BARIUM COMPOUNDS, in accordance with the position of barium in the alkaline earth subgroup of group II of the Mendeleev system, have a doubly charged ion Ba ∙∙ (except for barium peroxide BaO 2). Barium compounds are characterized by a high specific gravity, colorlessness if the anions are not colored, a green color of the flame and a small amount of complex compounds. Technically, the most important are oxide and peroxide, insoluble salts: barium carbonate, sulphate and chromic acid, and soluble salts: barium nitrate, barium chloride, etc. Soluble salts of barium are poisonous. Quantitatively, barium is determined in the form of BaSO 4 , but in view of the extreme fineness of the precipitates obtained at low temperatures, it is necessary to precipitate from a boiling solution slightly acidified with hydrochloric acid. If there is nitric acid in the solution, part of the precipitate goes into solution. In addition, the BaSO 4 precipitate can carry away part of the salts due to adsorption. To separate from strontium, barium is precipitated as BaSiF 6 . If the barium compounds are insoluble, then they are fused with potassium carbonate-sodium and, after washing the alloy with water, they are dissolved in acid. Barium compounds are most commonly found as the mineral barite; much less common is witherite - barium carbonate.

Barium oxide BaO- white solid, crystallizes in cubes, density 5.72-5.32, melting point 1580 °, forms a crystalline hydrate according to the formula:

BaO + 9H 2 O \u003d Ba (OH) 2 ∙ 8H 2 O.

Barium oxide is relatively well soluble: at 0 ° - 1.5 hours in 100 hours of water; at 10° - 2.2 hours, at 15° - 2.89 hours, at 20° - 3.48 hours, at 50° - 11.75 hours, at 80° - 90.77 hours. Oxide barium is obtained from barium nitrate by calcination; this results in a porous product suitable for the manufacture of peroxide from it. Heating is carried out in crucibles, in a muffle furnace, at first very carefully so that the crucibles do not burst. The release of nitrogen oxides begins after 4 hours, but for their final removal, the crucibles are ignited for several hours at white heat (nitrogen oxides by 30% can be used to obtain nitric acid). The product is very expensive, because expensive: starting material, crucibles that are only good for one time, fuel, etc. Extracting barium oxide from witherite (BaCO 3 \u003d BaO + CO 2) is much more difficult than burning lime, t to. the reverse addition of CO 2 occurs very easily; therefore, coal is mixed with witherite so that CO 2 passes into CO. If it is desirable to obtain a porous product, then it is necessary to strictly adhere to the firing temperature. To prevent sintering, barium nitrate, coal, tar or barium carbide are often added, i.e.

ВаСО 3 + Ba(NO 3) 2 + 2С = 2ВаО + 2NO 2 + 3СО

ЗВаСО 3 + ВаС 2 = 4ВаО + 5СО.

In addition, it is necessary to protect the product as much as possible from sintering with the walls of the crucible and from the influence of hot gases. Calcination in shaft furnaces gives a very pure product (95%) if the furnace is built from the material High Quality and heating is carried out by generator gas, which allows precise temperature control. In Italy, heating is used in electric furnaces, but, apparently, this produces "oxycarbide" and "barium", which, in addition to 80-85% barium oxide, contains 10-12% carbide and 3-5% barium cyanide.

Aqueous barium oxide, caustic barite Ba (OH) 2 , forms transparent monoclinic crystals

Va (OH) 2 ∙ 8H 2 0,

losing the last molecule of water only at dark red heat; with light red heat, BaO is obtained, and with incandescence in a stream of air, barium peroxide is obtained. A solution of caustic barium - a strong alkali - absorbs CO 2 from the air, forming insoluble CaCO 3. 100 g of the solution contains: at 0 ° - 1.48 g of BaO, at 10 ° - 2.17, at 15 ° - 2.89, at 20 ° - 3.36, at 50 ° - 10.5, at 80 ° - 4.76. Caustic barite is used to absorb CO 2, extract caustic alkalis from sulphate, extract sugar from molasses, etc. Caustic barite can be obtained by calcining witherite by passing water vapor, but it is easier to burn BaCO 3 and act on BaO with water; or a mixture of 60% BaO and 40% BaS, obtained by calcining BaSO 4 with coal, is dissolved in water, and Ba (OH) 2 is obtained not only from BaO, but also from a significant part of BaS due to hydrolysis:

2BaS + 2HOH = Ba(OH) 2 + Ba(SH) 2 .

The crystallized substance contains only 1% impurities. The old methods of adding iron or zinc oxides to BaS are no longer used. It is also proposed to obtain caustic barite by electrolysis of barium chloride or barium chlorate and perchlorate in the presence of a BaCO 3 precipitate, which is dissolved by the acid formed at the anode.

Barium peroxide BaO 2 - white, mother-of-pearl intergrowths of the smallest crystals, very slightly soluble in water (only 0.168 hours in 100 hours of water). To obtain peroxide, barium oxide is heated in inclined tubes or in special muffles, which can be precisely kept at the desired temperature (500-600 °), and air purified from CO 2 and moisture is blown in. The purest peroxide is obtained in the form of square crystals of BaO 2 ∙ 8H 2 O, for which technical peroxide is first triturated with water, transferred to a solution by adding weak hydrochloric acid and precipitated with a solution of caustic barite, or simply add 10 times more 8% barite solution . The purest peroxide is a grayish-greenish sintered mass, insoluble in water, but interacting with carbonic anhydride. When heated, BaO 2 decomposes into BaO and oxygen. The elasticity of oxygen over BaO 2 at 555 ° - 25 mm, at 790 ° - 670 mm. Peroxide powder can ignite fibrous materials. On sale there are: the best grade - with 90% BaO 2 and the average - with 80-85%, with the main impurity being BaO. The content of BaO 2 is determined by titration with a 1/10 N-th KMnO 4 solution of BaO 2 in very weak cold hydrochloric acid (specific gravity 1.01-1.05), having previously precipitated barium ions with weak sulfuric acid. It is also possible to titrate the barium peroxide isolated from potassium iodide with sodium iodide sulphate. Barium peroxide is used to produce hydrogen peroxide (and at the same time get stronger whitewash "blancfix") and to prepare disinfectants.

Barium nitrite Ba (NO 2) 2 ∙ H 2 O - hexagonal colorless hexagonal prisms, melting point 220°. At 0 ° in 100 hours of water, 58 hours are dissolved, at 35 ° - 97 hours. It is obtained by adding a solution of sodium nitrite (360 hours of 96% NaNO 2 in 1000 hours of water) to a mixture of 360 hours of NaNO 2 and 610 hours BaCl 2 . At a high temperature, NaCl crystallizes, with further cooling - Ba (NO 2) 2.

Barium nitrate Ba (NO 3) 2 - colorless transparent octahedrons, melt at 375°; 100 hours of water are soluble at 10 ° - 7 hours, at 20 ° - 9.2 hours, at 100 ° - 32.2 hours. When heated, it first passes into barium nitrite, and then into barium oxide. It is used: 1) for the preparation of barium peroxide, 2) for green lights in fireworks, 3) for some explosives. It is produced: 1) by exchange decomposition when a theoretical amount of sodium nitrate is added to a hot solution of barium chloride (30 ° V) and subsequent recrystallization, 2) by the interaction of witherite or barium sulfide with nitric acid, 3) by heating calcium nitrate with technical barium carbonate.

Barium permanganate - manganese greens, Kassel greens, rosenstiel greens. BaMnO 4 - durable green paint suitable for fresco painting; obtained by calcining a mixture of compounds of barium (caustic barite, barium nitrate or barium peroxide) and manganese (dioxide or oxide).

Barium sulfide BaS - grayish porous mass, easily oxidized and attracts carbonic anhydride and water; decomposes with water. It is used for the manufacture of most barium compounds (lithopon, strong whitewash, etc.), for the extraction of sugar from molasses and the shearing of wool from skins (depilatorium). For mining, they use the calcination of a mixture of heavy spar with coal at 600-800 °:

BaSO 4 + 2C = 2CO 2 + BaS,

while at a higher temperature twice as much coal is wasted. The main condition is the close contact of coal and spar, which is achieved by grinding spar with 30-37% coal and water in rotating mills. The firing is carried out in rotary kilns, such as those used for cement or soda production, and after short kilns a dusty chamber must be placed to deposit smoke and soot. The resulting product contains 60-70% substances soluble in water, 20-25% - soluble in acids and 5% residue. The resulting product is thrown hot into water or into an aqueous solution of 1-2% NaOH (36 ° B), where half goes into aqueous oxide Ba (OH) 2, and the other into hydrosulphurous Ba (SH) 2. This solution is used directly for the preparation of barium compounds (lithopone, etc.) or for the extraction of sugar. When the residue reacts with hydrochloric acid, barium chloride is obtained. At old-type factories, calcination is carried out in fireclay retorts, evenly covered by flame. Well-dried slabs of coal and spar mixed with water are loaded into retorts. As soon as the flames of burning carbon monoxide disappear, the plates are removed so that they fall into hermetically sealed iron boxes.

Barium sulfate BaS 2 O 3 ∙ H 2 O It is formed from barium sulfide: 1) with free access of air and 2) with exchange decomposition with sodium sulphate. It is used to establish titers during iodometry.

Barium sulfate BaSO 4 , heavy spar (“strong”, “mineral”, “new”, etc. whitewash), pure white, earthy, very heavy powder, practically insoluble in water and acids (solubility: at 18 ° in 1 liter of water - 2 .3 mg). Natural grind directly. The best colorless varieties are called "flower" spar; ultramarine is added to yellowish and pinkish. Sometimes the heavy spar is ground and heated with hydrochloric acid to remove the iron; or spar is fused with Na 2 SO 4 and separated from the alloy by the action of water. Artificially it is obtained: 1) as waste in the preparation of hydrogen peroxide; 2) from barium chloride by interaction: a) with sulfuric acid, which gives a rapidly precipitated precipitate, b) with sodium sulphide Na 2 SO 4 or with magnesium sulphide salt MgSO 4, which gives a powder that slowly precipitates and has a high covering power; during production, it is important to clean the sulfuric acid clean; 3) from witherite; if it is very pure, it can be ground directly by the action of H 2 SO 4 , but with the addition of 2% HCl; if witherite contains impurities, it is first dissolved in hydrochloric acid and then precipitated. Barium sulphate is used by Ch. arr. for coloring wallpaper colored paper, cardboard and especially for photographic papers, for light oil paints and varnish paints from coal, in the manufacture of artificial ivory and rubber, for mixing with food introduced into the stomach during radiography.

Barium carbonate BaCO 3 - mineral witherite (rhombic crystals) or artificially obtained in the form of the smallest sediment (specific gravity 4.3); more difficult to dissociate upon calcination than CaCO 3 ; at 1100° CO 2 pressure is only 20 mm. It is used to extract other barium compounds, in the manufacture of bricks and terracotta, porcelain, artificial marble and barite crystal. It is artificially prepared: 1) from a crude solution of barium sulfide by injecting carbonic anhydride; 2) heating barium sulfate with potash at 5 atm pressure; 3) upon decomposition of barium saccharate with carbonic anhydride.

Barium acetate Ba (C 2 H 3 O 2) 2 ∙ H 2 O - easily soluble crystals used in dyeing; are produced by the interaction of sodium sulphide or carbonate with acetic acid.

Barium fluoride BaF 2 - white powder, slightly soluble in water, melts at 1280°, obtained by dissolving barium carbonate or caustic in HF or boiling cryolite with aqueous barium oxide.

Barium chloride l 2 ∙ 2Н 2O- colorless flat rhombic plates (specific gravity 3.05), stable in air, sour in taste, poisonous; when heated, it is relatively easy to lose the first particle of water and much more difficult to lose the second; anhydrous BaCl 2 right. system melts at 962°. 100 hours of solution contains anhydrous salt:

ВаСl 2 is used for the manufacture of "durable" white and for the conversion of vitriol contained in ceramic products into insoluble BaSO 4; it is extracted from barite by calcining it with coal and calcium chloride in soda furnaces at 900-1000 ° in a reducing flame, and a 70% solution of calcium chloride can also be used, but solid calcium chloride is better:

BaSO 4 + 4C \u003d BaS + 4CO;

BaS + SaSl 2 \u003d YOUl 2 + CaS.

Properly produced, an almost black porous product with 50-56% BaCl 2 is obtained. After systematic leaching, the salt is crystallized (previously, a jet of carbonic anhydride is passed through) until hydrogen sulfide is completely removed and evaporated in vessels varnished inside. Crystals are separated by centrifugation. If anhydrous BaCl 2 is needed, then the salt is heated in vessels with stirrers to obtain very small crystals, which are then calcined, and 95% BaCl 2 is obtained. It is possible to obtain BaCl 2 by adding BaS powder to hydrochloric acid in closed vessels, from where it is necessary to remove the released hydrogen sulfide into the factory pipe or burn it to SO 2 using the latter for sulfuric acid. Of course, it is much more advantageous to act with hydrochloric acid on BaCO 3 .

Barium chlorate Ba(C lO 3) 2 ∙ H 2O- monoclinic prisms, highly soluble in cold and even better in hot water. Easily explodes when heated and on impact if mixed with a combustible substance. It is used in pyrotechnics for green flames. It is produced by electrolysis at 75° of a saturated solution of BaCl 2 , with a platinum anode and a graphite cathode.

BARIUM (Latin Barium), Ba, chemical element Group II of the short form (2nd group of the long form) periodic system; refers to alkaline earth metals; atomic number 56, atomic mass 137.327. There are 7 stable nuclides in nature, among which 138 Ba prevails (71.7%); about 30 nuclides are obtained artificially.

Historical reference. Barium in the form of oxide was discovered in 1774 by K. Scheele, who discovered a previously unknown "earth", later called "heavy earth" - barite (from the Greek βαρ?ς - heavy). In 1808, G. Davy obtained metallic barium in the form of an amalgam by electrolysis of molten salts.

Distribution in nature. The content of barium in the earth's crust is 5·10 -2% by weight. Due to its high chemical activity, it does not occur in free form. The main minerals are barite BaSO 4 and witherite BaSO 3 . World production of BaSO 4 is about 6 million tons/year.

Properties. The configuration of the outer electron shell of the barium atom is 6s 2 ; in compounds it exhibits an oxidation state of +2, rarely +1; Pauling electronegativity 0.89; the atomic radius is 217.3 nm, the radius of the Ba 2+ ion is 149 pm (coordination number 6). Ionization energy Ba 0 → Ba + → Ba 2+ 502.8 and 965.1 kJ / mol. The standard electrode potential of a pair of Ba 2+ / Ba in an aqueous solution is -2.906 V.

Barium is a silvery white malleable metal; t pl 729 °С, t ΚИΠ 1637 °С. At normal pressure, the crystal lattice of barium is body-centered cubic; at 19 °C and 5530 MPa, a hexagonal modification is formed. At 293 K, barium density is 3594 kg / m 3, thermal conductivity is 18.4 W / (m K), electrical resistance 5 10 -7 Ohm m. Barium is paramagnetic; specific magnetic susceptibility 1.9·10 -9 m 3 /kg.

Barium metal oxidizes rapidly in air; it is stored in kerosene or under a layer of paraffin. Barium reacts at ordinary temperature with oxygen, forming barium oxide BaO, and with halogens, forming halides. By calcining BaO in a stream of oxygen or air at 500 ° C, peroxide BaO 2 is obtained (decomposes to BaO at 800 ° C). Reactions with nitrogen and hydrogen require heating; the reaction products are Ba 3 N 2 nitride and BaH 2 hydride. Barium reacts with water vapor even in the cold; dissolves vigorously in water, giving hydroxide Ba (OH) 2, which has the properties of alkalis. Barium forms salts with dilute acids. Of the most widely used barium salts, soluble in water are: BaCl 2 chloride and other halides, Ba(NO 3) 2 nitrate, Ba(ClO 3) 2 chlorate, Ba(OOCH 3) 2 acetate, BaS sulfide; poorly soluble - sulfate BaS0 4, carbonate BaCO 3, chromate BaCrO 4. Barium reduces the oxides, halides and sulfides of many metals to the corresponding metal. Barium forms alloys with most metals, sometimes alloys contain intermetallic compounds. Thus, BaAl, BaAl 2 , BaAl 4 were found in the Ba-Al system.

Soluble barium salts are toxic; practically non-toxic BaSO 4 .

Receipt. The main raw material for the production of barium is barite concentrate (80-95%) BaSO 4 , which is reduced with coal, coke or natural combustible gas; the resulting barium sulfide is processed into other salts of this element. By calcining barium compounds, BaO is obtained. Commercially pure metal barium (96-98% by weight) is obtained by thermal reduction of BaO oxide with Al powder. By distillation in vacuum, barium is purified to an impurity content of less than 10-4%, by zone melting - up to 10-6%. Another method for obtaining barium from BaO is the electrolysis of an oxide melt. Small amounts of barium are obtained by the reduction of beryllate BaBeO 2 at 1300 ° C with titanium.

Application. Barium is used as a deoxidizer for copper and lead, as an additive to anti-friction alloys, ferrous and non-ferrous metals, as well as to alloys used for the manufacture of typographic fonts in order to increase their hardness. Barium-nickel alloys are used to make spark plug electrodes in internal combustion engines and radio tubes. An alloy of barium with aluminum - alba, containing 56% Ba, the basis of the getters. Barium metal - material for anodes in chemical current sources. The active part of most thermionic cathodes is barium oxide. Barium peroxide is used as an oxidizer, bleach, in pyrotechnics; previously it was used to regenerate oxygen from CO 2 . Barium hexaferrite BaFe 12 O 19 is a promising material for use in information storage devices; BaFe 12 O 19 is used to make permanent magnets. BaSO 4 is introduced into drilling fluids during oil and gas production. Barium titanate BaTiO 3 is one of the most important ferroelectrics. Nuclide 140 Va (β-emitter, T 1/2 12.8 days) is an isotope tracer used to study barium compounds. Since barium compounds absorb X-rays and γ-radiation well, they are introduced into the composition of protective materials for X-ray installations and nuclear reactors. BaSO 4 is used as a contrast agent for x-ray studies of the gastrointestinal tract.

Lit. : Akhmetov TG Chemistry and technology of barium compounds. M., 1974; Tretyakov Yu.D. etc. Inorganic chemistry. M., 2001.

D. D. Zaitsev, Yu. D. Tretyakov.

Barium- element main subgroup the second group, the sixth period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 56. It is designated by the symbol Ba (lat. Barium). A simple substance is a soft, ductile silver-white alkaline earth metal. Possesses high chemical activity. History of the discovery of barium

1 element of the periodic table Barium was discovered in the form of oxide BaO in 1774 by Karl Scheele. In 1808, the English chemist Humphrey Davy produced a barium amalgam by electrolysis of wet barium hydroxide with a mercury cathode; after evaporating the mercury on heating, he isolated barium metal.
In 1774, the Swedish chemist Carl Wilhelm Scheele and his friend Johan Gottlieb Hahn investigated one of the heaviest minerals, heavy spar BaSO4. They managed to isolate the previously unknown "heavy earth", which was later called barite (from the Greek βαρυς - heavy). And after 34 years, Humphry Davy, having subjected wet barite earth to electrolysis, obtained from it a new element - barium. It should be noted that in the same 1808, a little earlier than Davy, Jene Jacob Berzelius and his co-workers obtained amalgams of calcium, strontium and barium. This is how the element barium was born.

Ancient alchemists calcined BaSO4 with wood or charcoal and obtained phosphorescent "Bolognese gems". But chemically, these gems are not BaO, but barium sulfide BaS.
It got its name from the Greek barys - "heavy", since its oxide (BaO) was characterized as having an unusually high density for such substances.
The earth's crust contains 0.05% barium. This is quite a lot - much more than, say, lead, tin, copper or mercury. In its pure form, it does not exist in the earth: barium is active, it is included in the subgroup of alkaline earth metals and, naturally, it is quite firmly bound in minerals.
The main minerals of barium are the already mentioned heavy spar BaSO4 (more often called barite) and witherite BaCO3, named after the Englishman William Withering (1741 ... 1799), who discovered this mineral in 1782. Many mineral waters and sea water. The low content in this case is a plus, not a minus, because all barium salts, except for sulfate, are poisonous.

The content of the article

BARIUM- a chemical element of the 2nd group of the periodic system, atomic number 56, relative atomic mass 137.33. It is located in the sixth period between cesium and lanthanum. Natural barium consists of seven stable isotopes with mass numbers 130(0.101%), 132(0.097%), 134(2.42%), 135(6.59%), 136(7.81%), 137(11, 32%) and 138 (71.66%). Barium in most chemical compounds exhibits a maximum oxidation state of +2, but it can also have zero. In nature, barium occurs only in the divalent state.

Discovery history.

In 1602, Casciarolo (a Bolognese shoemaker and alchemist) picked up a stone in the surrounding mountains, which is so heavy that Casciarolo suspected gold in it. Trying to isolate the gold from the stone, the alchemist calcined it with charcoal. Although it was not possible to isolate gold in this case, the experiment brought clearly encouraging results: the cooled calcination product glowed in the dark with a reddish color. The news of such an unusual find made a real sensation in the alchemical environment and an unusual mineral, which received a number of names - sun stone (Lapis solaris), Bologna stone (Lapis Boloniensis), Bologna phosphorus (Phosphorum Boloniensis) became a participant in various experiments. But time passed, and gold did not even think to stand out, so interest in the new mineral gradually disappeared, and for a long time it was considered a modified form of gypsum or lime. Only a century and a half later, in 1774, the famous Swedish chemists Karl Scheele and Johan Gan closely studied the “Bologna stone” and found that it contained some kind of “heavy earth”. Later, in 1779, Giton de Morvo called this “land” barot (barote) from the Greek word “barue" - heavy, and later changed the name to barite (baryte). Barium earth appeared under this name in chemistry textbooks of the late 18th and early 19th centuries. So, for example, in the textbook by A.L. Lavoisier (1789), barite is included in the list of salt-forming earthy simple bodies, and another name for barite is given - “heavy earth” (terre pesante, lat. terra ponderosa). The still unknown metal contained in the mineral began to be called barium (Latin - Barium). In Russian literature of the 19th century. the names barite and barium were also used. The next well-known barium mineral was natural barium carbonate, discovered in 1782 by Withering and later named witherite in his honor. Barium metal was first obtained by the Englishman Humphry Davy in 1808 by electrolysis of wet barium hydroxide with a mercury cathode and subsequent evaporation of mercury from barium amalgam. It should be noted that in the same 1808, somewhat earlier than Davy, the Swedish chemist Jens Berzelius received a barium amalgam. Despite its name, barium turned out to be a relatively light metal with a density of 3.78 g / cm 3, so in 1816 the English chemist Clarke proposed to reject the name "barium" on the grounds that if barium earth (barium oxide) is really heavier than other earths (oxides), the metal, on the contrary, is lighter than other metals. Clarke wanted to name this element plutonium in honor of the ancient Roman god, the ruler of the underworld Pluto, but this proposal was not supported by other scientists and the light metal continued to be called "heavy".

barium in nature.

The earth's crust contains 0.065% barium, it is found in the form of sulfate, carbonate, silicates and aluminosilicates. The main minerals of barium are barite (barium sulfate), already mentioned above, also called heavy or Persian spar, and witherite (barium carbonate). World mineral resources of barite were estimated in 1999 at 2 billion tons, a significant part of them is concentrated in China (about 1 billion tons) and Kazakhstan (0.5 billion tons). There are also large reserves of barite in the USA, India, Turkey, Morocco and Mexico. Russian resources barite is estimated at 10 million tons, its extraction is carried out at three main deposits located in Khakassia, Kemerovo and Chelyabinsk regions. The total annual production of barite in the world is about 7 million tons, Russia produces 5 thousand tons and imports 25 thousand tons of barite per year.

Receipt.

The main raw materials for obtaining barium and its compounds are barite and, more rarely, witherite. Restoring these minerals with coal, coke or natural gas, respectively, barium sulfide and oxide are obtained:

BaSO4 + 4C = BaS + 4CO

BaSO 4 + 2CH 4 \u003d BaS + 2C + 4H 2 O

BaCO 3 + C = BaO + 2CO

Barium metal is obtained by reducing it with aluminum oxide.

3BaO + 2Al = 3Ba + Al 2 O 3

For the first time this process was carried out by the Russian physical chemist N.N. Beketov. Here is how he described his experiments: “I took anhydrous barium oxide and, adding to it a certain amount of barium chloride, like a flux, put this mixture together with pieces of clay (aluminum) in a coal crucible and heated it for several hours. After cooling the crucible, I found in it a metal alloy of a completely different kind and physical properties than clay. This alloy has a macrocrystalline structure, is very brittle, a fresh fracture has a slight yellowish sheen; analysis showed that it consists of 33.3 barium and 66.7 clay for 100 hours, or, in other words, it contained two parts of clay for one part of barium ... ". Now the reduction process with aluminum is carried out in a vacuum at temperatures from 1100 to 1250 ° C, while the resulting barium evaporates and condenses on the colder parts of the reactor.

In addition, barium can be obtained by electrolysis of a molten mixture of barium and calcium chlorides.

Simple substance.

Barium is a silvery-white malleable metal that shatters when struck hard. Melting point 727°C, boiling point 1637°C, density 3.780 g/cm 3 . At normal pressure, it exists in two allotropic modifications: up to 375 ° C, a -Ba is stable with a cubic body-centered lattice, above 375 ° C, b -Ba is stable. At elevated pressure, a hexagonal modification is formed. Barium metal has a high chemical activity, it is intensively oxidized in air, forming a film containing BaO, BaO 2 and Ba 3 N 2, ignites upon slight heating or on impact.

2Ba + O 2 \u003d 2BaO; Ba + O 2 \u003d BaO 2; 3Ba + N 2 \u003d Ba 3 N 2,

therefore, barium is stored under a layer of kerosene or paraffin. Barium reacts vigorously with water and acid solutions, forming barium hydroxide or the corresponding salts:

Ba + 2H 2 O \u003d Ba (OH) 2 + H 2

Ba + 2HCl \u003d BaCl 2 + H 2

With halogens, barium forms halides, with hydrogen and nitrogen, when heated, it forms hydride and nitride, respectively.

Ba + Cl 2 \u003d BaCl 2; Ba + H 2 = BaH 2

Barium metal dissolves in liquid ammonia with the formation of a dark blue solution, from which ammonia Ba (NH 3) 6 can be isolated - crystals with a golden sheen, easily decomposing with the release of ammonia. In this compound, barium has a zero oxidation state.

Application in industry and science.

The use of metallic barium is very limited due to its high chemical activity; barium compounds are used much more widely. An alloy of barium with aluminum - an alloy of alba containing 56% Ba - the basis of getters (absorbers of residual gases in vacuum technology). To obtain the getter itself, barium is evaporated from the alloy by heating it in an evacuated flask of the device; as a result, a "barium mirror" is formed on the cold parts of the flask. In small quantities, barium is used in metallurgy to purify molten copper and lead from impurities of sulfur, oxygen and nitrogen. Barium is added to printing and anti-friction alloys, and an alloy of barium and nickel is used to make parts for radio tubes and electrodes for spark plugs in carburetor engines. In addition, there are non-standard applications of barium. One of them is the creation of artificial comets: released from spacecraft barium vapor is easily ionized sunbeams and turn into a bright plasma cloud. The first artificial comet was created in 1959 during the flight of the Soviet automatic interplanetary station Luna-1. In the early 1970s, German and American physicists, conducting research on electro magnetic field Earth, thrown over the territory of Colombia 15 kilograms of the smallest powder of barium. The resulting plasma cloud extended along the lines of the magnetic field, making it possible to refine their position. In 1979 barium particle jets were used to study the aurora.

barium compounds.

Divalent barium compounds are of the greatest practical interest.

barium oxide(BaO): an intermediate product in the production of barium - a refractory (melting point about 2020 ° C) white powder, reacts with water, forming barium hydroxide, absorbs carbon dioxide from the air, turning into carbonate:

BaO + H 2 O \u003d Ba (OH) 2; BaO + CO 2 = BaCO 3

When calcined in air at a temperature of 500–600° C, barium oxide reacts with oxygen, forming peroxide, which, upon further heating to 700° C, again turns into oxide, splitting off oxygen:

2BaO + O 2 \u003d 2BaO 2; 2BaO 2 \u003d 2BaO + O 2

Oxygen was obtained in this way until the end of the 19th century, until a method was developed for isolating oxygen by distillation of liquid air.

In the laboratory, barium oxide can be obtained by calcining barium nitrate:

2Ba(NO 3) 2 = 2BaO + 4NO 2 + O 2

Now barium oxide is used as a water-removing agent, to obtain barium peroxide and to manufacture ceramic magnets from barium ferrate (for this, a mixture of barium and iron oxide powders is sintered under pressure in a strong magnetic field), but the main application of barium oxide is the manufacture of thermionic cathodes. In 1903, the young German scientist Wenelt tested the law of electron emission from solids, discovered shortly before by the English physicist Richardson. The first of the experiments with platinum wire fully confirmed the law, but the control experiment failed: the electron flux was sharply higher than expected. Since the properties of the metal could not change, Wehnelt assumed that there was some kind of impurity on the surface of the platinum. After trying possible surface contaminants, he was convinced that barium oxide, which was part of the lubricant of the vacuum pump used in the experiment, emitted additional electrons. However, the scientific world did not immediately recognize this discovery, since its observation could not be reproduced. Only almost a quarter of a century later, the Englishman Kohler showed that for the manifestation of high thermionic emission, barium oxide must be heated at very low oxygen pressures. This phenomenon could only be explained in 1935. The German scientist Pohl suggested that electrons are emitted by a small impurity of barium in the oxide: at low pressures, part of the oxygen escapes from the oxide, and the remaining barium is easily ionized to form free electrons that leave the crystal when heated:

2BaO \u003d 2Ba + O 2; Ba = Ba 2+ + 2е

The correctness of this hypothesis was finally established in the late 1950s by Soviet chemists A. Bundel and P. Kovtun, who measured the barium impurity concentration in the oxide and compared it with the electron thermal emission flux. Now barium oxide is the active active part of most thermionic cathodes. For example, an electron beam that forms an image on a TV screen or computer monitor is emitted by barium oxide.

Barium hydroxide, octahydrate(Ba(OH)2· 8H2O). White powder, highly soluble in hot water (more than 50% at 80°C), worse in cold water (3.7% at 20°C). The melting point of the octahydrate is 78° C; when heated to 130° C, it transforms into anhydrous Ba(OH) 2 . Barium hydroxide is obtained by dissolving the oxide in hot water or by heating barium sulfide in a stream of superheated steam. Barium hydroxide reacts readily with carbon dioxide, so its aqueous solution, called "barite water" is used in analytical chemistry as a reagent for CO 2 . In addition, "barite water" serves as a reagent for sulfate and carbonate ions. Barium hydroxide is used to remove sulfate ions from vegetable and animal oils and industrial solutions, to obtain rubidium and cesium hydroxides, as a lubricant component.

barium carbonate(BaCO3). In nature, the mineral is witherite. White powder, insoluble in water, soluble in strong acids (except sulfuric). When heated to 1000 ° C, it decomposes with the release of CO 2:

BaCO 3 \u003d BaO + CO 2

Barium carbonate is added to glass to increase its refractive index, and is added to enamels and glazes.

barium sulfate(BaSO4). In nature - barite (heavy or Persian spar) - the main mineral of barium - a white powder (melting point about 1680 ° C), practically insoluble in water (2.2 mg / l at 18 ° C), slowly soluble in concentrated sulfuric acid.

The production of paints has long been associated with barium sulfate. True, at first its use was of a criminal nature: in crushed form, barite was mixed with white lead, which significantly reduced the cost of the final product and, at the same time, worsened the quality of the paint. However, such modified white was sold at the same price as regular white, generating significant profits for dye mill owners. Back in 1859, the Department of Manufactories and Internal Trade received information about the fraudulent machinations of Yaroslavl breeders, who added heavy spar to lead white, which “deceives consumers about the true quality of the product, and a request was also received to prohibit the said breeders from using spar when making lead white. ". But these complaints came to nothing. Suffice it to say that in 1882 a spar plant was founded in Yaroslavl, which, in 1885, produced 50 thousand pounds of crushed heavy spar. In the early 1890s, D.I. Mendeleev wrote: “... Barite is mixed with whitewash at many factories, since whitewash imported from abroad, to reduce the price, contains this admixture.”

Barium sulphate is part of Lithopone, a non-toxic white paint with high hiding power, which is widely demanded on the market. To make lithopone, mix aqueous solutions barium sulfide and zinc sulfate, while an exchange reaction occurs and a mixture of finely crystalline barium sulfate and zinc sulfide - lithopon - precipitates, and pure water remains in the solution.

BaS + ZnSO 4 \u003d BaSO 4 Ї + ZnSЇ

In the production of expensive grades of paper, barium sulfate plays the role of a filler and weighting agent, making the paper whiter and denser; it is also used as a filler in rubbers and ceramics.

More than 95% of the world's mined barite is used to prepare working fluids for deep well drilling.

Barium sulfate strongly absorbs x-rays and gamma rays. This property is widely used in medicine for the diagnosis of gastrointestinal diseases. To do this, the patient is allowed to swallow a suspension of barium sulfate in water or its mixture with semolina - "barium porridge" and then shine through x-rays. Those parts of the digestive tract, through which the "barium porridge" passes, look like dark spots in the picture. So the doctor can get an idea about the shape of the stomach and intestines, determine the place of occurrence of the disease. Barium sulfate is also used to make barite concrete used in the construction of nuclear power plants and nuclear plants to protect against penetrating radiation.

barium sulfide(BaS). An intermediate product in the production of barium and its compounds. The commercial product is a gray friable powder, poorly soluble in water. Barium sulfide is used to obtain lithopone, in the leather industry to remove hair from skins, to obtain pure hydrogen sulfide. BaS is a component of many phosphors - substances that glow after absorbing light energy. It was he who received Casciarolo, calcining barite with coal. By itself, barium sulfide does not glow: additives of activating substances are needed - salts of bismuth, lead and other metals.

barium titanate(BaTio 3). One of the most industrially important compounds of barium is white refractory (melting point 1616 ° C) crystalline substance, insoluble in water. Barium titanate is obtained by fusing titanium dioxide with barium carbonate at a temperature of about 1300 ° C:

BaCO 3 + TiO 2 \u003d BaTiO 3 + CO 2

Barium titanate is one of the best ferroelectrics (), very valuable electrical materials. In 1944, the Soviet physicist B.M. Vul discovered outstanding ferroelectric abilities (very high dielectric constant) in barium titanate, which retained them in a wide temperature range - almost from absolute zero to + 125 ° C. This circumstance, as well as high mechanical strength and The moisture resistance of barium titanate has made it one of the most important ferroelectrics used, for example, in the manufacture of electrical capacitors. Barium titanate, like all ferroelectrics, also has piezoelectric properties: it changes its electrical characteristics under pressure. Under the action of an alternating electric field, oscillations occur in its crystals, and therefore they are used in piezoelectric elements, radio circuits and automatic systems. Barium titanate has been used in attempts to detect gravitational waves.

Other barium compounds.

Barium nitrate and chlorate (Ba(ClO 3) 2) are an integral part of fireworks, the addition of these compounds gives the flame a bright green color. Barium peroxide is part of the ignition mixtures for aluminothermy. Tetracyanoplatinate (II) barium (Ba) glows under the influence of x-rays and gamma rays. In 1895, the German physicist Wilhelm Roentgen, observing the glow of this substance, suggested the existence of a new radiation, later called X-ray. Now barium tetracyanoplatinate(II) is used to cover luminous instrument screens. Barium thiosulfate (BaS 2 O 3) gives a colorless varnish a pearl hue, and by mixing it with glue, you can achieve a complete imitation of mother-of-pearl.

Toxicology of barium compounds.

All soluble barium salts are poisonous. Barium sulfate, used in fluoroscopy, is practically non-toxic. The lethal dose of barium chloride is 0.8-0.9 g, barium carbonate - 2-4 g. When toxic barium compounds are ingested, there is a burning sensation in the mouth, pain in the stomach, salivation, nausea, vomiting, dizziness, muscle weakness, shortness of breath , slow pulse and fall blood pressure. The main treatment for barium poisoning is gastric lavage and the use of laxatives.

The main sources of barium in the human body are food (especially seafood) and drinking water. According to the recommendations of the World Health Organization, the content of barium in drinking water should not exceed 0.7 mg/l, in Russia there are much more stringent standards - 0.1 mg/l.

Yuri Krutyakov

Barium

BARIUM-I; m.[lat. Barium from Greek. barys - heavy].

1. Chemical element (Ba), soft silvery-white reactive metal (used in engineering, industry, medicine).

2. Razg. About the sulfate salt of this element (taken orally as a contrast agent during x-ray examination of the stomach, intestines, etc.). Drink a glass of barium.

◁ Barium, -th, -th (1 sign). B salts. B. cathode.

(lat. Barium), a chemical element of group II of the periodic system, belongs to the alkaline earth metals. The name is from the Greek barýs - heavy. Silvery white soft metal; density 3.78 g / cm 3, t pl 727°C. Chemically very active, ignites when heated. Minerals: barite and witherite. They are used in vacuum technology as a gas absorber, in alloys (printing, bearing); barium salts - in the production of paints, glasses, enamels, in pyrotechnics, medicine.

BARIUM (lat. Baryum), Ba (read "barium"), a chemical element with atomic number 56, atomic mass 137.327. It is located in the sixth period in group IIA of the periodic system. Refers to alkaline earth elements. Natural barium consists of seven stable isotopes with mass numbers 130 (0.101%), 132 (0.097%), 134 (2.42%), 135 (6.59%), 136 (7.81%), 137 (11, 32%) and 138 (71.66%). Outer electron layer configuration 6 s 2 . The oxidation state is +2 (valency II). The radius of the atom is 0.221 nm, the radius of the Ba 2+ ion is 0.138 nm. The sequential ionization energies are 5.212, 10.004 and 35.844 eV. Electronegativity according to Pauling (cm. PAULING Linus) 0,9.
Discovery history
The name of the element comes from the Greek "baris" - heavy. In 1602, a Bolognese artisan drew attention to the heavy mineral barite. (cm. BARITE) BaSO 4 (density 4.50 kg / dm 3). In 1774 the Swede K. Scheele (cm. SCHEELE Karl Wilhelm), calcining barite, received the oxide BaO. Only in 1808 the Englishman G. Davy (cm. DEVI Humphrey) used electrolysis to recover active metals from their salt melts.
Prevalence in nature
The content in the earth's crust is 0.065%. The most important minerals are barite and witherite (cm. VITERITE) BaCO 3 .
Receipt
The main raw material for obtaining barium and its compounds is barite concentrate (80-95% BaSO 4). It is heated in a saturated solution of soda Na 2 CO 3:
BaSO 4 + Na 2 CO 3 \u003d BaCO 3 + Na 2 SO 4
The precipitate of acid-soluble barium carbonate is processed further.
Basic industrial method obtaining metallic barium - its reduction with aluminum powder (cm. ALUMINUM) at 1000-1200 °C:
4ВаО + 2Аl = 3Ва + ВаOАl 2 О 3
By reducing barite with coal or coke when heated, BaS is obtained:
BaSO 4 + 4C \u003d BaS + 4CO
The resulting water-soluble barium sulfide is processed into other barium compounds, Ba (OH) 2, BaCO 3, Ba (NO 3) 2.
Physical and chemical properties
Barium is a silvery-white malleable metal, the crystal lattice is cubic, body-centered, A= 0.501 nm. At a temperature of 375 °C, it passes into the b-modification. Melting point 727 ° C, boiling point 1637 ° C, density 3.780 g / cm 3. The standard electrode potential Ba 2+ / Ba is -2.906 V.
It has high chemical activity. Intensively oxidized in air, forming a film containing barium oxide BaO, peroxide BaO 2 .
Reacts vigorously with water:
Va + 2H 2 O \u003d Ba (OH) 2 + H 2
When heated, it interacts with nitrogen (cm. NITROGEN) with the formation of nitride Ba 3 N 2:
Ba + N 2 \u003d Ba 3 N 2
In a stream of hydrogen (cm. HYDROGEN) when heated, barium forms a hydride BaH 2. With carbon, barium forms BaC 2 carbide. With halogens (cm. HALOGENS) barium forms halides:
Ba + Cl 2 \u003d BaCl 2,
Possible interaction with sulfur (cm. SULFUR) and other nonmetals.
BaO is the basic oxide. It reacts with water to form barium hydroxide:
BaO + H 2 O \u003d Ba (OH) 2
When interacting with acidic oxides, BaO forms salts:
BaO + CO 2 \u003d BaCO 3
The basic hydroxide Ba (OH) 2 is slightly soluble in water, has alkaline properties.
Ba 2+ ions are colorless. Chloride, bromide, iodide, barium nitrate are highly soluble in water. Insoluble carbonate, sulfate, average barium orthophosphate. Barium sulfate BaSO 4 is insoluble in water and acids. Therefore, the formation of a white cheesy precipitate BaSO 4 is qualitative reaction to Ba 2+ ions and sulfate ions.
BaSO 4 dissolves in a hot solution of concentrated H 2 SO 4, forming acid sulfate:
BaSO 4 + H 2 SO 4 \u003d 2Ba (HSO 4) 2
Ba 2+ ions color the flame yellow-green.
Application
An alloy of Ba with Al is the basis of getters (getters). BaSO 4 is a component of white paints, it is added during the dressing of some types of paper, used in aluminum smelting, in medicine - for x-ray examination.
Barium compounds are used in glass production, in the manufacture of signal rockets.
Barium titanate BaTiO 3 is a component of piezoelectric elements, small capacitors, used in laser technology.
Physiological action
Barium compounds are toxic, MPC in the air is 0.5 mg/m 3 .

encyclopedic Dictionary. 2009 .

See what "barium" is in other dictionaries:

barium- hydrotogy. chem. Suda eritin, tyssiz crystals zat (KSE, 2, 167). Barium carbonates. chem. Tұz zhane nitrogen kyshkyldarynda onay eritin, tүssіz crystal. B a r i y k a r b o n a t y - baridyn өte manyzdy kosylystarynyn biri (KSE, 2, 167). Barium sulfates... Kazakh tilinin tusindirme sozdigі

- (Latin barium, from Greek barys heavy). A yellowish metal, so named because it combines with other metals to form heavy compounds. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. BARIUM lat. barium, from Greek ... ... Dictionary of foreign words of the Russian language

Ba (lat. Baryum, from Greek. barys heavy * a. barium; n. Barium; f. barium; and. bario), chem. element of the main subgroup 11 of the periodic group. Mendeleev's systems of elements, at. n. 56, at. m. 137.33. Natural B. consists of a mixture of seven stable ... Geological Encyclopedia

- (from Greek barys heavy; lat. Barium), Ba, chem. element II group periodic. systems of elements of the subgroup of alkaline earth elements, at. number 56, at. weight 137.33. Natural B. contains 7 stable isotopes, among which 138Ba predominates ... ... Physical Encyclopedia

BARIUM- (from Greek barys heavy), diatomic metal, at. V. 137.37, chem. designation Ba, occurs in nature only in the form of salts, ch. arr., in the form of sulfate salt (heavy spar) and carbonate salt (witherite); in small amounts of salt B. ... ... Big Medical Encyclopedia

- (Barium), Ba, a chemical element of group II of the periodic system, atomic number 56, atomic mass 137.33; belongs to the alkaline earth metals. Discovered by the Swedish chemist K. Scheele in 1774, received by G. Davy in 1808 ... Modern Encyclopedia

- (lat. Barium) Ba, a chemical element of group II of the periodic system, atomic number 56, atomic mass 137.33, belongs to the alkaline earth metals. Name from Greek. barys is heavy. Silvery white soft metal; density 3.78 g/cm³, tpl… … Big Encyclopedic Dictionary barium - noun, number of synonyms: 2 metal (86) element (159) ASIS synonym dictionary. V.N. Trishin. 2013 ... Synonym dictionary