Since hydrofluoric acid (HF) will eat through just about anything, in what and how is it stored?

Asked by: JJ True

Answer

This is a better question for chemists, and being a physicist, my answer can't be regarded as an 'expert' answer, but rather as the answer of a curious guy who messed around in the chemistry lab a lot in high school.

First, HF (hydrofluoric acid) has the property that it can eat through glass. Glass is mainly SiO₂, and since no element but F has the ability to dislodge oxygen from its bond, glass containers are used for all sorts of acids (HCl, H₂SO₄, HNO₃). HF can react with glass, so it doesn't work there. But, HF, due to the already strong bond between the H and F (F is too electronegative for its own good) is not a strong acid otherwise. It can only react very slowly with materials other than those containing ionic bonds. Thus, HF is stored in plastic containers (I have seen HF bottles), which are mainly organic compounds which contain few, if any, ionic bonds which would be affected by HF. Also, HF, due to the small molecule size can penetrate through human skin, and is very poisonous.
Answered by: Yasar Safkan, Ph.D. M.I.T., Software Engineer, Istanbul, Turkey