Lightweight heavyweight. So you can imagine barium. His name is translated from Greek as “heavy.” Compared to other alkaline earth elements, the substance is really heavy. In a “battle” with metals from other groups, as a rule, it loses.
The name of barium is associated with the history of its discovery. In the 17th century, the idea of extracting from waste materials was relevant. Bolognese shoemaker Casciarolo found an exceptionally heavy stone. Gold, as you know, is not a light metal. So the man suspected his presence in the cobblestones.
It was not possible to identify the jewel. But, after calcination, it began to glow red. The phenomenon attracted the attention of chemist Karl Scheele. He established the presence of a new element in the rock - “heavy earth”. When Humphry Davy from England allocated this “land” in 1808, it turned out to be easy. But they didn’t change the name.
Chemical and physical properties of barium
Nuclear mass of barium equal to 137 grams per mole. The metal is not only light, but also soft. Hardness does not exceed 3 points. The material is malleable and slightly viscous. The element density is about 3.7 grams per cubic centimeter. If contaminants are present, barium becomes brittle.
The color of the element is silver-gray. But green is considered the hallmark of barium. It manifests itself in a reaction characteristic of the 56th substance. It involves elements, for example, barium sulfate.
If you immerse a glass rod in it and bring it to the burner, a green flame will flare up. This way you can determine the presence of even negligible impurities of heavy metal.
Barium is a substance with a cubic lattice. It can be seen not only in laboratory conditions. The metal is found in its pure form and in nature. There are 2 known modifications of the element. One of them is stable up to 365 degrees Celsius, the other - from 375 to 710. Barium boils at a temperature of 1696 degrees Celsius.
Several radioactive isotopes of the metal have been synthesized. Barium formula with an atomic mass of 140 - the result of the decay of thorium, plutonium and uranium. The isotope is extracted by chromatography, that is, it is absorbed based on the color of the substance.
Barium 133 is formed during the irradiation of cesium. It is exposed to the nuclei of one of the isotopes of hydrogen - deuterons. The radioactive form of the alkaline earth metal released in this case decays in a little more than 3 days. The cycle of 140 barium is longer, only the half-life takes 13.5 days.
Like all alkaline earth metals, barium is chemically active. In the group it is listed in the middle, ahead of, for example, and. The latter are stored in air. This won't work with barium. The 56th element is placed under paraffin oil or petroleum ether.
Barium interaction with oxygen leads to loss of shine. Afterwards, the material turns yellow, brown and, ultimately, becomes gray. This is what it looks like barium oxide- the result of its destruction in the air. If the atmosphere is heated, the 56th metal in it will explode.
The interaction of an element with water is the reverse reaction with oxygen. Here the liquid is already decomposing. The process is possible only upon contact with pure metal. After the reaction it goes into barium hydroxide.
If you initially place not a native element in water, but its salts, nothing will happen. Barium chloride, and not only, are insoluble in H 2 O, they actively interact only with acids.
Barium Reacts easily with hydrogen. The only condition is heating. A metal hydride is formed. When heated, the reaction also occurs with ammonia. The result is a nitride. It can turn into cyanide if you continue to raise the temperature.
Barium solution blue - the result of interaction with the same ammonia, but in liquid form. Ammonia is separated from the mixture. It has a golden color and the substance decomposes easily.
Just add a catalyst and you'll get barium amide. True, it is used only as a reagent. What is the use of other compounds of the metal and itself?
Applications of barium
Since pure metal requires special storage techniques, it is used infrequently. Vacuum technology specialists are ready to turn a blind eye to the inconvenience of the element. Very good barium absorbs residual gases, that is, serves as a getter.
Metal is also used as a cleaner in the production of some and. Here the element absorbs not only gases, but also impurities, and also deoxidizes mixtures.
As a component of alloys, element 56 is used in combination with lead. The mixture is used for the production of bearings. Barium alloys, also displace the previously used printing compounds made of lead and antimony. Alkaline earth metal strengthens the alloy better.
Alloy c is a raw material for the manufacture of spark plug electrodes. They are needed in internal combustion engines and radio tubes. This ends the use of pure barium. Metal connections come into play.
A heavy stone once found in Bolon is a famous dye. According to its chemical composition, the rock is barium sulfate and belongs to the class. The raw materials are crushed and added to lithoponium. This white paint is known for its covering power.
The photo shows a lamp for the production of which barium is used
Barium rock is also present in expensive varieties, for example, intended for printing money. Barium sulfate makes banknotes heavier, making them denser and whiter.
Interestingly, Bolognese stone was initially used illegally in the dyeing industry. Lead white was diluted with a cheap component. The quality of the product decreased, but entrepreneurs got richer. In modern dyes barium spar– an additive that improves rather than worsens their parameters.
Barium precipitation, including the sulfuric acid form, are also used in medicine. Spar blocks X-rays. Barium sulfate is added to porridge and given to a patient with suspected gastrointestinal diseases. After this, the X-ray results are easier to interpret.
Barium equations indicate the ability to absorb not only X-rays, but also gamma rays. So, compounds of element 56 protect many nuclear reactors.
Barium carbonate needed for making glass melt. Barium nitrate– composite. Barium hydroxide solution Effectively cleanses animal fats and vegetable oils. Used as poison barium chloride solution.
In the photo, fireworks are another industry that uses the element barium
From the 56th metal, rhodizonate is also obtained sodium Barium They are even used for injections into the Sphinx statue. The sand sculpture is destroyed. The heavy metal helps strengthen the structure.
Barium mining
Barium metal obtained in several ways. They are united by the atmosphere. The reactions are carried out in a vacuum due to the violent interaction of the 56th element with oxygen.
The metallothermic reduction method is applied to barium oxide and chloride. The element is isolated from the latter compound using calcium carbide. Aluminum powder works with oxide. Requires heating up to 1200 degrees Celsius.
From the hydride and nitride of the 56th element it is also possible to isolate pure barium. Potassium obtained in a similar way, that is, not by reduction, but by means of thermal decomposition.
The process takes place in sealed capsules and or porcelain. Electrolysis is also used. It is suitable for working with molten barium chloride. The cathode is mercury.
Barium price
To metal barium prices negotiable on the market. The product is specific and rarely requested. The element is usually sold by chemical laboratories and metallurgical enterprises. The cost of metal connections is no secret.
Barium chloride, for example, costs 50-70 rubles per kilogram. Baryte sand You can also buy it for 10 rubles per 1000 grams. A kilogram of hydroxide is estimated at approximately 80-90 rubles. For barium sulfate they ask for at least 50 rubles, usually about a hundred. For wholesale deliveries, the price tag is often reduced a little.
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. 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.
(first electron)
(according to Pauling)
body-centered
| Ba | 56 |
| 137,327 | |
| 6s 2 | |
| Barium | |
Barium- an element of the main subgroup of the second group, the sixth period of the periodic system of chemical elements, with atomic number 56. Denoted 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.
Barium 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.
It got its name from the Greek barys - “heavy”, since its oxide (BaO) was first characterized as having a large mass.
Being in nature
Rare barium minerals: celsian or barium feldspar (barium aluminosilicate), hyalophane (mixed barium and potassium aluminosilicate), nitrobarite (barium nitrate), etc.
Isotopes
Natural 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.
Receipt
The main raw material for barium production is barite concentrate (80-95% BaSO 4), which in turn is obtained by barite flotation. Barium sulfate is further reduced with coke or natural gas:
BaSO 4 + 4C = BaS + 4CO
BaSO 4 + 2CH 4 = BaS + 2C + 4H 2 O.
Next, the sulfide, when heated, is hydrolyzed to barium hydroxide Ba(OH) 2 or, under the influence of CO 2, is converted into insoluble barium carbonate BaCO 3, which is then converted into barium oxide BaO (calcination at 800 °C for Ba(OH)2 and over 1000 °C for BaCO 3):
BaS + 2H 2 O = Ba(OH) 2 + H 2 S
BaS + H 2 O + CO 2 = BaCO 3 + H 2 S
Ba(OH) 2 = BaO + H 2 O
BaCO 3 = BaO + CO 2
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.
Chemical properties
Ba 3 N 2 + 2CO = Ba(CN) 2 + 2BaO
Barium reduces the oxides, halides and sulfides of many metals to the corresponding metal.
Qualitative and quantitative analysis
Qualitatively in solutions, barium is detected by the precipitation of barium sulfate BaSO 4, distinguishable from the corresponding calcium sulfates and strontium sulfates by their extremely low solubility in inorganic acids.
Sodium rhodizonate releases a characteristic red-brown precipitate of barium rhodizonate from neutral barium salts. The reaction is very sensitive and specific, allowing the determination of 1 part of barium ions per 210,000 parts by mass of solution.
Barium compounds color the flame yellow-green (wavelength 455 and 493 nm).
Barium is quantified gravimetrically in the form of BaSO 4 or BaCrO 4 .
Application
Use as a getter material
Metal barium, often in an alloy with aluminum, is used as a gas absorber (getter) in high-vacuum electronic devices, and is also added together with zirconium to liquid metal coolants (alloys of sodium, potassium, rubidium, lithium, cesium) to reduce aggressiveness to pipelines, and in metallurgy.
Chemical current sources
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.
Prices
Prices for barium metal in ingots with a purity of 99.9% fluctuate around $30 per 1 kg.
Biological role
The biological role of barium has not been sufficiently studied. It is not included in the list of vital microelements. All soluble barium salts are highly poisonous.
DEFINITION
Barium- fifty-sixth element of the Periodic Table. Designation - Ba from the Latin "barium". Located in the sixth period, group IIA. Refers to metals. The nuclear charge is 56.
Barium occurs in nature mainly in the form of sulfates and carbonates, forming the minerals barite BaSO 4 and witherite BaCO 3 . The barium content in the earth's crust is 0.05% (mass), which is significantly less than the calcium content.
In the form of a simple substance, barium is a silvery-white metal (Fig. 1), which in air is covered with a yellowish film of products of interaction with the components of air. Barium is similar in hardness to lead. Density 3.76 g/cm3. Melting point 727 o C, boiling point 1640 o C. It has a body-centered crystal lattice.
Rice. 1. Barium. Appearance.
Atomic and molecular mass of barium
DEFINITION
Relative molecular weight of the substance(M r) is a number showing how many times the mass of a given molecule is greater than 1/12 the mass of a carbon atom, and relative atomic mass of an element(A r) - how many times the average mass of atoms of a chemical element is greater than 1/12 of the mass of a carbon atom.
Since in the free state barium exists in the form of monatomic Ba molecules, the values of its atomic and molecular masses coincide. They are equal to 137.327.
Barium isotopes
It is known that in nature barium can be found in the form of seven stable isotopes 130 Ba, 132 Ba, 134 Ba, 135 Ba, 136 Ba, 137 Ba and 138 Ba, of which 137 Ba is the most common (71.66%). Their mass numbers are 130, 132, 134, 135, 136, 137 and 138, respectively. The nucleus of an atom of the barium isotope 130 Ba contains fifty-six protons and seventy-four neutrons, and the remaining isotopes differ from it only in the number of neutrons.
There are artificial unstable isotopes of barium with mass numbers from 114 to 153, as well as ten isomeric states of nuclei, among which the longest-lived isotope 133 Ba with a half-life of 10.51 years.
Barium ions
At the outer energy level of the barium atom there are two electrons, which are valence:
1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 6 6s 2 .
As a result of chemical interaction, barium gives up its valence electrons, i.e. is their donor, and turns into a positively charged ion:
Ba 0 -2e → Ba 2+ .
Barium molecule and atom
In the free state, barium exists in the form of monoatomic Ba molecules. Here are some properties characterizing the barium atom and molecule:
Examples of problem solving
EXAMPLE 1