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Author: Subject: Ammonium Bifluoride to Sodium Fluoride
Hazard to Self

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[*] posted on 15-6-2020 at 23:30
Ammonium Bifluoride to Sodium Fluoride

I might be able to get a small amount of ammonium bifluoride and I'm thinking of converting it to the safer sodium fluoride (hopefully more stable as well) for storage. I have no use for fluoride at the moment.

I have in mind using either NaOH (high solubility) or Na2CO3/NaHCO3 (lower solubility)

NH4HF2 + 2NaOH -> 2NaF + NH4OH + H2O
? NH4HF2 + 2NaHCO3 -> 2NaF + NH4HCO3 + CO2 + H2O
?? NH4HF2 + Na2CO3 -> ???

Not sure about the last 2 reactions ... I am also hoping no free ammonia will be released.

NaF has low solubility at 0 C compared to the ammonium salts, so I should be able to ppt out the NaF with some loss ...

Which would be a better method? Any comment or advice, with regards to safety as well? Cheers.
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International Hazard

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[*] posted on 16-6-2020 at 00:31

Sodium fluoride is very sparingly soluble so simply dissolve your ammonium fluoride in water (very soluble) and add equi molar amounts of sodium hydroxide and sodium chloride. Stand for a while and filter of the sodium fluoride and wash with water. Or you can use pure sodium hydroxide (2 moles) and get som e ammonia gas to boot :)

But ammonium bifluoride is much more useful than NaF. when molten it dissolves all sorts of refractory metal oxides. Its also quite stable if stored in a tightly closed polythene/ polypropylene jar.
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