SPECTRUM

Chemical Fact Sheet

Barium

Chemical Abstract Number (CAS #) 7440-39-3
Synonyms Bario-(Spanish);Baryum-(French)
Analytical Methods 200.7 - 200.8 - 6010 - 6020
Molecular Formula Ba

Synopsis

Barium - (Gr. barys, heavy), Ba; at. wt. 137.327(7), at. no. 56 ; m.p. 727 deg C; b.p. 1897 deg C; sp.gr 3.5 (20 deg C); valence 2. Baryta was distinguished from lime by Scheele in 1774; the element was discovered by Sir Humphrey Davy in 1808. It is found only in combination with other elements, chiefly in barite or heavy spar (sulfate) and witherite (carbonate) and is prepared by electrolysis of the chloride. Barium is a metallic element, soft, and when pure is silvery white like lead; it belongs to the alkaline earth group, resembling calcium chemically. The metal oxidizes very easily and should be kept under petroleum or other suitable oxygen-free liquids to exclude air. It is decomposed by water or alcohol. The metal is used as a "getter" in vacuum tubes. The most important compounds are the peroxide (BaO2), chloride, sulfate, carbonate, nitrate, and chlorate. Lithopone, a pigment containing barium sulfate and zinc sulfide, has good covering power, and does not darken in the presence of sulfides. The sulfate, as permanent white or blanc fixe, is also used in paint, in X-ray diagnostic work, and in glassmaking. Barite is extensively used as a weighting agent in oilwell drilling fluids, and also in making rubber. The carbonate has been used as a rat poison, while the nitrate and chlorate give colors in pyrotechny. The impure sulfide phosphoresces after exposure to the light. The compounds and the metal are not expensive. Barium metal (99.7+% pure) costs about 40 ct./gm. All barium compounds that are water or acid soluble are poisonous. Naturally occurring barium is a mixture of seven stable isotopes. Thirty nine other radioactive isotopes and isomers are known to exist.
Use CARRIER FOR RADIUM; ALLOYS OF BARIUM WITH ALUMINUM OR MAGNESIUM ARE USED AS GETTERS IN ELECTRONIC TUBES; EMISSIONS FROM (140)BA CONTRIBUTE TO FISSION PRODUCTS OF URANIUM RODS. EMISSIONS FROM (133)BARIUM & (137M)BA ARE USED AS STD IN GAMMA-SPECTROMETRY. DEOXIDIZER FOR COPPER; FRAY'S METAL; LUBRICANT FOR ANODE ROTORS IN X-RAY TUBES; SPARK-PLUG ALLOYS. USED IN PAINTS, SOAP, PAPER & RUBBER, & IN MFR OF CERAMICS & GLASS Used as a component in various proprietary nodularizing and deoxidizing alloys USED EXTENSIVELY IN MANUFACTURE OF ALLOYS FOR SUCH PRODUCTS AS NICKEL BARIUM PARTS USED IN IGNITION EQUIPMENT FOR AUTOMOBILES & IN MANUFACTURE OF LITHOPONE, GLASS, CERAMICS, & TELEVISION PICTURE TUBES. AS A LOADER FOR PAPER, SOAP, RUBBER, & LINOLEUM; IN RADIO INDUSTRY FOR CLEANING UP LAST TRACES OF GAS IN VACUUM TUBES. As heat stabilizer for plastics. The largest end use of barium is as a "getter" to remove the last traces of gases from vacuum and television picture tubes. It is also used to improve performance of lead alloy grids of acid batteries, as a component of grey and ductile irons, and in the manufacture of steel, copper and other metals.
Apparent Color YELLOWISH-WHITE, SLIGHTLY LUSTROUS LUMPS; BODY-CENTERED CUBIC STRUCTURE;SILVER-WHITE
Boiling Point 1640 DEG C
Melting Point 725 DEG C
Molecular Weight 137.33
Density 3.51 AT 20 DEG C

Chemical and

Physical Properties

SOMEWHAT MALLEABLE; ELECTROMOTIVE FORCE (AQ) BARIUM(2+)/BARIUM= -2.91 VOLTS GIVES GREEN COLOR IN FLAME IT HAS A DISTINCTIVE PROPERTY OF ABSORBING GASES The isotopes 130, 132, 134, 135, 136, 137, and 138 are known. Alkaline-earth element of atomic number 56, Group IIA of Periodic Table; extrudable and machinable NATURALLY OCCURRING BARIUM IS A MIXTURE OF SEVEN STABLE ISOTOPES. THIRTEEN OTHER RADIOACTIVE ISOTOPES ARE KNOWN TO EXIST.

Environmental Fate

Barium metal does not occur free in nature. IT OCCURS IN ZINC OR IRON ORES. THE EARTH'S CRUST CONTAINS 450 PPM & SEAWATER CONTAINS ABOUT 0.03 PPM. Barium is emitted into the atmosphere mainly by the industrial processes involved in the mining, refining, and production of barium and barium based chemicals and as a result of combustion of coal and oil. Background levels for soil range from 100-3000 ppm barium. Ingestion or inhalation of dust or fume, skin or eye contact. Small numbers of people are known to be consuming well waters in Illinois, Kentucky, Pennsylvania, & New Mexico that are at, or exceed by 10 times, the standard for barium. AVG DAILY BARIUM INTAKE OF HUMAN ADULT IS ABOUT 1.3 MG (0.65-1.7 MG) In an American hospital diet, the avg daily intake of barium was estimated as 375 ug, while in the diet of the general population it may be as high as 1.33 mg. Estimated typical dietary barium intake originated 25% from milk, 25% from flour, 25% from potatoes, and 25% from misc high barium foods consumed in minor quantities, esp nuts. Normal levels for barium in various organs of unexposed persons have been published. Total amt in skeleton of a 70 kg American adult was estimated at 2 ug/g or about 90% of total body barium (Ba). Other organs with measurable levels incl eye (330 ng/g), lungs (160 ng/g), connective tissue (125 ng/g), skin (50 ng/g), adipose tissue (36 ng/g). In other internal organs, barium concn were slight. Among various parts of the eye, choroid had highest level, reaching 10 ug/g in man. Normal human blood contains 0.08-0.4 mg Ba/l; most or all is in the plasma fraction. Avg values are found: Bone 4.1-29 ug Ba/g; blood 41-95 ug Ba/g; kidney 1.3-20 ug Ba/g; liver 0.2-10 ug Ba/g; spleen 0.6-12 ug Ba/g. Assuming an avg of 70 kg as human body wt, the barium content has been estimated to be 16 mg. HUMAN ADULT BODY CONTAINS ABOUT 22 MG BARIUM, 66% OF IT PRESENT IN BONES. Dental enamel of the first bicuspids of humans less than 20 years of age was analyzed for 66 minor inorganic elements by spark source mass spectroscopy. Teeth were from 24 communities located in 16 states in the USA. Mean barium concentration was 4.2 + or - 0.60 ug/g (mg/kg) dry weight. Total body burden: 22 mg barium (90% in bone); levels in bone and aorta incr with age. Kidney: 0.04-1.0 mg Ba/kg; Liver: 0.04-1.0 mg Ba/kg; Muscle: 0.09 mg Ba/kg; Bone: 3-70 mg Ba/kg; Hair: 0.55-4.0 mg Ba/kg; Nails: 7.5 mg Ba/kg; iris (eye): 206-1100 mg Ba/kg (possible function in vision); Blood: 0.068 mg Ba/l. Based on autopsy data, barium levels in human bone are relatively constant and do not appear to increase with age, ranging from an average value of 7.0 ppm in bone at age 0 to 3 months to an average of 8.5 ppm at age 33 to 74 years.

Disposal

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

Atmosphere

In urban air, the avg concn of barium was 5 (range 0-1500) ng/cu m in 18 USA cities.


DISCLAIMER - Please Read

Return to :

Alphabetical List of Compounds
List of Compounds by CAS Number
List of Services
Spectrum Laboratories Homepage