Barium sulfate

Barium sulfate

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ImageName = Chemical structure of barium sulfate
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ImageName1 = 3D model of barium sulfate
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CASNo = 7727-43-7
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ATCCode_suffix = BA01
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Formula = BaSO4
MolarMass = 233.43 g/mol
Appearance = white crystalline
Density = 4.5 g/cm3
MeltingPt = 1580°C
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Solubility = 0.00115 g/L (18°C)
SolubilityProduct = 1.08×10-10 (25°C)
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Bioavail = negligible orally
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Barium sulfate is a white crystalline solid with the chemical formula BaSO4. It is poorly soluble in water and other traditional solvents but is soluble in concentrated sulfuric acid. The mineral barite is composed largely of barium sulfate and is a common ore of barium.

Uses

Radiocontrast agent

Barium sulfate is frequently used clinically as a radiocontrast agent for X-ray imaging and other diagnostic procedures. It is most often used in imaging of the GI tract during what is colloquially known as a 'Barium meal'.

It is administered, orally or by enema, as a suspension of fine particles in an aqueous solution (often with sweetening agents added). Although barium is a heavy metal, and its water-soluble compounds are often highly toxic, the extremely low solubility of barium sulfate protects the patient from absorbing harmful amounts of the metal. Barium sulfate is also readily removed from the body, unlike Thorotrast, which it replaced. Due to the relatively high atomic number (Z = 56) of barium, its compounds absorb X-rays more strongly than compounds derived from lighter nuclei.

Pigment

Barium sulfate mixtures are used as white pigment for paints. The combination of barium sulfate and zinc sulfide (ZnS) is called lithopone. Barium sulfate itself is called blanc fixe. It replaced white lead due to the latter's toxicity.

Pyrotechnics

Barium sulfate is also used as a high temperature oxidizer in certain pyrotechnic formulas, as barium compounds emit a green colored light when burned. Barium nitrate is more common in green pyrotechnic formulas, as it contains an oxidizer while still producing green colored light.

Other uses

Barium sulfate is used as a filler in plastics and as a component of oil well drilling fluid to increase the density. It is used in Episal salt.

It is used in brake linings, anacoustic foams and powder coatings

Barium sulfate is also used during the procedure of the soil pH test. In this test it is used so that it precipitates out any particles (usually clay particles) which would otherwise 'cloud' solution preventing one from seeing the colour of the pH indicator i.e. the result of the test.

It is used in root canal filling.

In colorimetry barium sulfate is used as a near-perfect diffuser when measuring light sources.

In photography it is used as a coating for certain photographic papers.

In metal casting, the moulds used are often coated with barium sulphate in order to prevent the molten metal from bonding with the mould.

History

Barium sulfate is reduced to barium sulfide by carbon. The accidental discovery of this conversion many centuries ago led to the discovery of the first synthetic phosphor (Hollman and Wiberg, 2001). The sulfide, unlike the sulfate, is water soluble.

Etymology

Barium, 1808, Mod.L., from Gk. barys "heavy;" so called by its discoverer, British chemist Sir Humphrey Davy (1778-1829) because it was present in the mineral barytes "heavy spar," from Gk. barys "heavy" (see grave (adj.)).

References

* Holleman, A. F. and Wiberg, E. (2001) "Inorganic Chemistry", San Diego, CA : Academic Press, ISBN 0-12-352651-5


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Look at other dictionaries:

  • barium sulfate — n a colorless crystalline insoluble salt BaSO4 occurring in nature as barite and used medically chiefly as a radiopaque substance * * * [USP] BaSO4, an odorless fine white powder used as a contrast medium in radiography of the digestive tract.… …   Medical dictionary

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  • barium sulfate — bario sulfatas statusas T sritis chemija formulė BaSO₄ atitikmenys: angl. barium sulfate rus. барий сернокислый; бария сульфат ryšiai: sinonimas – bario tetraoksosulfatas …   Chemijos terminų aiškinamasis žodynas

  • Barium sulfate suspension — is barium sulfate (powder) turned into a liquid form by suspending it in a quick flowing drink to aid in CT scans of the gastrointestinal region.UseBarium sulfate suspensions are provided by a radiologist in advance of a CT scan to allow for… …   Wikipedia

  • barium sulfate — noun a white insoluble radiopaque powder used as a pigment • Syn: ↑barium sulphate, ↑blanc fixe • Hypernyms: ↑sulfate, ↑sulphate …   Useful english dictionary

  • barium sulfate — noun Date: 1866 a crystalline insoluble compound BaSO4 that is used especially as a pigment and extender, as a filler (as in fluids used in gas and oil drilling), and as a substance opaque to X rays in medical photography of the alimentary canal …   New Collegiate Dictionary

  • barium sulfate — Chem. a white, crystalline, water insoluble powder, BaSO4, used chiefly in the synthesis of pigments, as in paints and printing inks, and, because of its radiopacity, for x ray diagnosis in medicine. [1870 75] * * * …   Universalium

  • barium sulfate — bar′ium sul′fate n. chem. a white, crystalline, water insoluble powder, BaSO4, used chiefly in the synthesis of pigments and as a contrast medium in x ray diagnosis • Etymology: 1870–75 …   From formal English to slang

  • Barium — (pronEng|ˈbɛəriəm) is a chemical element. It has the symbol Ba, and atomic number 56. Barium is a soft silvery metallic alkaline earth metal. It is never found in nature in its pure form due to its reactivity with air. Its oxide is historically… …   Wikipedia

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