Methods for obtaining phosphorus and its compounds. Characteristics of phosphorus: finding in nature, features of physical and chemical properties, application. Allotropic modifications of phosphorus

allotropic modifications. Phosphorus forms several allotropic modifications. Of these, the most important are white, red and black phosphorus. The difference in the properties of the allotropic modifications of phosphorus is explained by their structure.

Chemical properties. Of all the allotropic modifications of phosphorus, the most active is white phosphorus. It oxidizes rapidly in air. Even at low heating, phosphorus ignites and burns out, releasing a large amount of heat: 4P + 502 = 2P2Os.

Phosphorus combines with many simple substances: oxygen, halogens, sulfur and some metals.

For example: 2P + 3S = P,S,; 2P + 5C12 = 2PC1,.

Application. In match production, in metallurgy, in the production of ammunition, for the production of certain semiconductors - gallium phosphide and indium phosphide, for the creation of preparations for the destruction of insect pests.

Phosphorus compounds

Phosphides. Compounds of phosphorus with metals. When phosphides interact with water, phosphine PH is released: Ca, P, + 6H20 \u003d 3Ca (OH). + 2PH,.

Phosphia. A highly poisonous gas with the smell of garlic. In chemical properties, it resembles ammonia, but is a stronger reducing agent.

Phosphorus oxide (U). Phosphorus (V) oxide has the appearance of a white snow-like mass. The density of its vapor corresponds to the formula P4O10, this formula reflects the actual composition of the molecule. Phosphorus (V) oxide easily combines with water, therefore it is used as a water-removing agent. In air, phosphorus oxide (V), attracting moisture, quickly turns into metaphosphoric acid: P40,n + 2H,0 = 4HPO,.

Orthophosphoric acid. It is a colorless, water-soluble crystals. Not poisonous. This is a medium strength acid.

Since it is tribasic, its dissociation into aqueous solutions proceeds in three stages. Phosphoric acid is not volatile and very stable: it does not have oxidizing properties. Therefore, it interacts with metals that are in the series of standard electrode potentials to the left of hydrogen.

salt phosphoric acid:

a) phosphates; they have replaced all hydrogen atoms in phosphoric acid. For example. CajCPOJj, K3P04;

b) hydrophosphates; in these salts, two hydrogen atoms of the acid are substituted. For example. K, HP04. CaHP04;

c) dihydrophosphates - one hydrogen atom in phosphoric acid is substituted. For example. KN, R04. Ca(H, P04),.

All dihydrogen phosphates are highly soluble in water. Most medium phosphates tend to be poorly soluble. Of the salts of this series, only sodium, potassium and ammonium phosphates are soluble. Hydrophosphates occupy an intermediate position in solubility: they are soluble better than phosphates, and worse than dihydrophosphates.

Phosphate fertilizers

Simple superphosphate. A mixture of calcium sulfate and calcium dihydrogen phosphate. To obtain this fertilizer, crushed phosphorite is mixed with sulfuric acid. As a result of the reaction, a mixture is formed that is highly soluble in water. This fertilizer is obtained from large quantities in the form of powder or granules.

Double superphosphate. concentrated phosphate fertilizer composition of Ca (H, GO4),. It is obtained by decomposition of natural phosphate with phosphoric acid. Double superphosphate does not contain calcium sulfate, which reduces the cost of its transportation and application to the soil.

Phosphate flour. Natural crushed mineral composition CaDPO^,. It is a yellowish or brown powder. Poorly soluble in water. Used on acidic podzolic soils.

Precipitate. Concentrated phosphorus fertilizer composition CaHP04 - 2H.0. It is poorly soluble in water, but readily soluble in organic acids. Reduces soil acidity. It is obtained by neutralizing phosphoric acid with a solution of calcium hydroxide.

More on Phosphorus:

1.1. Properties of elemental phosphorus. 1.1.1. Allotropy of phosphorus.
3.3.1. Kinetics of white phosphorus transformation in the presence of AlBn
1.1.4.1. Structure of red phosphorus - inorganic polymer.

The structure of the phosphorus atom The element of the VA group has the electronic formula 1s 2 2s 2 2p 6 3s 2 3p 3. Phosphorus is a non-metal. The most characteristic oxidation states: +5, +3, 0, -3. Oxides E 2 O 5 and E 2 O 3 have acid properties. Volatile hydrogen bond– Phosphine PH 3.

Allotropic modifications of phosphorus White phosphorus has a molecular crystal lattice; it is a yellowish substance with a garlic odor. In vapors, it has the composition P 4. It ignites in air at 18ºС. Turns red when stored in the light. It is insoluble in water, but highly soluble in carbon disulfide, benzene and other organic solvents. It is very poisonous: 0.1 g of white phosphorus is a lethal dose for humans.

The antidote for phosphorus poisoning is a 2% solution. blue vitriol, which should be given to the patient after 5 minutes in a teaspoon until vomiting occurs. Burning phosphorus not only causes very severe burns, but also causes poisoning of the tissues adjacent to the burn site, as a result of which healing is extremely slow. For burns with phosphorus, the antidote is a wet dressing soaked in a 5% solution of copper sulfate. Due to the fact that white phosphorus is easily oxidized and ignited, it is stored under water.

Red phosphorus is a powder with a weakly pronounced crystalline structure and therefore called amorphous, dark red in color, has an atomic lattice, is very hygroscopic (easily absorbs water), but is insoluble in water; it is also insoluble in carbon disulfide. Red phosphorus is obtained by prolonged heating of white phosphorus without air at 450ºС. Unlike white, it is not poisonous, has no smell, ignites at ºС.

Found in nature Phosphorus is an integral part of plant and animal proteins. In plants, phosphorus is concentrated in the seeds, in animals - in nervous tissue, muscles, skeleton. The human body contains about 1.5 kg of phosphorus: 1.4 kg in the bones, 130 g in the muscles and 13 g in the nervous tissue. The content of phosphorus in the human body is approximately 1% of body weight. The daily intake of phosphorus by a person is about 2 g.

Chemical properties of phosphorus B chemically white phosphorus is very different from red. White phosphorus is easily oxidized and spontaneously ignites in air, so it is stored under water. Red phosphorus does not ignite in air, but ignites when heated above 240ºС. When oxidized, white phosphorus glows in the dark - there is a direct conversion of chemical energy into light energy.

Phosphorus combines with many simple substances - oxygen, halogens, sulfur and some metals, showing oxidizing and reducing properties. 1. With oxygen. When burning phosphorus, white thick smoke is produced. White phosphorus ignites spontaneously in air, while red phosphorus burns when ignited. Phosphorus burns in oxygen with a blindingly bright flame. 4P + 3O 2 (lack) 2P 2 O 3 (P 4 O 6) 4P + 5O 2 (excess) 2P 2 O 5 (P 4 O 10)

2. With halogens. With elements that have a higher electronegativity than phosphorus, phosphorus reacts very vigorously. If red phosphorus is introduced into a vessel with chlorine, then after a few seconds it ignites spontaneously in chlorine. This usually produces phosphorus (III) chloride. 4P + 6Cl 2 (insufficient) 4PCl 3 4P + 10Cl 2 (excess) 4PCl 5

5. Red phosphorus is oxidized by water at a temperature of about 800ºС in the presence of a catalyst - copper powder: 2P + 8H 2 O 2H 3 PO 4 + 5H 2 6. Concentrated sulfuric acid oxidizes phosphorus when heated: t 2P + 5H 2 SO 4 (c) 5SO 2 + 2H 3 PO 4 + 2H 2 O 7. Nitric acid when heated, oxidizes phosphorus t P + 5HNO 3 (c) 5NO 2 + H 3 PO 4 + H 2 O 3P + 5HNO 3 (razb) + 2H 2 O 5NO + 3H 3 PO 4

Phosphorus production Phosphorus can be obtained by heating a mixture of phosphorite, coal and sand in an electric furnace. The equation is easier to compose if we imagine the flow in two stages: 1) Ca 3 (PO 4) 2 + 3SiO 2 P 2 O 5 + 3CaSiO 3 2) P 2 O 5 + 5C 2P + 5CO ______________________________________________ Ca 3 (PO 4) 2 + 5C + 3SiO 2 2P + 3CaSiO 3 + 5CO

Phosphine Phosphorus in the -3 oxidation state forms the hydrogen compound phosphine PH 3, similar to ammonia. This oxidation state is less characteristic of phosphorus than of nitrogen. Phosphine - a poisonous gas with a garlic odor, can be obtained from zinc phosphide by the action of acids or water: Zn 3 P 2 + 6HCl 2PH 3 + 3ZnCl 2 The main properties of phosphine are weaker than that of ammonia: PH 3 + HCl PH 4 Cl

Phosphonium salts in aqueous solutions are unstable: PH H 2 O PH 3 + H 3 O + Phosphine has reducing properties ( lowest degree phosphorus oxidation), burns in air (self-ignites): 2PH 3 + 4O 2 P 2 O 5 + 3H 2 O or PH 3 + 2O 2 H 3 PO 4 Phosphine is oxidized by many oxidizing agents PH 3 + 8HNO 3 (c) 8NO 2 + H 3 PO 4 + 4H 2 O Zinc phosphide is used as a zoocide for rodent control.

Phosphorus (V) oxide Phosphorus (V) oxide P 2 O 5 (or P 4 O 10) is formed during the combustion of phosphorus in air. 4P + 5O 2 2P 2 O 5 The solid crystalline substance P 2 O 5 is hygroscopic and is used as a dewatering agent. 1. When interacting with water, phosphorus (V) oxide forms in the cold metaphosphoric acid HPO 3, which has a polymeric structure: P 2 O 5 + H 2 O 2HPO 3

Orthophosphoric acid In industry, phosphoric acid is obtained by the action of sulfuric acid on phosphorite: Ca 3 (PO 4) 2 + 3H 2 SO 4 3CaSO 4 + 2H 3 PO 4 Orthophosphoric acid is a crystalline substance (appl = 42ºС), soluble in water. As a tribasic acid of medium strength, it dissociates in steps. It enters into many reactions characteristic of acids.

Chemical properties of phosphoric acid 1. With metals in the series of voltages of metals to hydrogen: 3Mg + 2H 3 PO 4 Mg 3 (PO 4) 2 + 3H 2 2. With basic oxides: 3CaO + 2H 3 PO 4 Ca 3 (PO 4 ) 2 + 3H 2 O 3. With bases and ammonia: H 3 PO 4 + NaOH NaH 2 PO 4 + H 2 OH 3 PO 4 + 2NaOH Na 2 HPO 4 + 2H 2 OH 3 PO 4 + 3NaOH Na 3 PO 4 + 3H 2 OH 3 PO 4 + NH 3 (NH 4) 2 HPO 4

Salts of phosphoric acid There are medium salts - phosphates (Na 3 PO 4) and acid salts- hydrophosphates (Na 2 HPO 4) and dihydrophosphates (NaH 2 PO 4). Water-soluble phosphates and hydrophosphates of alkali metals and ammonium. All dihydrogen phosphates are soluble in water. Phosphoric acid is displaced by stronger acids from its salts: Ca 3 (PO 4) 2 + 3H 2 SO 4 3CaSO 4 + 2H 3 PO 4 conc.

It was opened in the form of a mass similar to wax, And in the darkness it glowed like the light of distant stars. The alchemist was at his best, but how could it not be here - Try to get the Philosopher's Stone! But joy and chagrin go side by side, The stone does not give health and wealth. So was that glowing wax stone? Think guys, the question is not so simple. Mystery

Phosphorus is just as important as nitrogen. He participates in the great natural cycle of substances, and, if there were no phosphorus, vegetable and animal world would be completely different. However, phosphorus is found in natural conditions not so common, mainly in the form of minerals, and it accounts for 0.08% of the mass of the earth's crust. In terms of prevalence, it ranks thirteenth among other elements. It is interesting to note that in the human body, phosphorus accounts for approximately 1.16%. Of these, 0.75% goes to bone tissue, about 0.25% to muscle and about 0.15% to nervous tissue.
Phosphorus is rarely found in large quantities, and in general it should be classified as a trace element. It is not found in free form in nature, since it has a very important property - it is easily oxidized, but it is contained in many minerals, the number of which is already 190. The most important of them are fluorapatite, hydroxylapatite, and phosphorite. Vivianite, monazite, amblygonite, triphylite are somewhat rarer, and xenotite and torbernite are quite rare.

As for phosphorus minerals, they are divided into primary and secondary. Among the primary, the most common are apatites, which are mainly rocks of igneous origin. Chemical composition apatite - calcium phosphate containing a certain amount of fluoride and calcium chloride. This is what determines the existence of the minerals fluorapatite and chlorapatite. In addition, they contain from 5 to 36% P 2 0 5 . Usually these minerals are mostly found in the magma zone, but often they are found in places where igneous rocks come into contact with sedimentary ones. Of all the known phosphate deposits, the most significant are found in Norway and Brazil. A large domestic apatite deposit was discovered by academician A. E. Fersman in Khibiny in 1925. “Apatite is mainly a compound of phosphoric acid and calcium,” wrote A. E. Fersman. They called it apatite, which means "deceiver" in Greek. Either these are transparent crystals, to the smallest detail resembling beryl or even quartz, then these are dense masses, indistinguishable from simple limestone, then these are radially radiant balls, then the rock is granular and shiny, like coarse-grained marble.
As a result of the action of weathering processes, the vital activity of bacteria, and destruction by various soil acids, apatites pass into forms that are easily consumed by plants, and thus are involved in the biochemical cycle. It should be noted that phosphorus is absorbed only from dissolved salts of phosphoric acid. However, phosphorus is partially washed out of the soil, and a large amount of it, absorbed by plants, does not return back to the soil and is carried away along with the crop. All this leads to the gradual depletion of the soil. With the introduction of phosphate fertilizers into the soil, the yield increases.
Despite the significant demand for phosphate fertilizers, there does not seem to be much concern about the depletion of raw materials for their production. These fertilizers can be obtained by complex processing of mineral raw materials, bottom marine sediments and various geological rocks rich in phosphorus.
During the decomposition of phosphorus-rich compounds of organic origin, gaseous and liquid substances are often formed. Sometimes you can observe the release of gas with the smell of rotten fish - hydrogen phosphide, or phosphine, PH3. Simultaneously with phosphine, another product is formed - diphosphine, P 2 H 4, which is a liquid. The vapors of diphosphine ignite spontaneously and ignite the gaseous phosphine. This explains the appearance of the so-called "wandering lights" in places such as cemeteries, swamps.
"Wandering lights" and other cases of the glow of phosphorus and its compounds caused superstitious fear in many people who were not familiar with the essence of these phenomena. Here is what academician S.I. recalls about working with gaseous phosphorus. Volfkovich: “Phosphorus was obtained in electric oven installed at Moscow University on Mokhovaya Street. Since these experiments were then carried out in our country for the first time, I did not take the precautions that are necessary when working with gaseous phosphorus - a poisonous, self-igniting and luminous bluish element. During many hours of work at the electric furnace, part of the liberated gaseous phosphorus soaked my clothes and even shoes so much that when I walked from the university at night through the dark, then unlit streets of Moscow, my clothes radiated a bluish glow, and from under my shoes (during friction them on the pavement) sparks were struck.
Each time a crowd gathered behind me, among which, despite my explanations, there were quite a few people who saw in me a “newly appeared” representative underworld. Soon, among the inhabitants of the Mokhovaya Street area and throughout Moscow, fantastic stories about the luminous monk began to be passed from mouth to mouth ... "
Phosphine and diphosphine are quite rare in nature, and more often one has to deal with such phosphorus compounds as phosphorites. These are secondary phosphate minerals of organic origin, they play a special role important role in agriculture. On islands Pacific Ocean, in Chile and Peru they were formed on the basis of bird droppings-guano, which in a dry climate accumulates in thick layers, often exceeding a hundred meters.
The formation of phosphorites can also be associated with geological catastrophes, for example, with the ice age, when the death of animals was massive. Similar processes are also possible in the ocean during the mass death of marine fauna. Rapid change in hydrological conditions, which may be associated with various processes mountain building, in particular with the action of underwater volcanoes, undoubtedly, in some cases leads to the death of marine animals. Phosphorus from organic residues is partially absorbed by plants, but mostly, dissolving in sea water, it passes into mineral forms. Sea water contains phosphates in quite large quantities - 100-200 mg/m3. Under certain chemical processes in seawater, phosphates can precipitate and accumulate at the bottom. And when the seabed rises in different geological periods, phosphorite deposits turn out to be on land. In a similar way, a large domestic phosphorite deposit near Kara-Tau in Kazakhstan could have been formed. Phosphorites are also found in the Moscow region.

Phosphorus cycle in nature

A good explanation of the main stages of the phosphorus cycle in nature can be the words of a well-known scientist, one of the founders of the direction of domestic science on the study of phosphorus fertilizers Ya. V. Samoilov: “Phosphorus of our phosphorite deposits is of biochemical origin. From apatite, a mineral in which almost all of the phosphorus of the lithosphere was initially contained, this element passes into the body of plants, from plants into the body of animals, which are true phosphorus concentrators. After passing through a series of animal bodies, phosphorus finally drops out of the biochemical cycle and again returns to the mineral one. Under certain physical and geographical conditions, mass death of animal organisms occurs in the sea

The use of phosphorus

Finding in nature. Phosphorus is not found in nature in its pure form, as it is a chemically active element. In the form of compounds, it is widely distributed, making up about 0.1% of the earth's crust by mass. Of the natural compounds of phosphorus, the most important is calcium phosphate Ca3 (POj, - the main component of apatites and phosphorites. Allotropic modifications. Phosphorus forms several allotropic modifications. Of these, the most important are white, red and black phosphorus. The difference in the properties of allotropic modifications of phosphorus is explained by their structure "Chemical properties. Of all the allotropic modifications of phosphorus, white phosphorus has the highest activity. It quickly oxidizes in air. Even with low heating, phosphorus ignites and burns, releasing a large amount of heat: 4P + 502 \u003d 2P2Os. Phosphorus combines with many simple substances: oxygen, halogens, sulfur and some metals. For example: 2P + 3S = P, S,; 2P + 5C12 = 2PC1,. drugs for the destruction of insect pests. Phosphorus compounds. Phosphides. Phosphorus compounds handicap with metals. When phosphides interact with water, phosphine PH is released: Ca, P, + 6H20 \u003d 3Ca (OH). + 2PH, Phosphia. A highly poisonous gas with the smell of garlic. In chemical properties, it resembles ammonia, but is a stronger reducing agent. Phosphorus oxide (U). Phosphorus (V) oxide has the appearance of a white snow-like mass. The density of its vapor corresponds to the formula P4O10, this formula reflects the actual composition of the molecule. Phosphorus (V) oxide easily combines with water, therefore it is used as a water-removing agent. In air, phosphorus oxide (V), attracting moisture, quickly turns into metaphosphoric acid: P40, n + 2H, 0 \u003d 4HPO,. Orthophosphoric acid. It is a colorless, water-soluble crystals. Not poisonous. This is a medium strength acid. Since it is tribasic, its dissociation in aqueous solutions proceeds in three steps. Phosphoric acid is not volatile and very stable: it does not have oxidizing properties. Therefore, it interacts with metals that are in the series of standard electrode potentials to the left of hydrogen. Phosphoric acid salts: a) phosphates; they have replaced all hydrogen atoms in phosphoric acid. For example. CajCPOJj, K3P04; b) hydrophosphates; in these salts, two hydrogen atoms of the acid are substituted. For example. K, HP04. CaHP04; c) dihydrophosphates - one hydrogen atom in phosphoric acid is substituted. For example. KN, R04. Ca (H, P04). All dihydrogen phosphates are highly soluble in water. Most medium phosphates are, as a rule, poorly soluble. Of the salts of this series, only sodium, potassium and ammonium phosphates are soluble. Hydrophosphates occupy an intermediate position in solubility: they are soluble better than phosphates, and worse than dihydrophosphates. Phosphoric fertilizers Simple superphosphate. A mixture of calcium sulfate and calcium dihydrogen phosphate. To obtain this fertilizer, crushed phosphorite is mixed with sulfuric acid. As a result of the reaction, a mixture is formed that is highly soluble in water. This fertilizer is obtained in large quantities in the form of powder or granules. Double superphosphate. The concentrated phosphorus fertilizer of structure Ca (N, GO4),. It is obtained by decomposition of natural phosphate with phosphoric acid. There is no calcium sulfate in double superphosphate, which reduces the cost of its transportation and application to the soil. Phosphorite flour. Natural crushed mineral composition CaDPO^,. It is a yellowish or brown powder. Poorly soluble in water. Used on acidic podzolic soils. Precipitate. Concentrated phosphorus fertilizer composition CaHP04 - 2H.0. It is poorly soluble in water, but readily soluble in organic acids. Reduces soil acidity. It is obtained by neutralizing phosphoric acid with a solution of calcium hydroxide.oo

Chemical properties. Of all the allotropic modifications of phosphorus, white phosphorus has the highest activity. It oxidizes rapidly in air. Even at low heating, phosphorus ignites and burns out, releasing a large amount of heat: 4P + 502 = 2P20).

Phosphorus combines with many simple substances: oxygen, halogens, sulfur and some metals.

For example: 2P + ZB = P.5); 2P + 5C12 = 2PC15.

Phosphorus compounds

Phosphides. Compounds of phosphorus with metals. When phosphides interact with water, phosphine PH, is released: Ca, P, + 6H20 \u003d 3Ca (OH), + 2PH,.

Phosphip. A highly poisonous gas with the smell of garlic. In chemical properties, it resembles ammonia, but is a stronger reducing agent.

Phosphorus oxide (U). Phosphorus (V) oxide has the appearance of a white snow-like mass. Its vapor density corresponds to the formula P40 | (1, this formula reflects the actual composition of the molecule. Phosphorus (V) oxide easily combines with water, therefore it is used as a water-removing agent. In air, phosphorus (V) oxide, attracting moisture, quickly turns into metaphosphoric acid: Р40„, + 2Н,0 = 4НР03.

Orthophosphoric acid. It is a colorless, water-soluble crystals. Non-poisonous.

This is a medium strength acid. Since it is tribasic, its dissociation in aqueous solutions proceeds in three steps. Phosphoric acid is non-volatile and very stable: it does not have oxidizing properties. Therefore, it interacts with metals that are in the series of standard electrode potentials to the left of hydrogen.

Salts of phosphoric acid:

a) phosphates: all hydrogen atoms in phosphoric acid are replaced in them. For example. Ca3(PO^K3PO4;

b) hydrophosphates; in these salts, two hydrogen atoms of the acid are substituted. For example. K, HP04. Sanro;

c) dihydrophosphates - one hydrogen atom in phosphoric acid is substituted. For example, KN, ROG Ca (H, P04),.

All dihydrogen phosphates are highly soluble in water. Most medium phosphates tend to be poorly soluble. Of the salts of this series, only sodium, potassium and ammonium phosphates are soluble. Hydrophosphates occupy an intermediate position in terms of solubility: they are soluble better than phosphates, and worse than dihydrophosphates.

Phosphate fertilizers

Simple superphosphate. A mixture of calcium sulfate and calcium dihydrogen phosphate. To obtain this fertilizer, crushed phosphorite is mixed with sulfuric acid. As a result of the reaction, a mixture is formed that is highly soluble in water. Such fertilizer is obtained in large quantities in the form of powder or granules.

Double superphosphate. Concentrated phosphorus fertilizer composition Ca(H,PO4)g It is obtained by decomposition of natural phosphate with phosphoric acid. Double superphosphate does not contain calcium sulfate, which reduces the cost of its transportation and application to the soil.

Phosphate flour. Natural crushed mineral composition CaDPO^,. It is a yellowish or brown powder. Poorly soluble in water. Used on acidic podzolic soils.

Precipitate. Concentrated phosphorus fertilizer composition CaHP04 2H.0. It is poorly soluble in water, but readily soluble in organic acids. Reduces soil acidity. It is obtained by neutralizing phosphoric acid with a solution of calcium hydroxide.