- Person
- Henri Moissan
- Lived
- 1852–1907
- Field
- Inorganic chemistry
- From
- French
The story
By the nineteenth century chemists were sure that the mineral fluorspar and hydrofluoric acid contained an unknown element, fluorine, related to chlorine and iodine. But every attempt to free it failed, and several experimenters were injured or killed by the poisonous and corrosive chemicals involved. Fluorine reacts with almost everything, even water, and the most promising starting material, pure liquid hydrogen fluoride, does not conduct electricity, so it cannot simply be split with a current.
Henri Moissan, a Paris pharmacist and chemist born in 1852 to a Jewish mother, took up the problem in 1884, working in borrowed laboratory space. He found that potassium fluoride dissolved in liquid hydrogen fluoride produced a mixture that stayed liquid and conducted electricity at low temperatures. He built an apparatus with electrodes of platinum and iridium, among the few materials that could survive, in a platinum vessel cooled to about minus 50 degrees Celsius. On June 26, 1886, he collected hydrogen at one electrode and pure fluorine gas at the other.
When a commission of the French Academy of Sciences came to watch, the experiment at first failed, because his freshly purified hydrogen fluoride lacked the trace of potassium fluoride that made it work. Moissan identified the problem and repeated the demonstration successfully. He then made a thorough study of the new element’s reactions. At the 1906 Nobel ceremony he was praised for the great experimental skill with which he had isolated and studied fluorine, the most violent of the elements.
Moissan’s method, the electrolysis of potassium fluoride dissolved in hydrogen fluoride, remains the basis of how fluorine is made commercially. Fluorine chemistry is now part of daily life. Fluorine is used to make uranium hexafluoride for enriching nuclear fuel, and fluorine compounds give us non-stick and chemically resistant plastics such as Teflon, refrigerants, insulating gases for high-voltage equipment and many modern medicines. Some fluorine compounds have also caused environmental harm, such as ozone-damaging refrigerants that were later phased out, which is part of the same story that began with Moissan’s experiment.
Why it matters
Fluorine is still produced by Moissan’s electrolytic method and goes into nuclear fuel, plastics, refrigeration and medicines.
About Henri Moissan
Paris chemist who first isolated fluorine, by a method still used to make it today, and built an electric arc furnace that opened high-temperature chemistry to science and industry. Nobel Prize 1906.
Sources
- Henri Moissan, Biographical NobelPrize.org
- Award ceremony speech, Nobel Prize in Chemistry 1906 NobelPrize.org
- Henri Moissan Wikipedia
- Fluorine Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.