An eye for an i #394 Children

The man who spotted the 'Tiger' in the lab

Portrait of Henri Moissan.

Portrait of Henri Moissan.   | Photo Credit: Nobel Lectures/ Wikimedia Commons

We now know a lot about fluorine. The lightest of the halogen elements with one single stable isotope, fluorine has an atomic number 9 and symbol F. It is one of the most reactive elements, capable of forming compounds even with some noble gases. And its ability to form stable and inert substances has enabled it to play a vital role in terms of medicinal and industrial usage.

Even though the existence of fluorine was well known for a long time, isolating it from its compound proved to be more than just tricky. So much so that it claimed the lives of a number of chemists in the 19th Century, including Belgian Paulin Louyet and Frenchman Jerome Nickles, who were attempting to become the first to isolate elemental fluorine from its many compounds.

The danger with fluorine

The problem lies in the fact that free fluoride ions bind well with calcium and magnesium in the body to form insoluble salts. These then precipitate and hinder proper functioning, leading to death of cells and corrosion of bones. This is why burns with hydrofluoric acid – a weak acid that can penetrate the skin and move rapidly towards deeper tissues – involving as small as 1/40th the body surface area could prove fatal.

It is for these reasons that Frenchman Henri Moissan’s success in isolating fluorine is celebrated. He not only had to handle hydrofluoric acid, which was the preferred compound in trying to isolate fluorine, but needed to have a way to take care of the fluorine itself, which is a violent and reactive gas.

Moissan attended the Museum of Natural History and the School of Pharmacy in Paris before going on to become professor of Toxicology (1886) and of Inorganic Chemistry (1889) at the School of Pharmacy and professor of Inorganic Chemistry (1900) at the Sorbonne.

A special apparatus

Moissan began working with fluorine compounds in 1884 and met with success on June 26, 1886. He achieved this by electrolysing a solution of potassium fluoride in hydrofluoric acid, preparing fluorine gas in the process.

An important factor that contributed to his success was an apparatus he constructed himself. He made this out of platinum – among the few metals capable of resisting an attack by fluorine – and cooled the electrolytic solution down to -50 degree Celsius in order to limit the corrosion. Moissan studied the fluorine he thus produced extensively, understanding its properties and its reaction with elements.

Uses aplenty

Since that day in 1886, the way we utilise fluorine has come a long way. Inorganic fluorides serve in cavity-fighting capacities in our toothpastes; fluorinated anaesthetics proved to be an alternative to existing options that were flammable or explosive; and radioactive fluorine is an important ingredient in positron emission tomography (PET) – an imaging technique to detect cancerous tumours at a much earlier stage.

With our ability to tinker with chemistry much more advanced in this day and age, fluorine has also been put to various industrial uses. As tetrafluoroethylene, better known as Teflon, fluorine has even entered our everyday lives, as the polymer remains a popular option in cookware.

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More about Moissan

Moissan received the 1906 Nobel Prize for Chemistry for the isolation of the element fluorine and also for the development of the Moissan electric furnace.

The Moissan electric furnace was a new type of furnace that used an electric arc as a source of heat. Using this furnace, Moissan was able to synthesise numerous new compounds and also vapourise substances that were regarded as infusible.

Moissan had over three hundred publications to his name, the most famous of which include Le Four Electrique (The electric-arc furnace in 1897), Le Fluor et ses Composes (Fluorine and its compounds in 1900) and Traite de Chimie Minerale (five volumes making up the Treatise on inorganic chemistry from 1904-1906).

Apart from being a patient experimentalist with an extraordinary eye for detail, Moissan was also an excellent lecturer.

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Printable version | Sep 27, 2020 6:30:24 PM | https://www.thehindu.com/children/the-man-who-spotted-the-tiger-in-the-lab/article31987379.ece

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