A Level Secondary Science

Fritz Haber’s Nobel Prize

In the autumn of 1918 the First World War was at last approaching an end. In neutral Sweden the committee for the Nobel Prize for Chemistry met.  As in 1916 and 1917 they decided that there had been no discovery that “conferred the greatest benefit on mankind” so did not make an award. A year later, however, they decided that the 1918 prize should be awarded to Fritz Haber, who was well known to have lead the research into the use of poison gases by the German army.  No one could think that this was of benefit to mankind so why was Haber awarded the prize, and why did he spend the last year of his life living in England?

The First World War was hugely destructive and many millions of soldiers, sailors and airmen were killed and wounded as well as many civilians. Science and engineering played a large part in the war.  Radio communications were developed and sonar was invented for detecting submarines.  New weapons, battleships, submarines, aircraft and tanks were designed. It was the first major war to use the high explosives that Alfred Nobel had invented, originally for peaceful purposes in mining. The war also saw the use of poison gases such as chlorine and mustard gas to kill and injure fighters. The war ended with Germany and its ally Austria-Hungary defeated, but with the victors, including Britain and France, exhausted.  For most of the war Germany had been blockaded by the British navy and was unable to import as many goods as in peacetime. One of the most important imports was nitrogen compounds. That was where Fritz Haber comes into the story.

Haber was born in 1868 in the town now known as Wroclaw in Poland. Then it was called Breslau and was part of the German state of Prussia.  Haber grew up a patriotic German and became interested in chemistry at an early age.  He had a successful career and in 1911 became Director of the Kaiser Wilhelm Institute of Physical Chemistry in Berlin. He did important research in several areas of chemistry but his most important work was on the process that carries his name for converting the nitrogen in the air into ammonia.

During the nineteenth century a rapid rise in population increased demand for food. It was realised that to grow more crops meant providing soil with fertiliser. There was not enough manure from farm animals so other sources were looked for.  On the coast of Chile in South America there were deposits of nitrates from bird droppings laid down over thousands of years. A huge trade developed in collecting the nitrates and carrying them by sea to Europe and the USA, but this resource would not last.

Other chemists had looked at methods of using the nitrogen in the air but it was Haber who in 1909 after years of experiments, made the crucial discovery. Using an iron catalyst at high temperature and pressure a reasonable amount of ammonia could be obtained from the reaction of nitrogen with hydrogen. Haber worked with Carl Bosch to turn the experimental reaction into an industrial process. The first factory opened in 1914. As well as needing fertiliser for its farms Germany also needed explosives for the war that began that year. The new explosives like nitro-glycerine, nitrocellulose and TNT all required nitric acid in their manufacture. With the Haber-Bosch process providing ammonia that could be converted to nitric acid, Germany was able to carry on manufacturing explosives even though their supplies of Chilean nitrate had been blockaded.

News of Haber’s process spread and its importance was recognised.  After the war ended in 1918, ammonia was soon being made using the process in many industrialised countries.  The production of artificial fertiliser was partly responsible for the “green revolution” that was able to feed the rapidly growing population during the twentieth century. Of course, it also enabled other products that require nitrogen, explosives and plastics such as nylon, to be manufactured.

Haber was a keen supporter of Germany at the outbreak of the war. He became a consultant to the German War Office and began research into the use of poisonous gases to help the German war effort.  He organised the first use of chlorine gas in April 1915 at Ypres in Belgium.  The gas destroys the linings of the lungs. If soldiers survived the attack they were often left with damaged lungs for life. The use of the gas depended on the weather and did not always achieve its purpose.  Nevertheless, following the first use by German forces it was used by both sides. Haber continued his research and developed other war gases such as phosgene and mustard gas. These gases were also put to use.  Soldiers became very afraid of gas attacks. Soldiers were not often killed immediately when the gases were released but treating the injured required large numbers of nurses and hospital beds. Many soldiers affected by gas spent months recovering in convalescent homes.  The care required to look after the wounded placed extra strain on the country’s economy.

Many people were against the use of poison gases in war. One of these was Haber’s wife Clara Immerwahr.  Clara was born in 1870 not far from Fritz Haber’s home.  She was also a trained chemist and the first woman to receive a doctorate at the University of Breslau. In 1901 she married Haber. She was unable to get a job as a chemist herself but assisted Haber in his research. Clara was a pacifist and was appalled when Haber began his work for the German War Office.  She tried to persuade him to stop the research but he refused.  On the evening before the first use of chlorine in 1915, she shot herself and died.

At the end of the war Haber was a German hero. His work had helped to feed the German population during the war, as well as providing the explosives that enabled the German armies to continue fighting.  His Nobel prize was awarded for the ammonia process which was recognised as of being a great benefit to mankind. There were protests that his war work was against the principles of the Nobel Prize but the Swedish committee ignored them.  Haber continued his research in Berlin including developing a pesticide called Zyklon B for use in agriculture. He also looked into ways of extracting gold from seawater to pay off the German debts from the war but that work came to nothing.

In 1933 the Nazis under Adolf Hitler took power in Germany.  One of their first moves was to remove Jews from organisations like the Kaiser Wilhelm Institute. Haber had been born to a Jewish family but had not been very religious.  In the 1890s he had converted to Christianity.  Clara was also a Christian from a Jewish family as was Haber’s second wife Charlotte (they married in 1917 and divorced in 1927). Haber was surprised and saddened by the actions of the Nazis. He found that he was no longer a German hero.  He tried to help other Jews working at the Institute to move out of Germany but had to give up his position.  He was invited to Cambridge University in England where he was welcomed by some scientists but not by others.  He was now unwell.  On his way to start a new job in Palestine (now Israel) early in 1934, he died in Basle, Switzerland. Some of his family who remained in Germany were taken to concentration camps where Zyklon B was used to kill many Jews.

Fritz Haber has remained a controversial figure.  His contributions to chemical knowledge and in particular development of a process which helped feed the world is set against his work to assist his country in a deadly war.


  • Why does farmland used to grow crops need to be fertilised?
  • Why was it so difficult to find a way of using nitrogen in the air to make ammonia and other compounds?
  • Fritz Haber discovered how to make nitrogen react with hydrogen to give a reasonable yield of ammonia.
    • What is the purpose of the iron used in the reaction?
    • Why is high pressure used in the process?
    • Why is high temperature used in the process?
    • Why is the industrial process more correctly called the Haber-Bosch process?
  • Do you think Haber’s work on making ammonia deserved a Nobel Prize? Give your reasons.
  • Why do you think Haber worked on war gases even though they had already been banned in 1907?
  • Describe the thoughts and feelings of Clara Immerwahr, Haber’s wife, in April 1915.
  • Haber may have given Germany a lead in the development of war gases but both sides used them in the First World War. Can the use of poison gas in war be justified? What are the advantages and disadvantages of poison gas compared to the use of high explosives in bullets, shells and bombs?
  • Was Fritz Haber a hero or villain, both or neither?
  • Describe Haber’s feelings in 1933 when the Nazis forced him out of his job.
  • If you had been at Cambridge University in 1933 what would you have felt when Haber arrived from Germany.


By Peter Ellis

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