For a good approximation of the [HF] in the soluble salts, use the dissociation equilibrium for HF which is driven by the [H+] and salt concentration. To one significant figure, the dissociation constant (Ka) for HF is 7E-4. Research using 19F NMR showed dissociated fluoride (likely F-H-F -) in several of the compounds you noted.
Michael N. Cooper MS, MPH, CIH
Senior Managing Scientist
Exponent / Failure Analysis Associates
149 Commonwealth Drive
Menlo Park, California 94025
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At least the ammonium fluoride (I assume you mean ammonium bifouoride), which is used in a very dilute solution as a disinfectant in home/office fish tanks, has caused fatailties in children when a concentrated solution has been ingested. The poisoing seems to be the same as hydrogen fluoride/hydrofluoric acid poisoning, and what data are available indicate that the medical treatment should be the same.
Boron trifluoride (BF3) seems to act similarly to hydrogen fluoride.
I'd have to research the other 3 compounds you list. Perhaps someone else on the listserve is more familiar with them.
Alan H. Hall, M.D.
Date: Wed, 7 Apr 2010 12:54:51
Subject: Re: [DCHAS-L] HF hazards
Does anyone know if aqueous solutions of the following fluorine containing reagents pose an HF hazard risk?
hexafluorophosphate – (mildly acidic solution, pH ~6)
Ammonium hexafluoroaluminate – (mildly acidic solution, pH ~6)
Ammonium tetrafluoroborate – (mildly acidic solution, pH ~6)
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