What acid corrodes glass

We also remember from the school chemistry course that all the beakers and flasks in the school laboratory were made of glass, since it does not react with most active compounds, such as acids. Acids interact mainly with metals, alkalis and salts, and glass is already oxidized silicon, it will not be possible to oxidize it a second time. In addition, silicon and oxygen are very strongly bonded to glass, and it is very difficult to break such a bond.

The only acid that can corrode glass is hydrofluoric acid, which is an aqueous solution of hydrogen fluoride (HF). What is it better or can be stronger? Not at all, it's just that the process is going a little differently. During the reaction, oxygen atoms are replaced by fluorine, which is an even stronger oxidant (SiO2 + 4HF = SiF4 (up arrow) + 2H2O). The output is silicon tetrachloride (gas) and water.

The name "fluoric" comes from the name of the mineral - fluorspar (CaF2), from which hydrogen fluoride is obtained. A unique feature of hydrofluoric acid is its ability to dissolve glass. Therefore, hydrofluoric acid is not stored in glass containers, but in plastic or Teflon-coated containers.

Hydrofluoric acid, although not a strong acid, is highly toxic and weakly narcotic. Upon contact with the skin at the first moment it does not cause severe pain, is easily and imperceptibly absorbed, but after a short time it causes swelling, pain, chemical burns and general toxic effects. Symptoms from exposure to weakly concentrated solutions may appear within a day or even more after contact with the skin. At the same time, there are practically no antidotes, therefore, when the skin receives a lethal dose of hydrogen fluoride, a person can live for several days on painkillers, but without hope of salvation.

In industry, hydrofluoric acid is used for glass etching, rock cleaning in the mining of rare metals, and many other areas.