White phosphorus, red and black - characteristics and application

Phosphorus is a fairly common chemical element on our planet. Its name translates as "light-bearing", because in its pure form it glows brightly in the dark. This element was discovered by chance, the alchemist Henning Brand, when he tried to extract gold from urine. Thus, phosphorus was the first element that alchemists could extract with the help of their experiments.

Characteristics of phosphorus

It is chemically very active, therefore in nature it can be found only in the form of minerals - compounds with other elements, which number 190 species. The most important compound is calcium phosphate (mineral apatite). Now many varieties of apatites are known, the most common of which is fluorapatite. Of apatites of different species, sedimentary rocks - phosphorites - form.

For living organisms, phosphorus is very important, because it is part of both vegetable and animal protein in the form of various compounds.

In plants, this element is found mainly in the proteins of the seed, and in the animal organisms - in various proteins of blood, milk, cells of the brain and nervous tissues. A large amount of phosphorus is contained in the form of calcium phosphate in the bones of vertebrates.

Phosphorus exists in three allotropic modifications: white phosphorus, red and black. Let's look at them in more detail.

White phosphorus can be obtained by quickly cooling its vapor. Then a solid crystalline substance is formed, which in pure form is absolutely colorless and transparent. White phosphorus, intended for sale, is usually painted slightly yellowish in color and looks very much like wax in appearance. In the cold, this substance becomes brittle, and at a temperature above 15 degrees it becomes soft, and it can easily be cut with a knife.

In water, white phosphorus does not dissolve, but it lends itself well to organic solvents. In air it oxidizes very quickly (starts to burn) and glows in the dark. Actually, the idea of a luminous substance and detective stories about the dog of the Baskervilles are associated with white phosphorus. It is a powerful poison that is deadly even in small doses.

Red phosphorus is a solid of dark red color, which in its properties is strikingly different from the one described above. It is oxidized very slowly in the air, it does not glow in the dark, it only lights up when heated, it is impossible to dissolve it in organic solvents, and it is not poisonous. With strong heating, in which there is no air access, it does not melt into steam, from which, when cooled, white phosphorus is obtained. When burning both elements, phosphorus oxide is formed, which proves the presence of the same element in their composition. In other words, they are formed by one element - phosphorus - and are its allotropic modifications.

Black phosphorus is obtained from white at 200 degrees Celsius under high pressure. It has a layered structure, metallic luster and looks like graphite. Of all the solid species of this substance, it is the least active.

Application of phosphorus

Modern production of phosphorus - about a million tons per year. The main producers: the USA, Holland, Canada, Germany.

The bulk of the phosphorus produced is used to produce thermal phosphoric acid, which is used in the production of fertilizers and phosphates. White phosphorus is used as a smoke-generating and incendiary means, including for tracer ammunition.

Red is used to make the incendiary surface of a matchbox, and in the production of incandescent lamps, it acts as a getter.

Phosphorus found its application in metallurgy. It is used as an additive for the production of alloyed alloys, solders, magnetically soft and antifriction alloys.