30 DOCUMENT 12 JUNE
1914
tion
von
I2
über
das als
einatomig angesehene
I2
so
ungeniert
übergelagert
ha-
ben.[6]
Aber
auf
mich wirkt die
Deduktion
trotzdem
überzeugend.
Haber
machte al-
lerdings geltend,
dass die
empfindlichen
Bezirke bei Atomen ein
Unding
seien,
vielleicht nicht
ganz
mit
Unrecht.[7]
Denn
die
Vorstellung,
dass das Atom ein
Ding
mit
bevorzugten Richtungen
sei,
befremdet. Aber ich
sage
mir
dass diese unnatür-
liche Konstruktion
jene
der Centralkräfte
paralysieren muss.
Es sieht nicht
so
aus,
als ob
man
bei
dieser
Behandlungsweise (Centralkräfte
+
empfindliche
Bezirke) zu
etwas
prinzipiell
falschem
gelangen
würde. Endlich denke ich
mir,
dass Habers Ar-
gument
das Wesentliche
aus
folgendem
Grunde nicht treffen wird. Um die Entro-
piedifferenz
beim
Nullpunkt
für
chemische
Verbindungen aus
der
Welt
zu
schaf-
fen,
muss man
räumliche
Ordnung
im Atomistischen
ausschliessen;
Zustände
räumlicher
Ordnung
von
verschiedenem
Grade in
makroskopischer Beziehung
(Konzentration!)
kann
man
aber
nicht
auschliessen. Deshalb wird dieses Aus-
kunftsmittel
überhaupt
nicht das
richtige
sein.
ALSX
(CBU,
Otto Stern
Papers
(85/96c)).
[71
119].
[1]Dated
by
the
reference
to
Stern,
O.
1914,
which
was published
4
June
1914.
[2]The paper
is
Stern, O.
1914.
[3]Ernst
Gehrcke (1878-1960)
was a
member of
the
Physikalisch-Technische
Reichsanstalt. A
year
earlier he had
published
an
attack
on relativity theory (Gehrcke 1913).
[4]Otto
Sackur
had been
Otto Stern’s
professor
at the
University
of
Breslau. As
a department
head
in Fritz Haber’s
Institute of
Physical Chemistry,
he
had
an
office in the
same building as
Einstein.
[5]In his
paper,
Stern derived
two
different
expressions
for the reaction rate
of
the chemical reaction
A+B
-
AB. The first followed from
a
calculation
based
on thermodynamics
and
using a quantum-
theoretical
expression
for
the
entropy
of
a
gas;
the
second derivation
was
based
on
Boltzmann’s
approach involving
kinetic
gas theory
and
molecular
forces
(see
Boltzmann
1898,
sec.
6).
The
com-
bination
of
the
two
results led
to
an expression
for
the
entropy change
associated
with
the reaction
in
terms
of
characteristic
parameters
of
the
intermolecular
(chemical)
forces. Comparison with
experi-
mental data
for
the
reaction
I2
-
2I seemed
to
indicate
that in this
case
the
entropy change
did not
vanish at absolute
zero, i.e.,
that Nernst’s
heat theorem
(which
states that at
absolute
zero
all
processes
are isentropic) was
not valid
for
this reaction.
At the
same
time,
Stern
explicitly
left
open
the
possi-
bility
of
an
alternative
explanation, pointing
out
that
there
were
also several
important
arguments
in
support
of
the
heat
theorem.
[6]Stern
found the
entropy
of
a system
of
diatomic molecules
by
calculating
the
entropy
of
mole-
cules with two
rotational
degrees
of
freedom and
simply adding
it to the
expression
for
the
entropy
of
molecules with
three
translational
degrees
of
freedom
(see Stern,
O.
1914,
p. 524).
[7]The
term “sensitive areas”
(“empfindliche
Bezirke”)
was
introduced
by
Ludwig
Boltzmann and
refers
to
his
assumption
that the attractive
(chemical)
forces between atoms
are only
active in certain
small
spaces
adjacent
to
specific parts
of
the surface
of
the
atoms.
In this
way
he could
account
for
the
valency
of
atoms.
Referring
to this
particular aspect
of
Boltzmann’s
theory,
Paul Ehrenfest had
asked Stern
what kind of
preestablished
harmony
Nernst’s heat theorem
imposed
on
the sensitive
areas
in Boltzmann’s
theory
of
gaseous dissociation,
thus
inspiring
Stern’s
investigation (see Stern,
O.
1914,
p.
497,
fn.
1).
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