38% Hydrofluoric Acid

[lanrete]

Hi,

my laboratory specifies particularly that we use 38% HF as a standard to carry out QC checks on our titration equipment. Anyone knows what is the significance of HF at 38% concentration?

It is because i have tons of stock HF at 50% and 49% and thus i would rather use 50% to directly carry out the check than preparing 38% HF from 50% HF then carrying out the QC check.

So i want to know what is so special about HF at 38%?

[frosch45]

Not exactly sure, but HF can dissolve certain types of glass. It reacts with SiO2. 38% is less conc, and your titration equip may not be able to handle it at 50%.

[verode]

take care with HF

you must just add some water it's easy to now

[John Cuthber]

Verode, if you had wanted to point out that 38% is roughly the azeotropic concentration (35.6%) it might, possibly, just, have justified the necromancy.

[Flashman]

I was thinking azeotrope, and looked it up, for which I've got 35.35% as the magic number. Maybe it doesn't take long to boil down to that?

[hermanntrude]

could also be a specific gravity. acids were (and still are, sometimes) measured by their specific gravity (density). Often the "normal" concentration was a round number in baumes, but when converted to % it'd be something weird looking