Phosphorus is believed to be a glow-in-the-dark mineral, poisonous and flammable. But this is only part of the truth about this amazing element. Phosphorus can also be different, with directly opposite properties.

What is red phosphorus?

Phosphorus can exist in several variants (allotropic forms), which differ greatly in their physical and chemical properties. The reason for this is the difference in structure. For example, the crystal lattice of white phosphorus is molecular, and the lattice of red phosphorus is atomic. Thanks to it, it reacts slowly with other substances, is stable in air under normal conditions (white phosphorus ignites in air). In total, more than twenty modifications were found in phosphorus, four of which are stable (white, red, black and metallic phosphorus), the rest are unstable.

Red phosphorus is a very interesting substance, a natural inorganic polymer with the formula (P 4) n and a very complex structure of pyramidally bonded atoms.

The properties of red phosphorus to some extent depend on the conditions for its preparation. By changing temperature, light, and catalysts, it is possible to create red phosphorus species with predictable properties.

The discoverer of red phosphorus is the Austrian A. Schroetter, who obtained it by heating a sealed ampoule with white phosphorus and carbon monoxide at a temperature of +500 °C.

Properties of red phosphorus

Red phosphorus is produced by heating white phosphorus for a long time high temperatures(250-300 °C) without air access. The color of the substance varies from purple-red to violet.

Red phosphorus, unlike its more well-known "brother", white phosphorus, is a solid, does not luminesce, is practically insoluble in anything (neither in water, nor in organic solvents, nor in carbon disulfide). It is not poisonous, ignites spontaneously in air only at a temperature of + 240-260 ° C (in fact, it is not red phosphorus itself that ignites, but its vapors, which, after cooling, turn into white flammable phosphorus).

The density of red phosphorus is higher than that of white and is equal to 2.0 - 2.4 g / cm3 (depending on the specific modification).

In the air, red phosphorus absorbs moisture, oxidizes, turning into an oxide; continuing to absorb moisture, it turns into thick phosphoric acid (“soaks”). In view of this, the reagent should be hermetically sealed, depriving access to air moisture. When heated, red phosphorus does not melt, but sublimates (evaporates). After condensation, the vapors of the substances turn into white phosphorus.

The use of red phosphorus

Red phosphorus is practically non-toxic and much safer in operation and storage than white phosphorus. Therefore, in industrial production phosphides, phosphorus-containing fertilizers, various derivatives of phosphoric acid, red phosphorus is most often used.

Red phosphorus itself is mainly used to make matches. It is included in the "grater" mixture, which is applied to the boxes. It is also used in lubricants, incendiary compositions, fuel, in the production of incandescent lamps.

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Phosphorus is known in several allotropic modifications: white, red, violet and black. In laboratory practice, one has to meet with white and red modifications.

White phosphorus is a solid. Under normal conditions, it is yellowish, soft and appearance looks like wax. It is easily oxidized and flammable. White phosphorus is poisonous - it leaves painful burns on the skin. White phosphorus goes on sale in the form of sticks of different lengths with a diameter of 0.5-2 cm.

White phosphorus is easily oxidized, and therefore it is stored under water in carefully sealed dark glass vessels in poorly lit and not very cold rooms (to avoid cracking the jars due to freezing water). The amount of oxygen contained in water and oxidizing phosphorus is very small; it is 7-14 mg per liter of water.

Under the influence of light, white phosphorus turns into red.

With slow oxidation, the glow of white phosphorus is observed, and with vigorous oxidation, it ignites.

White phosphorus is taken with tweezers or metal tongs; in no case should you touch it with your hands.

In case of a burn with white phosphorus, the burned area is washed with a solution of AgNO 3 (1:1) or KMnO 4 (1:10) and a wet dressing is applied soaked in the same solutions or a 5% solution of copper sulfate, then the wound is washed with water and after smoothing the epidermis, apply vaseline bandage with methyl violet. For severe burns, see a doctor.

Solutions of silver nitrate, potassium permanganate and copper sulfate oxidize white phosphorus and thus stop its damaging effect.

In case of white phosphorus poisoning, take a teaspoon of a 2% copper sulfate solution orally until vomiting occurs. Then, using the Mitcherlich test, based on the luminescence, the presence of phosphorus is determined. For this, water acidified with sulfuric acid is added to the vomiting of the poisoned person, and distilled in the dark; at the content of phosphorus, the glow of vapors is observed. A Wurtz flask is used as a device, to the side tube of which a Liebig condenser is attached, from where the distilled products enter the receiver. If phosphorus vapor is directed into a solution of silver nitrate, then a black precipitate of metallic silver forms, which is formed according to the equation given in the experiment on the reduction of silver salts with white phosphorus.

Already 0.1 G white phosphorus is a lethal dose for an adult.

White phosphorus is cut with a knife or scissors in a porcelain mortar under water. When using water at room temperature, phosphorus crumbles. Therefore it is better to use warm water, but not higher than 25-30°. After cutting the phosphorus in warm water, it is transferred to cold water or cooled with a stream of cold water.

White phosphorus is a highly flammable substance. It ignites at a temperature of 36-60°, depending on the concentration of oxygen in the air. Therefore, when conducting experiments, in order to avoid an accident, it is necessary to take into account every grain of it.

Drying of white phosphorus is carried out by quickly applying thin asbestos or filter paper to it, avoiding friction or pressure.

When phosphorus ignites, it is extinguished with sand, a wet towel or water. If burning phosphorus is on a sheet of paper (or asbestos), this sheet must not be touched, since molten burning phosphorus can be easily spilled.

White phosphorus melts at 44°, boils at 281°. White phosphorus is melted with water, because in contact with air, molten phosphorus ignites. By fusion and subsequent cooling, white phosphorus can be easily recovered from the waste. To do this, white phosphorus waste from various experiments, collected in a porcelain crucible with water, is heated in a water bath. If crust formation is noticeable on the surface of the molten phosphorus, a little HNO 3 or a chromium mixture is added. The crust is oxidized, small grains merge into a common mass, and after cooling with a jet of cold water, one piece of white phosphorus is obtained.

Under no circumstances should phosphorus residues be thrown into the sink, as, accumulating in the bends of the sewer elbow, it can cause burns to maintenance workers.

Experience. Melting and supercooling of molten white phosphorus. A piece of white phosphorus the size of a pea is placed in a test tube with water. The test tube is placed in a beaker filled almost to the top with water and fixed in a vertical position in a tripod clamp. The glass is slightly heated and using a thermometer determine the temperature of the water in the test tube at which phosphorus melts. After the end of melting, the test tube is transferred to a beaker with cold water and observe the solidification of phosphorus. If the tube is stationary, then at a temperature below 44° (up to 30°) white phosphorus remains in a liquid state.

The liquid state of white phosphorus, cooled below its melting point, is a state of supercooling.

After the end of the experiment, in order to more easily extract the phosphorus, it is melted again and the test tube is immersed with the hole up in an inclined position in a vessel with cold water.

Experience. Attaching a piece of white phosphorus to the end of the wire. To melt and solidify white phosphorus, a small porcelain crucible with phosphorus and water is used; it is placed in a glass of warm and then cold water. The wire for this purpose is taken iron or copper with a length of 25-30 cm and diameter 0.1-0.3 cm. When the wire is immersed in solidifying phosphorus, it easily attaches to it. In the absence of a crucible, a test tube is used. However, due to the insufficiently even surface of the test tube, it is sometimes necessary to break it in order to extract the phosphorus. To remove white phosphorus from the wire, it is immersed in a glass of warm water.

Experience. Definition specific gravity phosphorus. At 10°, the specific gravity of phosphorus is 1.83. Experience allows us to make sure that white phosphorus is heavier than water and lighter than concentrated H 2 SO 4.

When a small piece of white phosphorus is introduced into a test tube with water and concentrated H 2 SO 4 (specific weight 1.84), it is observed that phosphorus sinks in water, but floats on the surface of the acid, melting due to the heat released when concentrated H 2 SO is dissolved 4 in water.

To pour concentrated H 2 SO 4 into a test tube with water, use a funnel with a long and narrow neck, reaching to the end of the test tube. Pour in the acid and remove the funnel from the test tube carefully so as not to cause mixing of the liquids.

At the end of the experiment, the contents of the test tube are stirred with a glass rod and cooled from the outside with a stream of cold water until the phosphorus solidifies so that it can be removed from the test tube.

When using red phosphorus, it is observed that it sinks not only in water, but also in concentrated H 2 SO 4, since its specific gravity (2.35) is greater than the specific gravity of both water and concentrated sulfuric acid.

WHITE PHOSPHORUS, GLOW

Due to the slow oxidation that occurs even at ordinary temperatures, white phosphorus glows in the dark (hence the name "luminiferous"). Around a piece of phosphorus in the dark, a greenish luminous cloud appears, which, when the phosphorus vibrates, is set in a wave-like motion.

Phosphorescence (luminescence of phosphorus) is explained by the slow oxidation of phosphorus vapor by oxygen in the air to phosphorous and phosphorus anhydride with the release of light, but without the release of heat. In this case, ozone is released, and the air around is ionized (see the experiment showing the slow combustion of white phosphorus).

Phosphorescence depends on temperature and oxygen concentration. At 10° and normal pressure phosphorescence proceeds weakly, and in the absence of air does not occur at all.

Substances that react with ozone (H 2 S, SO 2, Cl 2, NH 3, C 2 H 4, turpentine oil) weaken or completely stop phosphorescence.

The conversion of chemical energy into light energy is called "chemiluminescence".

Experience. Observation of the glow of white phosphorus. If you observe in the dark a piece of white phosphorus in a glass and not completely covered with water, then a greenish glow is noticeable. In this case, wet phosphorus slowly oxidizes, but does not ignite, since the temperature of the water is below the flash point of white phosphorus.

The glow of white phosphorus can be observed after a piece of white phosphorus has been exposed to air for a short time. If you put a few pieces of white phosphorus in a flask on glass wool and fill the flask with carbon dioxide, lowering the end of the outlet tube to the bottom of the flask under glass wool, and then slightly heat the flask by dipping it into a vessel with warm water, then in the dark you can observe the formation of a cold pale greenish flame (you can safely put your hand into it).

The formation of a cold flame is explained by the fact that carbon dioxide leaving the flask entrains phosphorus vapor, which begins to oxidize when it comes into contact with air at the opening of the flask. In a flask, white phosphorus does not ignite, because it is in an atmosphere of carbon dioxide. At the end of the experiment, the flask is filled with water.

In describing the experiment for the production of white phosphorus in an atmosphere of hydrogen or carbon dioxide, it was already mentioned that carrying out these experiments in the dark makes it possible to observe the glow of white phosphorus.

If you make an inscription with phosphorus chalk on a wall, a sheet of cardboard or paper, then thanks to phosphorescence, the inscription remains visible for a long time in the dark.

Such an inscription cannot be made on a blackboard, because after that ordinary chalk does not stick to it and the board has to be washed with gasoline or another stearin solvent.

Phosphorus chalk is obtained by dissolving liquid white phosphorus in molten stearin or paraffin. To do this, approximately two parts by weight of stearin (candle pieces) or paraffin are added to a test tube to one weight part of dry white phosphorus, the test tube is covered with cotton wool to prevent oxygen from entering, and heated with continuous shaking. After the end of melting, the test tube is cooled with a jet of cold water, then the test tube is broken and the solidified mass is removed.

Phosphorus chalk is stored under water. When using a piece of such chalk is wrapped in wet paper.

Phosphorus chalk can also be obtained by adding small pieces of dried white phosphorus to paraffin (stearin) melted in a porcelain cup. If the paraffin ignites when phosphorus is added, it is extinguished by covering the cup with a piece of cardboard or asbestos.

After some cooling, the solution of phosphorus in paraffin is poured into dry and clean test tubes and cooled with a stream of cold water until it solidifies into a solid mass.

After that, test tubes are broken, chalk is removed and stored under water.

SOLUBILITY OF WHITE PHOSPHORUS

In water, white phosphorus is sparingly soluble, slightly soluble in alcohol, ether, benzene, xylene, methyl iodide and glycerin; dissolves well in carbon disulfide, sulfur chloride, phosphorus trichloride and tribromide, carbon tetrachloride.

Experience. Dissolution of white phosphorus in carbon disulfide. Carbon disulfide is a colorless, highly volatile, highly flammable, poisonous liquid. Therefore, when working with it, avoid inhaling its vapors and turn off all gas burners.

Three or four pieces of white phosphorus the size of a pea are dissolved with light shaking in a glass of 10-15 ml carbon disulfide.

If a small sheet of filter paper is moistened with this solution and held in air, the paper ignites after a while. This is because carbon disulfide evaporates quickly, and the finely divided white phosphorus remaining on the paper quickly oxidizes at ordinary temperatures and ignites due to the heat released during oxidation. (It is known that the ignition temperature of various substances depends on the degree of their grinding.) It happens that paper does not ignite, but only chars. Paper moistened with a solution of phosphorus in carbon disulfide is kept in air with metal tongs.

The experiment is carried out carefully so that drops of a solution of phosphorus in carbon disulfide do not fall on the floor, on the table, on clothes or on hands.

If the solution gets on the hand, it is quickly washed with soap and water, and then with a solution of KMnO 4 (to oxidize particles of white phosphorus that have fallen on the hands).

The solution of phosphorus in carbon disulfide remaining after the experiments is not stored in the laboratory, since it can easily ignite.

WHITE PHOSPHORUS TRANSFORMATION TO RED

White phosphorus is converted to red according to the equation:

P (white) = P (red) + 4 kcal.

Installation for the production of white phosphorus from red: test tube-reactor 1, tube 2, through which carbon dioxide enters the test tube-reactor, gas outlet tube 3, through which vapors of white phosphorus, together with carbon dioxide, leave the test tube and are cooled with water

The process of converting white phosphorus to red is greatly accelerated by heating, under the influence of light and in the presence of traces of iodine (1 G iodine at 400 G white phosphorus). Iodine, combining with phosphorus, forms phosphorus iodide, in which white phosphorus dissolves and quickly turns into red with the release of heat.

Red phosphorus is obtained by prolonged heating of white phosphorus in a closed vessel in the presence of traces of iodine to 280-340 °

With long-term storage of white phosphorus in the light, it gradually turns into red.

Experience. Obtaining a small amount of red phosphorus from white. In a glass tube 10-12 long, closed at one end cm and diameter 0.6-0.8 cm they introduce a piece of white phosphorus the size of a grain of wheat and a very small crystal of iodine. The tube is sealed and suspended in an air bath over a tray of sand, then heated to 280-340° and the transformation of white phosphorus into red is observed.

Partial conversion of white phosphorus to red can also be observed by slightly heating a test tube with a small piece of white phosphorus and a very small crystal of iodine. Before starting heating, the test tube is closed with a swab of glass (asbestos or ordinary) wool and a tray with sand is placed under the test tube. The tube is heated for 10-15 minutes (without bringing the phosphorus to a boil) and the transformation of white phosphorus into red is observed.

White phosphorus remaining in the test tube can be removed by heating with a concentrated alkali solution or by burning.

The transformation of white phosphorus into red can also be observed by heating a small piece of phosphorus in a test tube in an atmosphere of carbon dioxide to a temperature below boiling.

COMBUSTION OF WHITE PHOSPHORUS

When white phosphorus burns, phosphoric anhydride is formed:

P 4 + 5O 2 \u003d 2P 2 O 5 + 2 x 358.4 kcal.

You can observe the combustion of phosphorus in air (slow and fast) and under water.

Experience. Slow combustion of white phosphorus and air composition. This experiment was not described as a way to obtain nitrogen, since it does not completely bind the oxygen contained in the air.

The slow oxidation of white phosphorus by atmospheric oxygen occurs in two stages; in the first stage, phosphorous anhydride and ozone are formed according to the equations:

2P + 2O 2 \u003d P 2 O 3 + O, O + O 2 \u003d O 3.

In the second stage, phosphorous anhydride is oxidized to phosphoric anhydride.

The slow oxidation of white phosphorus is accompanied by luminescence and ionization of the surrounding air.

An experiment showing the slow burning of white phosphorus should last at least three hours. The apparatus required for the experiment is shown in Fig.

In a cylinder expanded at the opening, almost filled with water, a graduated tube with a closed end, containing about 10 ml water. Tube length 70 cm, diameter 1.5-2 cm. After lowering the graduated tube, remove the finger from the tube opening, bring the water in the tube and cylinder to the same level, and note the volume of air contained in the tube. Without raising the tube above the water level in the cylinder (in order not to let in additional air), a piece of white phosphorus fixed at the end of the wire is introduced into the air space of the tube.

After three to four hours, or even after two or three days, a rise in water in the tube is noted.

At the end of the experiment, the wire with phosphorus is removed from the tube (without raising the tube above the water level in the cylinder), the water in the tube and cylinder is brought to the same level, and the volume of air remaining after the slow oxidation of white phosphorus is noted.

Experience shows that as a result of the binding of oxygen by phosphorus, the volume of air has decreased by one fifth, which corresponds to the oxygen content in the air.

Experience. Rapid combustion of white phosphorus. Due to the fact that a large amount of heat is released during the reaction of the combination of phosphorus with oxygen, white phosphorus ignites spontaneously in air and burns with a bright yellowish-white flame, forming phosphorus anhydride, a white solid that combines very vigorously with water.

It was already mentioned earlier that white phosphorus ignites at 36-60 °. To observe its self-ignition and combustion, a piece of white phosphorus is placed on a sheet of asbestos and covered with a glass bell or a large funnel, on the neck of which a test tube is put on.

Phosphorus can be easily set on fire with a glass rod heated in hot water.

Experience. Comparison of ignition temperatures of white and red phosphorus. At one end of a copper plate (length 25 cm, width 2.5 cm and thickness 1 mm) put a small piece of dried white phosphorus, pour a small pile of red phosphorus on the other end. The plate is placed on a tripod and at the same time approximately equally burning gas burners are brought to both ends of the plate.

White phosphorus ignites immediately, and red phosphorus only when its temperature reaches approximately 240°.

Experience. Ignition of white phosphorus under water. A test tube with water containing several small pieces of white phosphorus is dipped into a beaker containing hot water. When the water in the test tube is heated to 30-50°C, a current of oxygen is passed into it through the tube. Phosphorus ignites and burns, scattering bright sparks.

If the experiment is carried out in the beaker itself (without a test tube), the beaker is placed on a tripod mounted on a tray of sand.

REDUCTION OF SILVER AND COPPER SALTS WITH WHITE PHOSPHORUS

Experience. When a piece of white phosphorus is introduced into a test tube with a solution of silver nitrate, a precipitate of metallic silver is observed (white phosphorus is an energetic reducing agent):

P + 5AgNO 3 + 4H 2 O \u003d H 3 RO 4 + 5Ag + 5HNO 3.

If white phosphorus is introduced into a test tube with a solution of copper sulfate, then metallic copper precipitates:

2P + 5CuSO 4 + 8H 2 O \u003d 2H 3 PO 4 + 5H 2 SO 4 + 5Cu.

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 quite by accident, by the alchemist Henning Brand, when he was trying to extract gold from urine. So phosphorus became the first element that alchemists were able to extract through their experiments.

Phosphorus characteristic

It is chemically very active, therefore, in nature it can only be found in the form of minerals - compounds with other elements, of which there are 190 species. Critical Connection- this is calcium phosphate Now there are many varieties of apatite, the most common of which is fluorapatite. From apatites various kinds sedimentary rocks- Phosphorites.

For living organisms, phosphorus has a very importance, since it is part of both plant and animal protein in the form of various compounds.

In plants, this element is found mainly in seed proteins, and in animal organisms - in various proteins of blood, milk, brain cells and A large number of Phosphorus is found as 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 rapidly cooling its vapor. Then a solid is formed. crystalline substance, which in its pure form is absolutely colorless and transparent. Commercially available white phosphorus is usually slightly yellowish in color and is very waxy in appearance. In the cold, this substance becomes brittle, and at temperatures above 15 degrees it becomes soft, and it can be easily cut with a knife.

White phosphorus does not dissolve in water, but lends itself well to organic solvents. In air, it oxidizes very quickly (begins to burn) and at the same time glows in the dark. Actually, ideas about a luminous substance and detective stories about are connected precisely with white phosphorus. He is strong poison which is deadly even in small doses.

Red phosphorus is a deep red solid that differs in properties from those described above. It oxidizes very slowly in air, does not glow in the dark, lights up only when heated, it cannot be dissolved in organic solvents, and it is not poisonous. With strong heating, at which there is no air access, it, without melting, turns into vapor, from which, when cooled, white phosphorus is obtained. When both elements burn, 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 types of this substance, it is the least active.

Sulfur crystalline Sulfur dioxide (in crystals)

Sulfur

Sulfur S is a hard, brittle, yellow crystalline substance with a melting point of 119.3°C. But do not confuse this sulfur with the sulfur on matches. On the heads of matches, there are mainly complex substances, one of which is potassium chlorate (KClO3), which is capable of self-ignition during friction or temperature. Sulfur- a simple substance and is present here as one of the components that make up the match head.

Sulfur modifications:

There are two modifications of sulfur: brittle sulfur And plastic sulfur. At 113 °C crystalline sulfur melts, turning into a yellow watery liquid. Molten sulfur at 187°C becomes very viscous and quickly darkens. At the same time, its structural state changes. And if you heat sulfur to 445 ° C, it boils. By pouring boiling sulfur in a thin stream into cold water, one can obtain plastic sulfur - a rubber-like modification consisting of polymer chains. In this state, sulfur is able to deform, stretch, while not collapsing. But as soon as she lies down in the air for several days, she turns back into a fragile material.

Sulfur dielectric. It can serve as a heat insulator.

Sulfur easily oxidizes almost all metals except gold Au, platinum Pt and ruthenium Ru. Sulfur oxidizes even at room temperature alkaline (sodium Na, potassium K, lithium Li, calcium Ca) and alkaline earth metals (aluminum Al, magnesium Mg). On air crystalline sulfur burns with a blue flame to form sulfur dioxide SO 2 (a gas with an unpleasant suffocating odor). When sulfur is burned in hydrogen, a poisonous gas is formed - hydrogen sulfide

Many products, when spoiled, give off a specific smell of hydrogen sulfide. Sulfur is used in industry to produce sulfuric acid. Oxidizing sulfur dioxide SO 2 in an environment enriched with oxygen, get sulfur trioxide SO 3 is a viscous transparent liquid.

Sulfuric anhydride or sulfur trioxide SO 3 at room temperature is a colorless, volatile liquid (bp = 45 ° C), which eventually turns into an asbestos-like modification, consisting of shiny silky crystals. Fibers of sulfuric anhydride are stable only in a sealed vessel. Absorbing air moisture, they turn into a thick colorless liquid - oleum (from Latin oleum - "oil"). Although formally oleum can be considered as a solution of SO 3 in H 2 SO 4.

Sulphur dioxide exhibits a strong bleaching effect: if, for example, a red rose is lowered into a container with sulfur dioxide SO 2, then it will lose its color.

Phosphorus

This substance can exist in two forms: red phosphorus And white phosphorus(white phosphorus is also called yellow phosphorus).

White phosphorus (or yellow phosphorus) is a poisonous, highly reactive, soft, waxy substance of pale yellow color, soluble in carbon disulfide and benzene. In air, white phosphorus ignites at 34°C and burns with a bright white flame to form phosphorus oxide. White phosphorus melts at 44.1°C and glows in the dark. May cause severe burns on contact with skin.

Very poisonous: a lethal dose of about 0.1 g (about the same for potassium cyanide - 0.12 g). Due to the danger of self-ignition in air, white phosphorus is stored under a layer of water. and black phosphorus are less toxic, since they are non-volatile and practically insoluble in water. White phosphorus is already at room temperature, and the remaining modifications of phosphorus - when heated, react with many simple substances: halogens (fluorine, chlorine, bromine, iodine, astatine) oxygen, sulfur, some metals. If you heat white phosphorus to 300 0 C without air, then it gradually turns into red phosphorus. Red phosphorus is a solid substance, non-toxic, does not glow in the dark and does not ignite spontaneously.

The name red phosphorus refers to several modifications at once, differing in density and color: it ranges from orange to dark red and even purple. All varieties red phosphorus insoluble in organic solvents, compared to white phosphorus, they are less reactive (red phosphorus ignites in air at t> 200 ° C)

Water does not dissolve phosphorus. It is usually dissolved in ethyl alcohol.

Under pressure of hundreds of atmospheres, black phosphorus is obtained, similar in properties to metal (it conducts electricity and glistens). black phosphorus has a crystal lattice similar to that of metals.

Why does phosphorus glow

If they say that phosphorus glows, then they mean only white phosphorus! In its molecule (tops of a pyramid with a triangle base), each vertex has a pair of electrons that are located outside the surface of an imaginary pyramid. Phosphorus atoms are "open" and easily accessible to any atoms of other elements - oxidizing agents (for example, oxygen from the air). The available electron pairs of phosphorus serve as a "bait" for any other atoms that are ready to attach a foreign electron (having a high electronegativity). White phosphorus glows for a reason - it oxidizes - first, oxygen atoms are located between the phosphorus atoms. This happens until all the free electron pairs join the oxygen. After that, white phosphorus ceases to glow and turns into phosphorus oxide P 2 O 5 .

Phosphorus oxide is a relatively stable substance, but it actively reacts with water, forming metaphosphoric acid HPO 3 and orthophosphoric acid H 3 PO 4

Phosphorus acids

When phosphorus oxide P 2 O 5 is dissolved in water, orthophosphoric acid H3PO4. This acid is one of the weak acids, therefore it does not react with most metals, but only removes the oxide film on their surface. It is often used in the repair of electrical equipment, soldering electronic circuit boards, etc. She happens to be a good remedy to remove rust.

Phosphorus forms two acids: one - phosphoric acid, the second - metaphosphoric(HPO 3). But the second acid is not a stable compound and quickly oxidizes, forming phosphoric acid.

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Spatial image of a part of the crystal lattice of arsenic. Each atom in the folded layer is single bonded to three other atoms.

White phosphorus causes painful and difficult to heal burns. It is possible to turn red phosphorus into white only by sublimation. Red phosphorus does not dissolve to any significant extent in any of the solvents.

White phosphorus glows in the air in the dark, has the ability to ignite spontaneously, and is very toxic. But if you heat it without access to air almost to a boil, then a substance of a red-violet color is formed, which is not poisonous, does not ignite in air, and does not glow in the dark. Both substances - white phosphorus and red phosphorus - consist of the same atoms, from the same chemical element- phosphorus. The proof is that when burning in oxygen, the same substance is formed - phosphoric anhydride.

White phosphorus is separated by extraction with benzene, phosphorous acid is oxidized to phosphoric acid with an excess of dichromate, then fluorine is distilled off with steam for 3-35 hours and is determined photometrically by weakening the color of the aluminum complex with arsenazo.

White phosphorus melts at 44 1 C, boils at 275 C; at 15 C it becomes soft like wax. Practically insoluble in water, soluble in organic solvents.

White phosphorus is very chemically active: it ignites spontaneously in a thin layer at ordinary temperatures, in pieces it ignites above 50 C, so it is stored under water.

White phosphorus and sulfur react when heated and form a compound - PiSs, which is used in the manufacture of matches. The molecule of this compound is shown x-ray studies, has a symmetry axis of the third order, and the low value of the heat of formation (close to zero) shows that the atoms in this case have their normal covalencies.

White phosphorus is used very limitedly: it is filled with incendiary shells, artillery shells And hand grenades that form smoke screens during the explosion. Glow in the dark compositions are made from it.

White phosphorus is superior in masking ability to all known smoke generators. The smoke is not poisonous and does not damage uniforms and equipment. Red phosphorus has less masking power.

White phosphorus is a solid, soft as wax, has a garlic smell, is insoluble in water, but readily soluble in carbon disulfide (CS2), extremely poisonous.

White phosphorus, as a highly flammable substance, can be used in military affairs for the manufacture of incendiary bombs, artillery, mortar shells, and smoke bombs.