Basic salts. Category 'borates'

Basic salts are a fairly large group of compounds. This group includes borates, halides, nitrites, sulfites. The group "basic salts" include carbonates, nitrates, sulfates.

The borate category includes several types of compounds. In particular, borates include metaboric (HBO2), orthoboric (H3BO3), as well as unselected polybic acids. In accordance with the number of boron atoms, these basic salts are separated into hexa-, tetra-, di-, monoborates, etc. Borates can be named according to the acids that form them, and the number of moles of B2O3, which is 1 mole from the main oxide.

The interaction of metals with salts (ammonium, alkali and other) at the degree of oxidation +1 assumes the formation, as a rule, of anhydrous and hydrated metaborates such as MBO2, pentaborates of MB5O8, tetraborates M2B4O7 and others.

Borates are colorless crystals or amorphous substances. Usually they differ in a low-symmetry structure - rhombic or monoclinic.

Anhydrous borates have a melting point between 500 and 2000 degrees. Metaborates of alkali metals, as well as meta- and orthoborates of alkaline-earth compounds, are among the most fusible. Most of the substances easily form glasses when the melts are cooled.

The loss of crystallization water in hydrated monoborates occurs at a temperature of about one hundred and eighty, and in polyborates it is three hundred to five hundred degrees. Complete dehydration leads to the formation of amorphous substances, which undergo crystallization at five hundred to eight hundred degrees. As a result of this "rearrangement", partial decomposition of the compounds and the separation of B2O3 occur.

Alkali metal borates are characterized by their ability to dissolve in water. In particular, this is inherent in penta- and metaborates. These basic salts are mostly easily decomposed by acids. In some cases, decomposition occurs under the influence of SO2 and CO2.

Borates of heavy and alkaline earth metals are able to interact with alkaline, carbonate and hydrocarbonate solutions. Anhydrous compounds are more chemically resistant than hydrated. With a number of alcohols, with glycerol, in particular, borates form complexes soluble in water. Under the influence of strong oxidizing agents, H2O2, in particular, or during electrochemical oxidation, conversion to pexoborates occurs.

About a hundred borates are known in nature. In general, they are salts of Mg, Na, Fe, Ca. It should be said that these elements are used widely enough. In particular, the chlorides of these elements are a kind of a substance such as "technical salt", which, in turn, is used in various industries.

Anhydrous borates are obtained by dehydration. Sintering or fusing of B2O3 with carbonates or metal oxides is also used. Single crystals are grown in molten oxides, for example Bi2O3. The production of hydrated borates is carried out by the reactions of the interconversion of poorly soluble compounds with aqueous solutions of metal borates of the alkaline group, by the neutralization of H3BO3 by hydroxides, oxides or carbonates of metals.

Borates are used in the preparation of other boron compounds. In particular, as components of the charge in the manufacture of glasses, enamels, glazes, ceramics. The compounds are used in the production of impregnations and fireproof coatings. Borates are used for refining as fluxes, for soldering and welding metals. They are used as fillers and pigments for paint products, mordants for dyeing, as well as inhibitors (retarding) corrosion, components of electrolytes, phosphors and others. The most commonly used are calcium and boron borates.