York until his death.
He became an American citizen in 1946.
Debye was responsible for theoretical treat-
ments of a variety of subjects, including
molecular dipole moments (for which thede-
byeis a non-SI unit), X-ray diffraction and
scattering, and light scattering. His theories
relevant to thermodynamics include the tem-
perature dependence of the heat capacity of
crystals at a low temperature (Debye crys-
tal theory), adiabatic demagnetization, and the
Debye–Huckel theory of electrolyte solutions. ̈
In an interview in 1962, Debye said that heactually had not been interested in electrolytes
at all. He had been at a colloquium at which a
new theory of electrolytes had been described
that was supposed to explain why the conduc-
tivity of a dilute solution of a strong electrolyte
is proportional to the square root of the con-
centration. Debye, on hearing this description,
objected that the theory neglected the effects
of Brownian motion. The discussion became
heated, and some of those present told Debye
“you will have to do something about it.” What
Debye did about it was to ask his assistant,
Erich Huckel, to study the literature and find ̈
out what they were missing. That, according
to Debye in the interview, is how the Debye–
Huckel theory came about. ̈ b
In a reminiscence of Debye published in
1972, Erich Huckel wrote: ̈ c
My personal relations with Debye were always
completely care-free. Although I was 12 years
younger than he and a complete freshman when
I came to Zurich, he always treated me as his ̈
equal.... Debye conceived his work—in my
opinion—as an artist who operates on the ba-
sis of joy in his work and its creations, and who
was led often by intuition, which was then later
on rationally founded in the most plain and clear
way leaving out everything that was unessential.
... I never found in Debye any interest in philo-
sophical questions. Debye’s way of life seemed
to me rather straightforward and uncomplicated.
He liked a good dinner: when a problem could
not be solved after a physics lecture, he used to
say: “one must enjoy a good evening dinner and
then the inspiration comes by itself”... Debye
received an immense number of awards. It did
not seem to matter much to him. When I vis-
ited him in Berlin to congratulate him on the
Nobel Prize, he interrupted: “Fine that you are
here.” My congratulations were therefore not
completed.
Debye was awarded the 1936 Nobel Prize in
Chemistry “for his contributions to our knowl-
edge of molecular structure through his in-
vestigations on dipole moments and on the
diffraction of X-rays and electrons in gases.”
aRef. [ 57 ], page 232. bRef. [ 43 ]. cTranslation in Ref. [ 161 ], pages 73–74.