Post by Anders Hoveland on May 17, 2011 20:53:51 GMT -8
Fluorine is the most reactive oxidizing element, but there do exist several fluorine compounds which are even stronger oxidizers than elemental fluorine.
Video Links
Video of fluorine gas spontaneously reacting with a variety of different elements:
www.youtube.com/watch?v=V1FsO5zaf6M
Here is a picture of fluorine reacting with a baked clay brick:
www.youtube.com/watch?v=wqLnSkLalOE&feature=related
Chemical Preparation of Fluorine and Chlorine Pentafluoride
MnF3 decomposes to manganese(II) fluoride above 600°C.
(2)KMnO4 + (2)KF + (10)HF + (3)H2O2 --> (2)K2MnF6 + (8)H2O + (3)O2
(solution is 50% aqueous HF, the potassium fluoromanganate precipitates out)
MnF3 itself hydrolyzes with water.
Potassium hexafluoronickelate likely coud be prepared in a similar reaction. At 400°C, a mixture of solid K2NiF6 and KF disproportionates/decomposes to form K3NiF6 and F2. (the reaction is reversible at 250°C).
Table of Reduction Potentials for Extreme Oxidizers
fluorine radicals (F• ) (reduced to fluoride ions) 3.6v
monoatomic oxygen (O: ) 2.42v
Ag+2 (dissolved in 6.5M perchloric acid to suppress hydrolysis) 1.987v
AgF2 dissolved in anhydrous HF can oxidize xenon to XeF2
AgF2+ , which is formed by first react fluorine radicals with KF and AgF, then reacting the resulting KAgF4 with BF3 or SbF5, is one of the two strongest known chemical oxidizers (the other is NiF3+ ). (excess SbF5 will cause the the KAgF4 to decompose to AgF+ and F2)
AgF3 has also been produced by reaction of AgF with O2F2 dissolved in chlorine pentafluoride. AgF2+ is also capable of oxidizing PtF6(-) to PtF6, which even KrF+ is unable to accomplish. NiF3+ is unable to oxidize Kr. PtF6 oxidizes oxygen to dioxygenyl ions ( O2+ ).
DANGER: F2 and HF are extremely poisonous!
Typically all the equipment must be made of monel (nickel-copper alloy) with teflon fittings. Although fluorine ignites on contact and easily burns through glass, stainless steel generally does not spontaneously react without ignition, although it can burn vigorously in the gas. Stainless steel valves have been used to handle fluorine gas, despite this danger. The inside of the valve must be free from any contaminants that could cause ignition of the steel. The valve is then gradually exposed to progressively increased concentrations of fluorine mixtures to oxidize any trace contaminants. Despite the precautions, for reasons not entirely understood, the valves have often spontaneously ignited when, after several minutes of operation without incident, the flow rate was suddenly increased.
Edit: the attachment below does not work, and this forum setup will not let me delete it. I really should get a better forum.
Video Links
Video of fluorine gas spontaneously reacting with a variety of different elements:
www.youtube.com/watch?v=V1FsO5zaf6M
Here is a picture of fluorine reacting with a baked clay brick:
www.youtube.com/watch?v=wqLnSkLalOE&feature=related
Chemical Preparation of Fluorine and Chlorine Pentafluoride
MnF3 decomposes to manganese(II) fluoride above 600°C.
(2)KMnO4 + (2)KF + (10)HF + (3)H2O2 --> (2)K2MnF6 + (8)H2O + (3)O2
(solution is 50% aqueous HF, the potassium fluoromanganate precipitates out)
MnF3 itself hydrolyzes with water.
Potassium hexafluoronickelate likely coud be prepared in a similar reaction. At 400°C, a mixture of solid K2NiF6 and KF disproportionates/decomposes to form K3NiF6 and F2. (the reaction is reversible at 250°C).
Table of Reduction Potentials for Extreme Oxidizers
fluorine radicals (F• ) (reduced to fluoride ions) 3.6v
monoatomic oxygen (O: ) 2.42v
Ag+2 (dissolved in 6.5M perchloric acid to suppress hydrolysis) 1.987v
AgF2 dissolved in anhydrous HF can oxidize xenon to XeF2
AgF2+ , which is formed by first react fluorine radicals with KF and AgF, then reacting the resulting KAgF4 with BF3 or SbF5, is one of the two strongest known chemical oxidizers (the other is NiF3+ ). (excess SbF5 will cause the the KAgF4 to decompose to AgF+ and F2)
AgF3 has also been produced by reaction of AgF with O2F2 dissolved in chlorine pentafluoride. AgF2+ is also capable of oxidizing PtF6(-) to PtF6, which even KrF+ is unable to accomplish. NiF3+ is unable to oxidize Kr. PtF6 oxidizes oxygen to dioxygenyl ions ( O2+ ).
DANGER: F2 and HF are extremely poisonous!
Typically all the equipment must be made of monel (nickel-copper alloy) with teflon fittings. Although fluorine ignites on contact and easily burns through glass, stainless steel generally does not spontaneously react without ignition, although it can burn vigorously in the gas. Stainless steel valves have been used to handle fluorine gas, despite this danger. The inside of the valve must be free from any contaminants that could cause ignition of the steel. The valve is then gradually exposed to progressively increased concentrations of fluorine mixtures to oxidize any trace contaminants. Despite the precautions, for reasons not entirely understood, the valves have often spontaneously ignited when, after several minutes of operation without incident, the flow rate was suddenly increased.
Edit: the attachment below does not work, and this forum setup will not let me delete it. I really should get a better forum.
Attachments:
