29 No. 2
Moissan’s Isolation of Fluorine
The French chemist Henri Moissan received the Nobel Prize for Chemistry in 1906 for his isolation and investigation of the element fluorine and for his introduction of the electric furnace in the preparation of metal carbides and other refractory materials. The competition to earn the favor from the members of the chemical section of the Royal Swedish Academy of Sciences was particularly tough that year: Moissan edged out by only one vote (5–4) no one less than Dmitri Mendeleev! Unfortunately, the famous Russian chemist never got another chance to win the coveted prize since he died of influenza on 2 February 1907, and Moissan himself passed away from acute appendicitis 18 days later, shortly after returning to Paris from his trip to Stockholm.
The synthesis of elemental fluorine in 1886 was no small feat and Moissan succeeded where many before him had failed. The key to the isolation of this most reactive of elements, l’enfant terrible of the periodic table, was to electrolize at -25 °C a solution of potassium hydrogen fluoride (KHF2) in liquid anhydrous hydrogen fluoride. Special platinum–iridium electrodes and a platinum U-shaped vessel capped with fluorite (CaF2) stoppers, not exactly run–of–the–mill equipment, were required to attain success. Moissan’s electrolytic cell, illustrated on the two French stamps accompanying this note, is currently on display at the Moissan Museum in the School of Pharmacy, Université René Descartes—Paris 5. Interestingly, the stamp issued in 1986 to commemorate the 100th anniversary of the preparation of the mighty halogen, shown above, displays the incorrect (reverse) chemical equation (i.e., the reaction of fluorine with hydrogen to produce hydrogen fluoride)!
Written by Daniel Rabinovich <email@example.com>.
last modified 9 April 2007.
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