Fluorine, F2, is a poisonous pale yellow gaseous element found in
Group VIIb (i.e. the
Halogen Group of elements) of the periodic table.
The liquid has a clear yellow colour.
- Atomic Number : 9
- Atomic Mass : 18.9984
- Melting Point : -219.62 degC
- Boiling Point : -188.1 degC
- Density : 1.7
Fluorine is a highly dangerous element, causing severe chemical burns
on contact with the skin.
- Fluorine was first identified by Scheele in 1771AD.
- Fluorine was first isolated by Moissan in 1886AD, when
he noted the inclusion of fluorine in crystals of fluorspar from
Fluorine is an element which widely distributed, but not very abundant.
However, because of its high reactivity is not found naturally in its
Fluorine occurs in
- Cryolite, Na3AlF6,
- Fluorspar, CaF2, and
- Fluorapatite, 3Ca3(PO4)2.Ca(ClF).
Fluorine can be prepared by the electrolysis of fused acid potassium
fluoride at 373 degK in a copper vessel using graphite electrodes.
The electrolyte, pure and dry acid potassium fluoride is fused in an
electrically heated vessel, such as a wide copper V-tube, the
electrodes are pure acheson graphite rods insulated in bakelite
cement stoppers. A current of 5 amperes at 12 volts is used.
The fluorine is purified by passage through two copper U-tubes, containing
dry sodium fluoride.
Fluorine is made on the industrial scale by the electrolysis of fused
acid potassium fluoride in a copper vessel using graphite electrodes
at currents up to 2,000 amperes. An anode current efficiency of
about 95% was attained. The fluorine gas is then piped in
steel or copper vessels and compressed up to 400 lb/in2 in nickel and steel cylinders.
- Fluorine is a light canary-yellow gas at room temperature.
- Fluorine is the most reactive and electronegative of all elements.
- Fluorine reacts explosively with hydrogen even in the dark and
at low temperature.
- Fluorine reacts violently with water forming hydrogen fluoride,
and liberates oxygen which is highly charged with ozone.
2 F2 + 2 H2O ==> 4 HF + O2
- Fluorine also reacts with sulphur, selenium, and tellurium,
which melt and ignite in the gas, forming halides.
- Fluorine is a powerful oxidising agent. For example, when fluorine
is bubbles through a solution of potassium chlorate this is oxidised
to potassium perchlorate.
F2 + 2 KClO3 + H2O ==> 2 HF + KClO4
- Fluorine does not react directly with oxygen, or nitrogen, and
combines with chlorine, only on heating, forming the gaseous products
chlorine fluoride, and chlorine trifluoride.
- Fluorine readily combines with bromine, and iodine, forming
colourless liquids BrF3 and IF5.
Fluorine is used in the synthesis of organic
Fluorine is used in the manufacture of Freon
(i.e. dichlorodifluoromethane, CCl2F2) which is used
as a refrigerant.
Fluorine is used in the manufacture of uranium
hexafluoride which is required for the separation
of the isotopes of uranium in centrifuges.
Detection and Analysis
Fluorine is detected by its corrosive action on
glass (i.e. the glass is etched).
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