I think that Fritz Haber is a very interesting scientist with a fascinating life history. I first heard his story from an episode of RadioLab – which is a podcast I have recommended before. Haber was born in Germany in 1868 and went on to study chemistry at University in Berlin, completing his PhD under the supervision of the great Robert Bunsen (of Bunsen burner fame).
He won a Nobel Prize for his work “fixing nitrogen” from the atmosphere into ammonia. Nitrogen is a fairly unreactive and stable element so it is quite difficult to make ammonia under normal circumstances.
The reaction he helped to pioneer is called the Haber-Bosch process.
The secret to this seemingly simple reaction is a temperature of about 400°C, a high pressure roughly 200 times normal atmospheric pressure and a catalyst. The catalyst is mostly iron but with traces of silicon oxide, aluminium oxide, potassium oxide and calcium oxide. Ammonia is fantastically useful because it can be used to produce nitrogen fertiliser and explosives. The fertiliser produced by this process enabled Germany to feed its increasing population and the explosives allowed them to fight the First World War.
Plants use nitrate in the soil to make amino acids. These are the building blocks of protein. The availability of nitrate is therefore one of the main factors that affects the growth rate of plants. We would not be able to sustain the current human population without the increased yield made possible by artificial fertiliser. You can read a little more about such matters in my brief post on Norman Borlaug.
During the war, Fritz Haber worked loyally for the German government and developed a way to use chlorine gas as a weapon. When his wife (who was also a chemist) found out what he was planning she committed suicide but Haber went ahead and supervised the use of his new weapon himself. His attitude was that killing was killing and the means was irrelevant, although Germany had signed the 1907 Hague Convention outlawing the use of chemical weapons. Many saw Haber as a war criminal but he was decorated by the Kaiser and his Nobel Prize in 1918 was seen by many in the scientific community as highly controversial.
After the war he worked for a long time on a system for efficiently extracting gold from sea water. He was unsuccessful despite all of his efforts. You can read a little more about gold in this post from last Christmas. When the Nazis rose to power they recognised his ability and encouraged him to work on weapons for them despite the fact that Haber was Jewish. He saw how other Jewish scientists were being treated by the Nazis and in 1933 fled to Cambridge to escape the regime, but died in Switzerland just a year later. During WW2, the Germans took research Haber had done into manufacturing a cyanide based pesticide called Zyklon A and developed Zyklon B, which they used to gas prisoners in concentration camps. Cyanide is another nitrogen compound; hydrogen cyanide has the formula HCN, potassium cyanide KCN and so forth. It kills by obstructing the chemical pathways of cellular respiration.
This is only a very brief outline of one remarkable man’s life. I think he is a fascinating if slightly chilling figure. It is quite hard to weigh the good he did against the bad. Perhaps it only matters that he advanced our understanding of science and not how his research was used. What do you think?
Questions…
- What common name does each of the following have?
• silicon oxide
• aluminium oxide
• calcium oxide
- What pH would you expect if you dissolved potassium oxide in water?
- What are the chemical formulae of…
<
p style=”padding-left: 30px;”>• aluminium oxide
<
p style=”padding-left: 30px;”>• silicon oxide
• calcium oxide
• potassium oxide
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From the diagram above, what are the three processes that ensure a supply of nitrate in the soil?
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Chlorine is a halogen. Can you name any other halogens?
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