Ammonium nitrate and iodine: a look back at the explosive history of two essential substances

The Conversation
From Barbara Demeneix


The horrific explosion that devastated Beirut on August 4, 2020, has receded, but the physical damage and human distress persists. Reports indicate that fireworks were also stored in the same warehouse as the fertiliser and could sparked the larger, more deadly explosion of the fertilizer.

The two faces of ammonium nitrate

Nitrogen makes up 78% of the atmosphere and is chemically and biologically inert. However, in 1908 the chemist Fritz Haber discovered that nitrogen could be fixed chemically as ammonium nitrate. As a German patriot, Haber was also interested in Germany’s preparation for what would become World War I. A problem was that the methods Haber used could not be scaled up for industrial production. It was a fellow German, Carl Bosch, who perfected the industrialisation of the method in 1913, a year before the war’s start.

Haber and Bosch were both awarded Nobel prizes for their work – Haber in 1918 and Bosch in 1931. The prizes were instituted by Alfred Nobel, who financed the prizes thanks to his patents for the explosives dynamite and gelignite. Like other explosives, these comprise a molecular mix that releases energy suddenly, most often accompanied by the production of heat, light, gases, pressure and deafening sound.

In his Nobel acceptance speech, Haber acknowledged only that his discovery would help feed the world by improving soil fertility with ammonia. And there is no doubt that it did – populations have more than tripled since then. However, the speech did not mention his the main motivation for his work, Germany’s war effort. Haber also contributed to that effort with the production of chlorine gas. What is more, Haber almost certainly did not anticipate the implications of his discovery for fixing ammonia for its contribution to climate change.

>> Lire la suite