Fritz Haber

Fritz Haber (born December 9, 1868, Breslau, Silesia, Prussia [now Wroclaw, Poland]—died January 29, 1934, Basel, Switzerland) was a German physical chemist and winner of the 1918 Nobel Prize for Chemistry for his successful work on nitrogen fixation. The Haber-Bosch process combined nitrogen and hydrogen to form ammonia in industrial quantities for production of fertilizer and munitions. Haber is also well known for his supervision of the German poison gas program during World War I.

Education and career

Born to a German Jewish family in Breslau, Haber received his early education at the local gymnasium. Influenced in part by his father’s occupation as a successful importer of natural dyes and pigments, he began his study of chemistry at the University of Berlin in 1886, but he transferred to Heidelberg after a single semester. After only a year and a half at Heidelberg, Haber’s university career was interrupted by a year of military service. He then transferred to the Charlottenburg Technische Hochschule in Berlin, where he worked under Karl Liebermann on the organic compound piperonal. Charlottenburg did not grant doctoral degrees, so he received his doctorate from the University of Berlin in 1891 for his work with Liebermann. Graduation was followed by three years of unrest, characterized by brief periods of industrial employment (including working for his father) interspersed with short bouts of postdoctoral study at the Technische Hochschule in Zürich and the University of Jena.

In 1894 Haber was appointed as an assistant in the Department of Chemical and Fuel Technology at the Fridericiana Technische Hochschule in Karlsruhe. Here he rapidly worked his way through the academic ranks to become a full professor in 1906. Haber remained at Karlsruhe until 1911, when he was called to head the newly founded Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry in the Berlin suburb of Dahlem. He directed the Institute until early 1933, when he resigned in protest over the newly enacted Nazi race laws. This was followed by four months of exile in England, where he worked in the laboratory of William Pope at the University of Cambridge. He died of a massive heart attack a few months later in Basel, Switzerland, while en route to Palestine to discuss the prospects for a position with the Daniel Sieff Research Institute, founded at Rehovot in 1934 by Chaim Weizmann, who became the first president of Israel in 1949.

Early research

Though originally trained as an organic chemist, Haber switched to the field of physical chemistry after his appointment at Karlsruhe. In keeping with the school’s engineering emphasis, his work became heavily oriented toward industrial applications. Indeed, this became the central theme of his entire research career—the elucidation and development of basic industrial processes through the application of rigorous theory. His initial work involved the physical chemistry of flames and combustion, which led to his first book, Experimental-Untersuchungen über Zerstetzung und Verbrennung von Kohlenwasserstoffen (1896; “Experimental Investigations on the Decomposition and Combustion of Hydrocarbons”). In addition to serving as a Habilitation thesis for his promotion to Privatdozent, this work would later prove valuable in elucidating the chemistry behind the refining and cracking of petroleum. Beginning about 1897, Haber added an interest in the theory and industrial applications of electrochemistry to his growing list of research themes. One result of his intensive efforts to master the literature in this field was his second book, Grundriss der technischen Elektrochemie auf theoretischer Grundlage (1898; “The Theoretical Basis of Technical Electrochemistry”). His contributions in this area include his studies of the electrochemical preparation of several important organic compounds such as nitrobenzene (1904), his study of the hydrogen-oxygen fuel cell (1907), and his pioneering work on the glass electrode (1909). Work on nitrobenzene led to a second book on electrochemistry, Die elektrolytischen Prozesse der organischen Chemie (1910; “The Electrolytic Processes of Organic Chemistry”), written in collaboration with German chemist Alexander Moser. Work on the glass electrode formed the basis for the later development of the pH meter, which measures hydrogen ion concentration, or acidity, in pH units as a function of electrical potential or voltage between suitable electrodes placed in the solution to be tested.

In 1904 Haber added yet a third research theme in the form of a growing interest in the thermodynamics of gas reactions. Here again his preliminary survey of the literature resulted in a book, Thermodynamik technischer Gasreaktionen (1905; The Thermodynamics of Technical Gas Reactions). His work in this area soon focused on the synthesis of ammonia gas from nitrogen and hydrogen gas and its potential as a method of nitrogen fixation. In 1898 the British chemist William Crookes warned that the world’s population would soon outstrip its food production unless crop yields were increased through the use of nitrogen fertilizers. Though the atmosphere is 78 percent nitrogen by volume, this nitrogen is unavailable to plants unless it is first “fixed” in the form of a water-soluble compound, such as ammonia or various nitrates. By 1908 Haber was able to show that the use of high pressures in combination with a suitable catalyst made ammonia synthesis practical, and the next year the process was turned over to the German chemist Carl Bosch at BASF Aktiengesellschaft for industrial development of what is now known as the Haber-Bosch process. In 1911 the first ammonia plant was built at Ludwigshafen-Oppau, which produced over 30 tons of fixed nitrogen per day by 1913. In 1918 Haber was awarded the Nobel Prize for Chemistry for his role in ammonia synthesis, and in 1931 Bosch belatedly received a Nobel Prize for his contributions as well.

Chemical warfare

With the coming of World War I, Haber wholeheartedly devoted the resources of his research institute to meeting Germany’s wartime demands for chemical products and synthetic substitutes. Most of his published work during this period concerned the refinement of ammonia synthesis. When coupled with German chemist Wilhelm Ostwald’s process for the oxidation of ammonia to nitric acid, the combined process held the key not only to fertilizer and food production but also to the synthesis of nitrates and other explosives essential to modern warfare. Requests from the military for possible tear gases and other irritants led Haber to propose the use of chlorine gas as a chemical weapon, a suggestion first tried at Ypres, France, in April 1915. The use of gas-warfare agents rapidly increased on both sides of the conflict, and by 1916 Haber found himself acting as chief of Germany’s Chemical Warfare Service. After the war, Haber was severely criticized and in some cases even ostracized for his involvement in the gas-warfare program. As for his role in ammonia synthesis, it was argued that the cutting off of Germany’s access to natural nitrate deposits in northern Chile by the British Royal Navy would have ended the war within a few months had not the ammonia process given Germany the ability to make its own nitrates and explosives. These criticisms overlooked the positive role of the synthesis in fertilizer production and the fact that British, French, and American chemists were more than willing to develop poison-gas agents and explosives for their own governments.

Postwar years

In the postwar years, Haber’s increasing administrative responsibilities, combined with his involvement in several international scientific organizations and his fame as a Nobel Prize winner, led to a decline in his output of purely technical papers and to a simultaneous increase in his output of popular articles and lectures. Many of these were collected in two volumes, Fünf Vorträge aus den Jahren 1920–1923 (1924; “Five Lectures from the Years 1920–1923”) and Aus Leben und Beruf: Aufsätze, Reden, Vorträge (1927; “From Life and Work: Essays, Speeches, Lectures”). Technical projects of interest during this period include his unsuccessful experiments (1920–26) in extracting gold from seawater in order to pay Germany’s war debt and his proposal (1919) of a simple graphical method for calculating the energies of ionic crystals. Universally known as the Born-Haber cycle, this procedure is discussed in most inorganic chemistry and in many general chemistry textbooks.

Personal life

Not only was Haber’s public life steeped in controversy, his private life was touched with tragedy as well. His mother, Paula, died from complications from his birth, and there is evidence that this resulted in a lifelong strain between Haber and his father. Haber’s first wife, Clara Immerwahr, committed suicide in 1915, ostensibly in protest of Haber’s involvement in the gas-warfare program, and his second marriage to Charlotta Nathan ended in divorce in 1927. Haber had a son (Hermann) by his first wife and both a daughter (Eva) and son (Ludwig) by his second wife. Ludwig Haber became a well-known economist and historian of industrial chemistry. In 1986 he published The Poisonous Cloud, a definitive history of the use of gas warfare during World War I.