Barium . Chemical element, Ba, with atomic number 56 and atomic weight of 137.34. Barium occupies the eighteenth place in abundance in the earth’s crust, where it is found in 0.04%, intermediate value between calcium and strontium, the other alkaline earth metals. Barium compounds are obtained from mining and by conversion of two barium minerals. Barite, or barium sulfate, is the main mineral and contains 65.79% barium oxide. Witherite, sometimes called heavy spar, is barium carbonate and contains 72% barium oxide.
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- 1 History
- 2 Methods of obtaining
- 3 Abundance and natural state
- 4 Appearance
- 5 Crystal structure:
- 6 Other physical properties
- 7 Legislation
- 8 Other information
- 9 Sources
The metal was first isolated by Sir Humphry Davy in 1808 by electrolysis. In industry only small amounts are prepared by reduction of barium oxide with aluminum in large retorts. The metal is used in barium-nickel alloys for spark plug wires (barium increases the emitting capacity of the alloy) and in Frary metal, which is an alloy of lead, barium, and calcium, used in place of the metal. Babbitt because it can be molded.
Metal reacts with water more easily than strontium and calcium, but less than sodium; it oxidizes rapidly in air and forms a protective film that prevents further reaction, but in humid air it can ignite. The metal is chemically active enough to react with most nonmetals. Metal is ductile and malleable; freshly cut pieces have a glossy gray-white appearance. Soft barite (easy to grind) is preferred in the manufacture of barium compounds, but crystalline varieties can be used.
The raw barite is ground and mixed with charcoal powder. The mixture is calcined in a rotary reduction kiln; barium sulfate is reduced to barium sulfide or black ash. Black ash consists of about 70% barium sulfide and is treated with hot water to make a solution that serves as a starting material in the manufacture of many other compounds. Lipoton, a white powder consisting of 20% barium sulfate, 30% zinc sulfide, and less than 3% zinc oxide, is widely used as a pigment in white paints.
Fixed white is used in the manufacture of bright colorants. It is the best grade of barium sulfate for pigment in paints. Because of the high absorption of x-rays by barium, sulfate serves to coat the gastrointestinal tract in radiography, to increase contrast. Barium carbonate is useful in the ceramic industry to prevent efflorescence in earthenware clays.
It is also used as a glaze in pottery, in optical glass and as a poison for rats. Barium chloride is used in salt purification, in the manufacture of sodium chloride and hydroxide, as a flux in magnesium alloys, as a boiler water softener, and in medicinal preparations. Barium nitrate, also called barite saltpeter, is used in pyrotechnics and light signals (it produces green color) and a little less in medicinal preparations.
Barium oxide, known as barite, or calcined barite, is used as a drying agent in industry and in the hardening of steels. Barium peroxide is sometimes used as a bleaching agent. Barium chromate, lemon chromium or chromium yellow, is used in yellow pigments and safety phosphors.
Barium chlorate is used in pyrotechnics. Barium acetate and cyanide are used in industry as a chemical reagent and in metallurgy, respectively. Applications: It is used for the manufacture of paints, crystals and for explosives for fireworks and laboratory work.
Health Effects of Barium Naturally, the levels of Barium in the environment are very low. High amounts of Barium can only be found in soils and food, such as nuts, algae, fish and certain plants. The amount of Barium that is detected in food and water is generally not high enough to be of concern to health.
People at great risk from barium exposure with additional health effects are those who work in the barium industry. The biggest health risks they can suffer are caused by breathing air that contains Barium Sulfate or Barium Carbonate. Many hazardous waste landfills contain certain amounts of Barium. People who live near them are possibly exposed to harmful levels. Exposure can then be caused by breathing dust, eating soil or plants, or drinking water that is contaminated with Barium.
By skin contact it can also occur. Barium’s health effects depend on the solubility of the compounds. Barium compounds that dissolve in water can be harmful to human health. Taking a large amount of soluble barium can cause paralysis and in some cases even death.
Small amounts of water- soluble Barium can cause shortness of breath, increased blood pressure, arrhythmia, stomach pain, muscle weakness, changes in nerve reflexes, inflammation of the brain and liver. Damage to the kidneys and heart. Barium has not been shown to cause cancer in humans. There is no proof that Barium can cause infertility or birth defects.
Environmental Effects of Barium Barium is a silvery-white metal that can be found in the environment, where it exists naturally. It appears combined with other chemical elements, such as sulfur, carbon or oxygen. Barium compounds are used by the oil and gas industries to make drilling lubricants. Barium compounds are also used to make paints, bricks, tiles, glass, and rubbers.
Due to the extensive use of Barium in industries, Barium has been released into the environment in large quantities. As a result, Barium concentrations in air , water, and soil can be higher than concentrations that occur naturally in many places. Barium is released into the air by mines, the refining process, and during the production of Barium compounds. It can also enter the air during the combustion of coal and oils.
Some Barium compounds that are released during industrial processes dissolve easily in water and are found in lakes, rivers and streams. Due to their solubilities these Barium compounds can reach long distances from their emission points. When fish and other aquatic organisms absorb Barium compounds, the Barium will build up in their bodies.
Barium compounds that are persistent usually remain on the surface of the soil, or in the sediment of waters. Barium is found in most soils at low levels. These levels may be higher at hazardous waste landfills.
It is obtained by aluminothermic reduction of barium oxide under high vacuum. · By electrolysis of barium chloride.
Abundance and natural state
Due to its reactivity, it does not exist free in nature. Its most important compounds are the minerals barite (BaSO4) and witherite (BaCO3). It occupies the 14th position in abundance, constituting 0.05% of the earth’s crust. · ·
It is a silvery white metal, similar to calcium in appearance, soft and quite reactive. ·
Structure: Body centered cubic · ·
Other physical properties
It oxidizes rapidly in contact with air so it must be stored under oil and vigorously decomposes cold water releasing hydrogen . In flame tests it gives a characteristic green color.
According to RD 1138/1990 (BOE 226, dated 09/20/1990), the guide level for Ba in drinking water is 100 mg / L and there is no established maximum admissible concentration.
Metal reacts with water more easily than strontium and calcium, but less than sodium; it oxidizes rapidly in air and forms a protective film that prevents further reaction, but in humid air it can catch fire. The metal is chemically active enough to react with most nonmetals. Metal is ductile and malleable; freshly cut pieces have a glossy gray-white appearance