published a truly remarkable book, Thermodynamik Technischer
Gasreactionen, (The Thermodynamics of Technical Gas Reactions).
34
According to J. E. Coates,
1 this book holds an important place in the history
of chemical thermodynamics and for three reasons viz., ‘its influence on
teaching, its attack on the problem [of entropy change at absolute zero] that
Nernst solved a year later, and its timely provision of the first systematic
critical survey of all the thermodynamic data necessary for the calculation of
the free energy changes in the most important gas reactions’—all of which we
come to shortly. But important as this book was, it was not the seminal
moment of Haber’s life. That occurred about one year earlier—although
Haber would never have recognised it. This moment occurred somewhere
around 1903/4. Haber received an unexpected request from the Margulies
brothers of the Osterreichische Chemische Werk in Vienna. They had
detected small but noticeable traces of ammonia in their chemical plant and
they wondered if they had somehow stumbled upon a viable method of
making this valuable chemical feedstock. Otto and Robert Margulies asked if
there would be any chance of finding a metal which could be used for the
continuous production of ammonia by passing a mixture of nitrogen and
hydrogen over it, making firstly the nitride then reducing the nitride with
hydrogen to form ammonia, the solid metal phase acting as catalyst.
There had already been many attempts to promote a reaction between
these two gases (Chap. 3) none of which had succeeded and a widely held
belief arose that it was probably impossible to achieve such an elemental
synthesis. As a result, Haber was noticeably uninterested in this opportunity
and indeed wrote to Wilhelm Ostwald offering him the work. Haber was
aware that Ostwald had studied the problem some years earlier and thought
that he had taken it as far as it was technically feasible. But puzzled by
Ostwald’s disinterest in the matter and persuaded by the brothers persistence
35 and their generous financial offer, he and his young student Gabriel
van Oordt spent some time in the summer of 1904 investigating the process
suggested by the brothers. Preliminary experiments on the reduction and
regeneration of calcium and magnesium nitrides indicated little hope in the
use of these metals due to the high temperatures required. Haber then
decided to examine the thermal synthesis of ammonia from its elements using
(unsurprisingly) iron as a catalyst. Although this was not part of the original
brief, his clear understanding was that whatever the pathway to ammonia
production, the yield was governed by the position of the ammonia equilibrium in what was possibly a reversible process;
2 Fritz Haber and Karlsruhe
55
Gasreactionen, (The Thermodynamics of Technical Gas Reactions).
34
According to J. E. Coates,
1 this book holds an important place in the history
of chemical thermodynamics and for three reasons viz., ‘its influence on
teaching, its attack on the problem [of entropy change at absolute zero] that
Nernst solved a year later, and its timely provision of the first systematic
critical survey of all the thermodynamic data necessary for the calculation of
the free energy changes in the most important gas reactions’—all of which we
come to shortly. But important as this book was, it was not the seminal
moment of Haber’s life. That occurred about one year earlier—although
Haber would never have recognised it. This moment occurred somewhere
around 1903/4. Haber received an unexpected request from the Margulies
brothers of the Osterreichische Chemische Werk in Vienna. They had
detected small but noticeable traces of ammonia in their chemical plant and
they wondered if they had somehow stumbled upon a viable method of
making this valuable chemical feedstock. Otto and Robert Margulies asked if
there would be any chance of finding a metal which could be used for the
continuous production of ammonia by passing a mixture of nitrogen and
hydrogen over it, making firstly the nitride then reducing the nitride with
hydrogen to form ammonia, the solid metal phase acting as catalyst.
There had already been many attempts to promote a reaction between
these two gases (Chap. 3) none of which had succeeded and a widely held
belief arose that it was probably impossible to achieve such an elemental
synthesis. As a result, Haber was noticeably uninterested in this opportunity
and indeed wrote to Wilhelm Ostwald offering him the work. Haber was
aware that Ostwald had studied the problem some years earlier and thought
that he had taken it as far as it was technically feasible. But puzzled by
Ostwald’s disinterest in the matter and persuaded by the brothers persistence
35 and their generous financial offer, he and his young student Gabriel
van Oordt spent some time in the summer of 1904 investigating the process
suggested by the brothers. Preliminary experiments on the reduction and
regeneration of calcium and magnesium nitrides indicated little hope in the
use of these metals due to the high temperatures required. Haber then
decided to examine the thermal synthesis of ammonia from its elements using
(unsurprisingly) iron as a catalyst. Although this was not part of the original
brief, his clear understanding was that whatever the pathway to ammonia
production, the yield was governed by the position of the ammonia equilibrium in what was possibly a reversible process;
2 Fritz Haber and Karlsruhe
55