Hydrofluoric acid

Hydrofluoric acid is most often produced as a 40% solution, but sometimes 50% or even 72% solutions are found. It is also called hydrofluoric acid or an aqueous solution of hydrogen fluoride. Its name was formed from fluorspar, from which, in turn, hydrogen fluoride is obtained.

Hydrofluoric acid is the formula of its HF. Visually, it is a colorless liquid, has a molar mass of 20,0063 g / mol and a density of 1.15 g / cm³. It is characterized by temperatures: melting - 83.6 ° C, boiling - 19.5 ° C. It is non-flammable and very toxic.

What are the characteristics of hydrofluoric acid? The formula of this substance suggests that it contains fluorine and hydrogen. It belongs to the second class of danger, since the fluorine formed during dissociation is toxic and dangerous for the environment around us.

Dissolving this acid in water generates heat in an amount of 59.1 kJ / mol. It reacts with many metals, forming fluorides. Interesting is the fact that even a small part of this acid can lower the standard freezing point of water. At low temperatures, hydrogen fluoride forms the following compound with water: H2O · HF, H2O · 2HF, and H2O · 4HF.

Despite the fact that hydrofluoric acid refers to the average strength of the acids, it corrodes the glass and silicate containers. In addition, it is the only substance in its class that interacts with SiO 2 (SiO 2). This oxide, in turn, is the basic material used for glass production. Hydrofluoric acid does not affect paraffin, so it is widely used in its storage. Currently, it is transported and stored only in polyethylene packaging or in a container made of rubber and lead. A high concentration (60%) of the acid can be transported in strong containers made of steel.

Metals that do not dissolve in it are: lead, platinum and gold. Technical hydrofluoric acid contains several impurities, among which the most common are such as Fe, Rb, As, and also H2SiF6, SO2. A good purification of the acid is obtained by transferring it to potassium hydrofluoride. Further, it is decomposed by heating and hydrogen fluoride in water is dissolved.

When working in laboratories, utensils and containers of polyethylene and Teflon are used, and large volumes of hydrofluoric acid are stored in steel, dense, hermetically sealed tanks, as well as in tanks or in ammonia-type cylinders, which necessarily have a protective color.

Hydrofluoric acid is dangerous to human health. She has a weak narcotic effect on the psyche. If for any reason it gets into the blood, then a severe form of poisoning with changes in the functions of the digestive system and pulmonary edema can not be avoided. Still, the hydrofluoric acid can lead to disruption of the heart and general intoxication of the body.

If it gets on the skin or in the eyes, it causes painful burns even at a low concentration. Especially unpleasant consequences for the penetration of acid under the fingernails, so work with it is necessary only in gloves and under a good hood.

If, however, the skin gets acid, then rinse it immediately under running water and treat calcium gluconate with 2.5% in the form of a gel. But this can not be stopped, it is urgent to see a doctor. He will prescribe intravenous injections with calcium chloride.

Where is this dangerous acid used? Currently, it is actively used in the destruction of rocks from silicate, for the dissolution of metals such as niobium, tantalum and zirconium. It acts as a catalyst for hydrogenation and dehydrogenation, as well as for the production of fluoroplastics, chladones and fluorosulfonic acid. It has found its application in the oil industry. It processes oil wells to increase oil production.