Barium is an element of the main subgroup of 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). The simple substance barium (CAS number: 7440-39-3) is a soft, malleable alkaline earth metal of a silvery-white color. Has high chemical activity.
Being in nature
Rare barium minerals: celsian or barium feldspar (barium aluminosilicate), hyalophane (mixed barium and potassium aluminosilicate), nitrobarite (barium nitrate), etc.
Obtaining Barium
The metal can be obtained in different ways, in particular by electrolysis of a molten mixture of barium chloride and calcium chloride. It is possible to obtain barium by reducing it from its oxide using an aluminothermic method. To do this, witherite is fired with coal and barium oxide is obtained:
BaCO 3 + C > BaO + 2CO.
Then the mixture of BaO with aluminum powder is heated in vacuum to 1250°C. Vapors of reduced barium condense in the cold parts of the tube in which the reaction takes place:
3BaO + 2Al > Al 2 O 3 + 3Ba.
It is interesting that barium peroxide BaO 2 is often included in the composition of ignition mixtures for aluminothermy.
Obtaining barium oxide by simple calcination of witherite is difficult: witherite decomposes only at temperatures above 1800°C. It is easier to obtain BaO by calcining barium nitrate Ba(NO 3) 2:
2Ba (NO 3) 2 > 2BaO + 4NO 2 + O 2.
Both electrolysis and aluminum reduction produce a soft (harder than lead, but softer than zinc) shiny white metal. It melts at 710°C, boils at 1638°C, and its density is 3.76 g/cm 3 . All this fully corresponds to the position of barium in the subgroup of alkaline earth metals.
Barium- an element of the main subgroup of 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. Has 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 the mercury evaporated when heated, it released 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 34 years later, Humphry Davy, having subjected wet barite earth to electrolysis, obtained a new element from it - barium. It should be noted that in the same 1808, somewhat earlier than Davy, Jene Jacob Berzelius and his colleagues obtained amalgams of calcium, strontium and barium. This is how the element barium appeared.
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 - significantly more than, say, lead, tin, copper or mercury. It is not found in the earth in its pure form: barium is active, it belongs to the subgroup of alkaline earth metals and, naturally, is bound quite tightly in minerals.
The main barium minerals 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. Barium salts are found in small concentrations in many mineral waters and sea water. The low content in this case is a plus, not a minus, because all barium salts, except sulfate, are poisonous.
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| Atom properties | |||
|---|---|---|---|
| Name, symbol, number |
Barium / Barium (Ba), 56 |
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| Atomic mass (molar mass) |
137.327(7)(g/mol) |
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| Electronic configuration | |||
| Atomic radius | |||
| Chemical properties | |||
| covalent radius | |||
| Ion radius | |||
| Electronegativity |
0.89 (Pauling scale) |
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| Electrode potential | |||
| Oxidation states | |||
| Ionization energy (first electron) |
502.5 (5.21) kJ/mol (eV) |
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| Thermodynamic properties of a simple substance | |||
| Density (at normal conditions) | |||
| Melting temperature | |||
| Boiling temperature | |||
| Ud. heat of fusion |
7.66 kJ/mol |
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| Ud. heat of vaporization |
142.0 kJ/mol |
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| Molar heat capacity |
28.1 J/(K mol) |
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| Molar volume |
39.0 cm³/mol |
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| Crystal lattice of a simple substance | |||
| Lattice structure |
cubic |
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| Lattice parameters | |||
| Other characteristics | |||
| Thermal conductivity |
(300 K) (18.4) W/(m K) |
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Barium is an element of the main subgroup of 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). The simple substance is a soft, malleable alkaline earth metal of a silvery-white color. Has high chemical activity.
History of the discovery of bariumBarium was discovered as the oxide BaO in 1774 by Karl Scheele. In 1808, the English chemist Humphry Davy obtained barium amalgam by electrolysis of wet barium hydroxide with a mercury cathode; After the mercury evaporated when heated, it released barium metal.
In 1774, the Swedish chemist Carl Wilhelm Scheele and his friend Johan Gottlieb Hahn investigated one of the heaviest minerals - heavy spar BaSO 4. They managed to isolate previously unknown “heavy earth,” which was later called barite (from the Greek βαρυς - heavy). And 34 years later, Humphry Davy, having subjected wet barite earth to electrolysis, obtained a new element from it - barium. It should be noted that in the same 1808, somewhat earlier than Davy, Jene Jacob Berzelius and his colleagues obtained amalgams of calcium, strontium and barium. This is how the element barium appeared.
Ancient alchemists calcined BaSO 4 with wood or charcoal and obtained phosphorescent “Bolognese gems”. But chemically these gems are not BaO, but barium sulfide BaS.
origin of name
It got its name from the Greek barys - "heavy", since its oxide (BaO) was characterized as having an unusually high density for such substances.
Finding barium in natureThe 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 BaSO 4 (more often called barite) and witherite BaCO3, named after the Englishman William Withering (1741 ... 1799), who discovered this mineral in 1782. Barium salts are found in a small concentration in 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.
Types of barium depositsBased on mineral associations, barite ores are divided into monomineral and complex. Complex complexes are divided into barite-sulfide (contain sulfides of lead, zinc, sometimes copper and iron pyrite, less often Sn, Ni, Au, Ag), barite-calcite (contain up to 75% calcite), iron-barite (contain magnetite, hematite, and in the upper zones goethite and hydrogoethite) and barite-fluorite (in addition to barite and fluorite, they usually contain quartz and calcite, and zinc, lead, copper and mercury sulfides are sometimes present in the form of small impurities).
From a practical point of view, hydrothermal vein monomineral, barite-sulfide and barite-fluorite deposits are of greatest interest. Some metasomatic strata deposits and eluvial placers are also of industrial importance. Sedimentary deposits, which are typical chemical sediments of water basins, are rare and do not play a significant role.
As a rule, barite ores contain other useful components (fluorite, galena, sphalerite, copper, gold in industrial concentrations), so they are used in combination.
Barium isotopesNatural barium consists of a mixture of seven stable isotopes: 130 Ba, 132 Ba, 134 Ba, 135 Ba, 136 Ba, 137 Ba, 138 Ba. The latter is the most common (71.66%). Radioactive isotopes of barium are also known, the most important of which is 140 Ba. It is formed by the decay of uranium, thorium and plutonium.
Obtaining bariumThe metal can be obtained in different ways, in particular by electrolysis of a molten mixture of barium chloride and calcium chloride. It is possible to obtain barium by reducing it from its oxide using an aluminothermic method. To do this, witherite is fired with coal and barium oxide is obtained:
BaCO 3 + C → BaO + 2CO.
Then the mixture of BaO with aluminum powder is heated in vacuum to 1250°C. Reduced barium vapor condenses in the cold parts of the pipe in which the reaction takes place:
3BaO + 2Al → Al 2 O 3 + 3Ba.
It is interesting that the composition of ignition mixtures for aluminothermy often includes barium peroxide BaO 2.
It is difficult to obtain barium oxide by simply calcining witherite: witherite decomposes only at temperatures above 1800°C. It is easier to obtain BaO by calcining barium nitrate Ba(NO 3) 2:
2Ba (NO 3) 2 → 2BaO + 4NO 2 + O 2.
Both electrolysis and reduction with aluminum produce a soft (harder than lead, but softer than zinc) shiny white metal. It melts at 710°C, boils at 1638°C, and its density is 3.76 g/cm 3 . All this fully corresponds to the position of barium in the subgroup of alkaline earth metals.
There are seven known natural isotopes of barium. The most common of these is barium-138; its more than 70%.
Barium is very active. It self-ignites on impact and easily decomposes water to form soluble barium oxide hydrate:
Ba + 2H 2 O → Ba (OH) 2 + H 2.
An aqueous solution of barium oxide hydrate is called barite water. This “water” is used in analytical chemistry for the determination of CO 2 in gas mixtures. But this is already from the story about the use of barium compounds. Metallic barium finds almost no practical use. It is introduced in extremely small quantities into bearing and printing alloys. An alloy of barium and nickel is used in radio tubes, pure barium is used only in vacuum technology as a getter (gas absorber).
Metal barium is obtained from the oxide by reduction with aluminum in a vacuum at 1200-1250°C:
4BaO + 2Al = 3Ba + BaAl 2 O 4.
Barium is purified by vacuum distillation or zone smelting.
Preparation of barium titanium. It is relatively easy to obtain. Witherite BaCO 3 at 700...800°C reacts with titanium dioxide TiO 2, the result is exactly what is needed:
BaCO 3 + TiO 2 → BaTiO 3 + CO 2.
Basic prom. The method for obtaining barium metal from BaO is its reduction with A1 powder: 4BaO + 2A1 -> 3Ba + BaO*A1 2 O 3. The process is carried out in a reactor at 1100-1200 °C in an Ar atmosphere or in a vacuum (the latter method is preferable). The molar ratio of BaO:A1 is (1.5-2):1. The reactor is placed in a furnace so that the temperature of its “cold part” (the resulting barium vapors are condensed in it) is about 520 ° C. By distillation in vacuum, barium is purified to an impurity content of less than 10 ~ 4% by weight, and when using zone melting - up to 10 ~ 6%.
Small amounts of barium are also obtained by the reduction of BaBeO 2 [synthesized by the fusion of Ba(OH) 2 and Be(OH) 2 ] at 1300°C with titanium, as well as the decomposition at 120°C of Ba(N 3) 2 formed during exchange p- tions of barium salts with NaN 3.
Ba acetate (OOСSN 3), - colorless. crystals; m.p. 490°C (with decomposition); dense 2.47 g/cm3; sol. in water (58.8 g per 100 g at 0°C). Below 25 °C, trihydrate crystallizes from aqueous solutions, at 25-41 °C - monohydrate, above 41 °C - anhydrous salt. Receive interaction. Ba(OH)2, BaCO3 or BaS with CH3CO2H. Used as a mordant when dyeing wool and calico.
Manganate(VI) BaMnO 4 - green crystals; does not decompose up to 1000°C. Obtained by calcination of a mixture of Ba(NO 3) 2 with MnO 2. A pigment (Cassel, or manganese green) commonly used for fresco painting.
Chromate(VI) BaСrO 4 - yellow crystals; m.p. 1380°C; - 1366.8 kJ/mol; sol. in non-org. k-tah, not sol. in water. Receive interaction. aqueous solutions of Ba(OH) 2 or BaS with alkali metal chromates(VI). Pigment (barite yellow) for ceramics. MPC 0.01 mg/m 3 (in terms of Cr0 3). Pyrconate BaZrO 3 - colorless. crystals; m.p. ~269°C; - 1762 kJ/mol; sol. in water and aqueous solutions of alkalis and NH 4 HCO 3, decomposes by strong inorg. to-tami. Receive interaction. ZrO 2 with BaO, Ba(OH) 2 or BaCO 3 when heated. Ba zirconate mixed with BaTiO 3 is a piezoelectric.
Bromide BaBr 2 - white crystals; m.p. 847°C; dense 4.79 g/cm3; -757 kJ/mol; well sol. in water, methanol, worse - in ethanol. Dihydrate crystallizes from aqueous solutions, turning into monohydrate at 75°C, into anhydrous salt - above 100°C. In aqueous solutions, interaction. with CO 2 and O 2 of air, forming BaCO 3 and Br 2. Get BaBr 2 interaction. aqueous solutions of Ba(OH) 2 or BaCO 3 with hydrobromic acid.
Iodide BaI 2 - colorless. crystals; m.p. 740°C (with decomposition); dense 5.15 g/cm3; . -607 kJ/mol; well sol. in water and ethanol. From hot water solutions, the dihydrate crystallizes (dehydrates at 150°C), below 30°C - the hexahydrate. Get BaI 2 interaction. aqueous solutions of Ba(OH) 2 or BaCO 3 with hydroiodic acid.
Physical properties of bariumBarium is a silvery-white malleable metal. If struck sharply, it breaks. There are two allotropic modifications of barium: α-Ba with a cubic body-centered lattice (parameter a = 0.501 nm) is stable up to 375 °C; β-Ba is stable above it.
Hardness on the mineralogical scale 1.25; Mohs scale 2.
Store barium metal in kerosene or under a layer of paraffin.
Chemical properties of bariumBarium is an alkaline earth metal. It oxidizes intensively in air, forming barium oxide BaO and barium nitride Ba 3 N 2 , and ignites with slight heating. Reacts vigorously with water, forming barium hydroxide Ba(OH) 2:
Ba + 2H 2 O = Ba(OH) 2 + H 2
Actively interacts with dilute acids. Many barium salts are insoluble or slightly soluble in water: barium sulfate BaSO 4, barium sulfite BaSO 3, barium carbonate BaCO 3, barium phosphate Ba 3 (PO 4) 2. Barium sulfide BaS, unlike calcium sulfide CaS, is highly soluble in water.
Nature Barium consists of seven stable isotopes since May. parts 130, 132, 134-137 and 138 (71.66%). The cross-section of thermal neutron capture is 1.17-10 28 m 2. External configuration electron shell 6s 2 ; oxidation state + 2, rarely + 1; ionization energy Ba°->Ba + ->Ba 2+ resp. 5.21140 and 10.0040 eV; Pauling electronegativity 0.9; atomic radius 0.221 nm, ionic radius Ba 2+ 0.149 nm (coordination number 6).
Reacts easily with halogens to form halides.
When heated with hydrogen, it forms barium hydride BaH 2 , which in turn forms the Li complex with lithium hydride LiH.
Reacts when heated with ammonia:
6Ba + 2NH 3 = 3BaH 2 + Ba 3 N 2
When heated, barium nitride Ba 3 N 2 reacts with CO, forming cyanide:
Ba 3 N 2 + 2CO = Ba(CN) 2 + 2BaO
With liquid ammonia it gives a dark blue solution, from which ammonia can be isolated, which has a golden sheen and easily decomposes with the elimination of NH 3. In the presence of a platinum catalyst, ammonia decomposes to form barium amide:
Ba(NH 2) 2 + 4NH 3 + H 2
Barium carbide BaC 2 can be obtained by heating BaO with coal in an arc furnace.
With phosphorus it forms phosphide Ba 3 P 2 .
Barium reduces the oxides, halides and sulfides of many metals to the corresponding metal.
Applications of bariumAn alloy of barium with A1 (Alba alloy, 56% Ba) is the basis of getters (gas absorbers). To obtain the getter itself, barium is evaporated from the alloy by high-frequency heating in an evacuated flask of the device; as a result, the so-called barium is formed on the cold parts of the flask. barium mirror (or diffuse coating during evaporation in a nitrogen environment). The active part of the vast majority of thermionic cathodes is BaO. Barium is also used as a deoxidizing agent for Cu and Pb, and as an additive to antifriction agents. alloys, ferrous and non-ferrous metals, as well as alloys from which printing fonts are made to increase their hardness. Alloys of barium with Ni are used for the manufacture of spark plug electrodes in internal engines. combustion and in radio tubes. 140 Va (T 1/2 12.8 days) is an isotopic indicator used in the study of barium compounds.
Barium metal, often alloyed with aluminum, is used as a getter in high-vacuum electronic devices.
Anti-corrosion materialBarium is added together with zirconium to liquid metal coolants (alloys of sodium, potassium, rubidium, lithium, cesium) to reduce the aggressiveness of the latter to pipelines and in metallurgy.
Barium fluoride is used in the form of single crystals in optics (lenses, prisms).
Barium peroxide is used for pyrotechnics and as an oxidizing agent. Barium nitrate and barium chlorate are used in pyrotechnics to color flames (green fire).
Barium chromate is used in the production of hydrogen and oxygen by thermochemical method (Oak Ridge cycle, USA).
Barium oxide, together with oxides of copper and rare earth metals, is used to synthesize superconducting ceramics operating at liquid nitrogen temperatures and above.
Barium oxide is used to melt a special type of glass - used to coat uranium rods. One of the widespread types of such glasses has the following composition - (phosphorus oxide - 61%, BaO - 32%, aluminum oxide - 1.5%, sodium oxide - 5.5%). Barium phosphate is also used in glass melting for the nuclear industry.
Barium fluoride is used in solid-state fluorine batteries as a component of the fluoride electrolyte.
Barium oxide is used in high-power copper oxide batteries as a component of the active mass (barium oxide-copper oxide).
Barium sulfate is used as a negative electrode active mass expander in the production of lead-acid batteries.
Barium carbonate BaCO 3 is added to the glass mass to increase the refractive index of the glass. Barium sulfate is used in the paper industry as a filler; The quality of paper is largely determined by its weight; barite BaSO 4 makes the paper heavier. This salt is necessarily included in all expensive types of paper. In addition, barium sulfate is widely used in the production of white paint lithopone - a product of the reaction of solutions of barium sulfide with zinc sulfate:
BaS + ZnSO 4 → BaSO 4 + ZnS.
Both salts, which are white, precipitate, leaving pure water in the solution.
When drilling deep oil and gas wells, a suspension of barium sulfate in water is used as a drilling fluid.
Another barium salt has important uses. This is barium titanate BaTiO 3 - one of the most important ferroelectrics (ferroelectrics are polarized on their own, without the influence of an external field. They stand out among dielectrics in the same way as ferromagnetic materials among conductors. The ability for such polarization is retained only at a certain temperature. Polarized ferroelectrics differ higher dielectric constant), which are considered very valuable electrical materials.
In 1944, this class was replenished with barium titanate, the ferroelectric properties of which were discovered by the Soviet physicist B.M. Vulom. The peculiarity of barium titanate is that it retains ferroelectric properties over a very wide temperature range - from close to absolute zero to +125°C.
Barium has also found application in medicine. Its sulfate salt is used in the diagnosis of gastric diseases. BaSO 4 is mixed with water and given to the patient to swallow. Barium sulfate is opaque to X-rays, and therefore those parts of the digestive tract through which the “barium porridge” passes remain dark on the screen. This way the doctor gets an idea of the shape of the stomach and intestines and determines the place where an ulcer may occur.
The effect of barium on the human body
Routes of entry into the body.
The main route of entry of barium into the human body is food. Thus, some marine inhabitants are capable of accumulating barium from the surrounding water, and in concentrations 7-100 (and for some marine plants up to 1000) times higher than its content in sea water. Some plants (soybeans and tomatoes, for example) are also capable of accumulating barium from the soil 2-20 times. However, in areas where barium concentrations in water are high, drinking water may also contribute to total barium consumption. The intake of barium from the air is insignificant.
Health hazard.
Scientific epidemiological studies conducted under the auspices of WHO did not confirm the relationship between mortality from cardiovascular diseases and barium levels in drinking water. In short-term studies in volunteers, no harmful effects on the cardiovascular system were detected at barium concentrations up to 10 mg/l. True, in experiments on rats, when the latter consumed water even with a low barium content, an increase in systolic blood pressure was observed. This indicates a potential risk of increased blood pressure in people with long-term consumption of water containing barium (USEPA has such data).
USEPA data also suggests that even a single drink of water containing barium levels well above the maximum permissible levels can lead to muscle weakness and abdominal pain. It is necessary, however, to take into account that the standard for barium established by the USEPA quality standard (2.0 mg/l) significantly exceeds the value recommended by WHO (0.7 mg/l). Russian sanitary standards set an even more stringent MPC value for barium in water - 0.1 mg/l. Technologies for removing water: ion exchange, reverse osmosis, electrodialysis.
Barium(lat. Baryum), Ba, chemical element of group II of the periodic system of Mendeleev, atomic number 56, atomic mass 137.34; silvery-white metal. It consists of a mixture of 7 stable isotopes, among which 138 Ba (71.66%) predominates. The nuclear fission of uranium and plutonium produces the radioactive isotope 140 Va, which is used as a radioactive tracer. Barium was discovered by the Swedish chemist K. Scheele (1774) in the form of BaO oxide, called “heavy earth”, or barite (from the Greek barys - heavy). Metallic Barium (in the form of an amalgam) was obtained by the English chemist G. Davy (1808) by electrolysis of wet Ba(OH)2 hydroxide with a mercury cathode. The content of Barium in the earth's crust is 0.05% by weight; it does not occur in nature in a free state. Of the Barium minerals, barite (heavy spar) BaSO 4 and the less common witherite BaCO 3 are of industrial importance.
Physical properties of Barium. The crystal lattice of Barium is cubic body-centered with a period a = 5.019 Å; density 3.76 g/cm 3, tnl 710°C, boiling point 1637-1640°C. Barium is a soft metal (harder than lead, but softer than zinc), its hardness on the mineralogical scale is 2.
Chemical properties of Barium. Barium belongs to the alkaline earth metals and is similar in chemical properties to calcium and strontium, surpassing them in activity. Barium reacts with most other elements, forming compounds in which it is usually 2-valent (there are 2 electrons in the outer electron shell of the Barium atom, its configuration is 6s 2). In air, Barium quickly oxidizes, forming a film of oxide (as well as peroxide and nitride Ba 3 N 2) on the surface. When heated, it ignites easily and burns with a yellow-green flame. Vigorously decomposes water, forming barium hydroxide: Ba + 2H 2 O = Ba(OH) 2 + H 2. Due to its chemical activity, Barium is stored under a layer of kerosene. BaO oxide - colorless crystals; in air it easily transforms into carbonate BaCO 3 and reacts vigorously with water, forming Ba(OH) 2. By heating BaO in air at 500 °C, BaO 2 peroxide is obtained, which decomposes at 700 °C into BaO and O 2. By heating the peroxide with oxygen under high pressure, higher peroxide BaO 4 is obtained - a yellow substance that decomposes at 50-60°C. Barium combines with halogens and sulfur, forming halides (for example, BaCl 2) and BaS sulfide, with hydrogen - BaH 2 hydride, which rapidly decomposes with water and acids. Of the commonly used Barium salts, barium chloride BaCl 2 and other halides, nitrate Ba(NO 3) 2, sulfide BaS, chlorate Ba(ClO 3) 2 are highly soluble, barium sulfate BaSO 4, barium carbonate BaCO 3 and chromate BaCrO 4 are sparingly soluble. .
Obtaining Barium. The main raw material for the production of Barium and its compounds is barite, which is reduced with coal in fiery furnaces: BaSO 4 + 4C = BaS + 4CO. The resulting soluble BaS is processed into other Barium salts. The main industrial method for producing metallic Barium is the thermal reduction of its oxide with aluminum powder: 4BaO + 2Al = 3Ba + BaO·Al 2 O 3 .
The mixture is heated at 1100-1200°C in vacuum (100 mn/m 2, 10 -3 mm Hg). Barium evaporates, depositing on the cold parts of the equipment. The process is carried out in periodic electric vacuum apparatuses, which make it possible to sequentially carry out the reduction, distillation, condensation and casting of the metal, obtaining a Barium ingot in one technological cycle. By double distillation in vacuum at 900°C, the metal is purified to an impurity content of less than 1·10 -4%.
Application of Barium. The practical use of barium metal is small. It is also limited by the fact that manipulation with pure Barium is difficult. Typically, Barium is either placed in a protective shell of another metal, or alloyed with some metal that gives Barium resistance. Sometimes metallic Barium is obtained directly in devices by placing tablets of a mixture of Barium and aluminum oxides into them and then carrying out thermal reduction in a vacuum. Barium, as well as its alloys with magnesium and aluminum, are used in high vacuum technology as an absorber of residual gases (getter). Barium is used in small quantities in the metallurgy of copper and lead for their deoxidation and purification from sulfur and gases. A small amount of Barium is added to some antifriction materials. Thus, the addition of Barium to lead noticeably increases the hardness of the alloy used for printing fonts. Barium-nickel alloys are used in the manufacture of electrodes for engine spark plugs and in radio tubes.
Barium compounds are widely used. BaO 2 peroxide is used to produce hydrogen peroxide, for bleaching silk and plant fibers, as a disinfectant and as one of the components of ignition mixtures in aluminothermy. BaS sulfide is used to remove hair from skins. Perchlorate Ba(ClO 4) 2 is one of the best desiccants. Nitrate Ba(NO 3) 2 is used in pyrotechnics. Colored barium salts - BaCrO 4 chromate (yellow) and BaMnO 4 manganate (green) - are good pigments for making paints. Barium platinocyanate Ba is used to cover screens when working with X-ray and radioactive radiation (bright yellow-green fluorescence is excited in the crystals of this salt under the influence of radiation). Barium titanate BaTiO 3 is one of the most important ferroelectrics. Since Barium absorbs X-rays and gamma radiation well, it is included in protective materials in X-ray facilities and nuclear reactors. Barium compounds are inert carriers for the extraction of radium from uranium ores. Insoluble Barium sulfate is non-toxic and is used as a contrast material for X-ray examination of the gastrointestinal tract. Barium carbonate is used to kill rodents.
Barium in the body. Barium is present in all plant organs; its content in plant ash depends on the amount of Barium in the soil and ranges from 0.06-0.2 to 3% (in barite deposits). The accumulation coefficient of Barium (Barium in ash / Barium in soil) for herbaceous plants is 0.2-6, for woody plants 1-30. Barium concentration is higher in roots and branches, less - in leaves; it increases as the shoots age. Barium (its soluble salts) is poisonous for animals, so herbs containing a lot of Barium (up to 2-30% in ash) cause poisoning in herbivores. Barium is deposited in the bones and in small amounts in other organs of animals. A dose of 0.2-0.5 g of barium chloride causes acute poisoning in humans, 0.8-0.9 g causes death.
Barium
BARIUM-I; m.[lat. Barium from Greek. barys - heavy].
1. Chemical element (Ba), a soft silvery-white reactive metal (used in technology, industry, medicine).
2. Razg. About the sulfate salt of this element (taken orally as a contrast agent for x-ray examination of the stomach, intestines, etc.). Drink a glass of barium.
◁ Barium, -aya, -oe (1 digit). B-salts. B. cathode.
barium(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 mp 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.
BARIUMBARIUM (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
. Oxidation state +2 (valence 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.
History of discovery
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) By calcining barite, I obtained BaO oxide. Only in 1808 the Englishman G. Davy (cm. DAVY Humphrey) used electrolysis to recover active metals from molten salts.
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 the production of 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 = BaCO 3 + Na 2 SO 4
The precipitate of acid-soluble barium carbonate is processed further.
The main industrial method for obtaining barium metal is its reduction with aluminum powder (cm. ALUMINUM) at 1000-1200 °C:
4BaO + 2Al = 3Ba + BaOAl 2 O 3
By reducing barite with coal or coke when heated, BaS is obtained:
BaSO 4 + 4С = BaS + 4СО
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 silver-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. It oxidizes intensively in air, forming a film containing barium oxide BaO and peroxide BaO 2 .
Reacts vigorously with water:
Ba + 2H 2 O = 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 = 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. HALOGEN) barium forms halides:
Ba + Cl 2 = BaCl 2,
Possible interaction with sulfur (cm. SULFUR) and other non-metals.
BaO is the basic oxide. It reacts with water to form barium hydroxide:
BaO + H 2 O = Ba(OH) 2
When interacting with acidic oxides, BaO forms salts:
BaO + CO 2 = BaCO 3
The basic hydroxide Ba(OH) 2 is slightly soluble in water and 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 curdled precipitate of BaSO 4 is a 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 = 2Ba(HSO 4) 2
Ba 2+ ions color the flame yellow-green.
Application
An alloy of Ba with Al is the basis of getters (gas absorbers). BaSO 4 is a component of white paints, it is added when making some types of paper, used in aluminum smelting, and in medicine - for x-ray examinations.
Barium compounds are used in glass production and in the manufacture of signal flares.
Barium titanate BaTiO 3 is a component of piezoelectric elements, small-sized capacitors, and is used in laser technology.
Physiological action
Barium compounds are toxic, the maximum permissible concentration in the air is 0.5 mg/m 3.
encyclopedic Dictionary. 2009 .
Synonyms:See what “barium” is in other dictionaries:
barium- hydrototys. chem. Suda eritin, tussiz kristaldy zat (KSE, 2, 167). Barium carbonates. chem. Thuz zhane nitrogen kyshkyldarynda onay eritin, thussiz crystal. B a r i c a r b o n a t s – barium ote manyzdy kosylystarynyn biri (KSE, 2, 167). Barium sulfates… Kazak tilinin tүsіndіrme сөздігі
- (Latin barium, from Greek barys heavy). A yellowish metal, so named because it produces heavy compounds when combined with other metals. 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; i. bario), chemical. element of the main subgroup 11 of the periodic group. Mendeleev's system 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, chemical. element of group II 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 the Greek barys heavy), diatomic metal, at. V. 137.37, chem. designation Ba, found in nature only in the form of salts, ch. arr., in the form of sulfate salt (heavy spar) and carbon dioxide salt (witherite); in small quantities of salt B.... ... Great Medical Encyclopedia
- (Barium), Ba, 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, obtained by G. Davy in 1808 ... Modern encyclopedia
- (lat. Barium) Ba, a chemical element of group II of the periodic table, atomic number 56, atomic weight 137.33, belongs to the alkaline earth metals. Name from Greek. Barys is heavy. Silvery white soft metal; density 3.78 g/cm³, tpl… … Large Encyclopedic Dictionary barium - noun, number of synonyms: 2 metal (86) element (159) ASIS Dictionary of Synonyms. V.N. Trishin. 2013… Synonym dictionary
