Due to its high reactivity to glass, hydrofluoric acid is stored in fluorinated plastic containers.

At high concentrations, HF molecules undergo homotype associations to form polyatomic ions (e.g., hydrogen fluoride, HF-

2) and protons, thereby greatly increasing the acidity. [20] This leads to the protonation of very strong acids such as hydrochloric, sulfuric, or nitric acids when concentrated hydrofluoric acid solutions are used. [21] Although hydrofluoric acid is considered a weak acid, it is highly corrosive and can even attack glass when hydrated. [20]

Due to the association, the acidity of hydrofluoric acid solution changes with the concentration, which refers to the influence of F- on HF. Dilute solutions are weakly acidic with an acid ionization constant Ka = 6.6×10−4 (or pKa = 3.18),[10] in contrast to the corresponding solutions of other hydrogen halides, which are strong acids (pKa 0). As shown by the measurement of Hammett's acidity function H0 [15] (or "effective pH"), concentrated solutions of hydrogen fluoride are much more acidic than this value would suggest. During autoionization in 100% liquid HF, H0 is estimated to be between -10.2 and -15.1, comparable to the value of -12 for sulfuric acid.