Phosphorus and its compounds. Practical application of phosphorus compounds

Among biogenic elements, a special place should be given to phosphorus. Indeed, without it, the existence of such vital compounds as, for example, ATP or phospholipids, as well as many other organic substances, is impossible . Moreover, the inorganic of this element is very rich in various molecules. Phosphorus and its compounds are widely used in industry, are important participants in biological processes, are used in a wide range of human activities. Therefore, let us consider what the given element is, what is its simple matter and the most important compounds.

Phosphorus: the general characteristic of an element

The situation in the periodic table can be described in several paragraphs.

1. The fifth group, the main subgroup.
2. The third small period.
3. The serial number is 15.
4. The atomic mass is 30.974.
5. The electronic configuration of the atom is 1s ² 2s ² 2p ⁶ 3s ² 3p ³ .
6. Possible oxidation states from -3 to +5.
7. The chemical symbol is P, the pronunciation in the formulas "pe." The name of the element is phosphorus. The Latin name is Phosphorus.

The history of the discovery of this atom is rooted in the distant XII century. Already in the records of the alchemists there were information indicating the receipt of an unknown "glowing" substance. However, the year 1669 was the official date for the synthesis and discovery of phosphorus. The bankrupt merchant merchant Brand in his search for a philosophical stone accidentally synthesized a substance capable of producing a glow and burning with a bright blinding flame. He did this by repeatedly calcining human urine.

After it, independently of each other, by approximately the same methods, this element was obtained:

• I. Kunkel;
• R. Boyle;
• A. Marggraf;
• K. Scheele;
• A. Lavoisier.

Today, one of the most popular ways of synthesizing this substance is to recover from the corresponding phosphorus-containing minerals at high temperatures under the influence of carbon monoxide and silica. The process is carried out in special furnaces. Phosphorus and its compounds are very important substances for both living beings and for many syntheses in the chemical industry. Therefore, we should consider what the given element is as a simple matter and where in nature it is contained.

Simple substance phosphorus

It is difficult to name any particular compound when it comes to phosphorus. This is explained by the numerous allotropic modifications that this element has. There are four main types of simple matter of phosphorus.

1. White. This compound, the formula of which is P ₄ . It is a white volatile substance with a sharp unpleasant odor of garlic. Self-ignited in air at ordinary temperature. Burns with a glowing pale green light. Very toxic and dangerous for life. The chemical activity is extremely high, so it is obtained and stored under a layer of purified water. This is possible due to poor solubility in polar solvents. Best for this white phosphorus suits carbon disulphide and organic substances. When heated, it can pass into the next allotropic form - red phosphorus. When condensation and cooling of fumes is able to form strata. To the touch, fat, soft, easily cut with a knife, white (slightly yellowish). The melting point is 44 ^° C. Due to the chemical activity it is used in syntheses. But because of the virulence it has no wide industrial application.
2. Yellow. This is a poorly purified form of white phosphorus. It is even more poisonous, it also smells of garlic unpleasantly. It flares up and burns with a bright glowing green flame. These yellow or brown crystals in water do not dissolve completely, with complete oxidation, white smoke clouds are separated with the composition P ₄ O ₁₀ .
3. Red phosphorus and its compounds are the most common and most frequently used in the industry modification of this substance. A paste-like red mass, which at elevated pressure can pass into the form of violet crystals, is chemically inactive. It is a polymer that can dissolve only in certain metals and more in anything. At a temperature of 250 ^° C, it sublimes, passing into a white modification. Not as toxic as the previous forms. However, prolonged exposure to the body is toxic. It is used in the application of an incendiary coating on matchboxes. This is explained by the fact that it can not ignite spontaneously, but when it detonates and rubs it explodes (lights up).
4. The black. According to external data very similar graphite, also is greasy to the touch. It is a semiconductor of electric current. Dark crystals, shiny, which can not dissolve in any solvents at all. In order for it to catch fire, very high temperatures and preliminary incandescence are needed.

Also, not so long ago, an open form of phosphorus, metallic, is of interest. It is a conductor and has a cubic crystal lattice.

Chemical properties

The chemical properties of phosphorus depend on the form in which it is found. As already mentioned, the most active yellow and white modification. In general, phosphorus is able to interact with:

• Metals, forming phosphides and acting as an oxidizer;
• Nonmetals, acting as a reducing agent and forming volatile and non-volatile compounds of various kinds;
• Strong oxidants, passing into phosphoric acid ;
• With concentrated caustic alkalis by the type of disproportionation;
• With water at a very high temperature;
• With oxygen to form different oxides.

The chemical properties of phosphorus are similar to those of nitrogen. Because he is part of the group of pnictogens. However, the activity is several orders of magnitude higher, due to the variety of allotropic modifications.

Being in nature

As a biogenic element, phosphorus is very common. Its percentage in the earth's crust is 0.09%. This is a fairly large indicator. Where does this atom occur in nature? There are several main places to be mentioned:

• Green part of plants, their seeds and fruits;
• Animal tissues (muscles, bones, tooth enamel, many important organic compounds);
• Earth's crust;
• the soil;
• Rocks and minerals;
• sea water.

Thus it is possible to speak only about the connected forms, but not about a simple substance. After all, he is extremely active, and this does not allow him to be free. Among the minerals the richest in phosphorus are:

• English;
• Fluoroapatite;
• Svanbergite;
• Phosphorite and others.

The biological significance of this element can not be overestimated. After all, it is a part of such compounds as:

• Proteins;
• Phospholipids;
• DNA;
• RNA;
• Phosphoproteins;
• Enzymes.

That is, all those that are vital and from which the entire body is built as a whole. The daily norm for a normal adult is about 2 grams.

Phosphorus and its compounds

As very active, this element forms a variety of different substances. After all, it forms phosphides, and acts as a reducing agent. Due to this, it is difficult to name an element that would be inert when reacting with it. And therefore the formulas of phosphorus compounds are extremely diverse. You can bring several classes of substances in the formation of which he is an active participant.

1. Binary compounds - oxides, phosphides, volatile hydrogen compound, sulfide, nitride and others. For example: P ₂ O ₅ , PCL ₃ , P ₂ S ₃ , PH ₃ and others.
2. Complex substances: salts of all types (medium, acidic, basic, double, complex), acids. Example: H ₃ PO ₄ , Na ₃ PO ₄ , H ₄ P ₂ O ₆ , Ca (H ₂ PO ₄ ) ₂ , (NH ₄ ) ₂ HPO ₄ and others.
3. Oxygen-containing organic compounds: proteins, phospholipids, ATP, DNA, RNA and others.

Most of the indicated types of substances have important industrial and biological significance. The use of phosphorus and its compounds is possible both for medical purposes and for the production of quite ordinary household items.

Compounds with metals

Binary phosphorus compounds with metals and less electronegative non-metals are called phosphides. These are salt-like substances that have extreme instability when exposed to different agents. Rapid decomposition (hydrolysis) is caused even by ordinary water.

In addition, under the influence of non-concentrated acids, the decomposition of the substance into the corresponding products also occurs. For example, if we talk about the hydrolysis of calcium phosphide, then the products will be metal hydroxide and phosphine:

Ca ₃ P ₂ + 6H ₂ O = 3Ca (OH) ₂ + 2PH ₃ ↑

And by exposing the phosphide to decomposition under the action of a mineral acid, we get the corresponding salt and phosphine:

Ca ₃ P ₂ + 6HCL = 3CaCL ₂ + 2PH ₃ ↑

In general, the value of the compounds in question is precisely that as a result, a hydrogen compound of phosphorus is formed, whose properties will be considered below.

Volatile substances based on phosphorus

There are two main ones:

• White phosphorus;
• Phosphine.

About the first we have already mentioned above and the characteristics resulted. They said that it was a white, thick smoke, highly poisonous, unpleasantly smelling and self-igniting under normal conditions.

But what is phosphine? This is the most common and known volatile substance, which includes the element under consideration. It is binary, and the second participant is hydrogen. The formula of the hydrogen compound of phosphorus is PH ₃ , the name is phosphine.

The properties of this substance can be described as follows.

1. Volatile colorless gas.
2. Very poisonous.
3. Has the smell of rotten fish.
4. With water it does not interact and it dissolves very poorly in it. Very soluble in organics.
5. Under normal conditions, it is very chemically active.
6. Spontaneously ignites in air.
7. It is formed during the decomposition of metal phosphides.

Another name is phosphane. With it are connected the stories from the most ancient times. It's all about the "wandering lights" that people sometimes see and see now in cemeteries, swamps. Ball-like or candle-like lights that appear here and there, creating the impression of movement, were considered a bad omen and they were very afraid of superstitious people. The cause of this phenomenon, according to modern views of some scientists, can be considered spontaneous combustion of phosphine, which is formed naturally by decomposition of organic residues, both plant and animal. The gas comes out and, touching the oxygen of the air, lights up. The color and size of the flame can vary. Most often, these are greenish bright lights.

Obviously, all the volatile compounds of phosphorus are poisonous substances that are easily detected by a sharp unpleasant odor. This sign helps to avoid poisoning and unpleasant consequences.

Compounds with non-metals

If phosphorus behaves as a reducing agent, then we should talk about binary compounds with nonmetals. Most often they are more electronegative. Thus, several types of substances of this kind can be distinguished:

• A phosphorus and sulfur compound - phosphorus sulphide P ₂ S ₃ ;
• Phosphorus chloride III, V;
• Oxides and anhydride;
• Bromide and iodide and others.

Chemistry of phosphorus and its compounds is diverse, so it is difficult to identify the most important of them. If we talk specifically about the substances that form their phosphorus and nonmetals, then the most important are oxides and chlorides of different composition. They are used in chemical synthesis as dehydrating agents, as catalysts and so on.

Thus, one of the most powerful dehydrating agents is the highest phosphorus oxide , P ₂ O ₅ . It draws water so strongly that, with direct contact with it, there is a violent reaction with a strong noise accompaniment. The substance itself is a white, snow-like mass, closer to an amorphous state in the aggregate state.

Oxygen-containing organic compounds with phosphorus

It is known that organic chemistry by the number of compounds far surpasses the inorganic chemistry. This is due to the phenomenon of isomerism and the ability of carbon atoms to form a different structure of the chain of atoms, closing up with each other. Naturally, there is a certain order, that is, a classification to which all organic chemistry is subject. The connection classes are different, however, we are interested in one particular, directly related to the element in question. These are oxygen-containing compounds with phosphorus. These include:

• Coenzymes - NADP, ATP, FMN, pyridoxalphosphate and others;
• Proteins;
• Nucleic acids, since the phosphoric acid residue is part of the nucleotide;
• Phospholipids and phosphoproteins;
• Enzymes and catalysts.

The type of ion in which phosphorus participates in the formation of a molecule of these compounds is the PO ₄ ^3- , that is, the acidic residue of phosphoric acid. In the composition of some proteins, it enters in the form of a free atom or a simple ion.

For the normal vital activity of each living organism, this element and the organic compounds formed by it are extremely important and necessary. After all, without protein molecules, it is impossible to build any structural part of the body. And DNA and RNA are the main carriers and transmitters of hereditary information. In general, all connections must be present without fail.

Application of phosphorus in industry

The use of phosphorus and its compounds in industry can be characterized in several points.

1. Used in the production of matches, explosives, incendiary bombs, certain types of fuel, lubricants.
2. As an absorber of gases, as well as in the manufacture of incandescent lamps.
3. To protect metals from corrosion.
4. In agriculture as fertilizer soil.
5. As a means for softening water.
6. In chemical syntheses in the production of various substances.

The role in living organisms is reduced to participation in the processes of formation of tooth enamel and bones. Participation in the reactions of ana- and catabolism, as well as maintaining the buffering of the internal environment of the cell and biological fluids. It is the basis in the synthesis of DNA, RNA, phospholipids.