Barium oxide, also known as baria, is a white

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

non-flammable compound with the formula BaO. It has a

cubic Cubic may refer to: Science and mathematics * Cube (algebra), "cubic" measurement * Cube, a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex ** Cubic crystal system, a crystal system w ...

structure and is used in cathode ray tubes, crown glass, and catalysts. It is harmful to human skin and if swallowed in large quantity causes irritation. Excessive quantities of barium oxide may lead to death. It is prepared by heating barium carbonate with coke,

carbon black Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid ...

tar Tar is a dark brown or black viscosity, viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic matter, organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. ...

or by thermal decomposition of

barium nitrate Barium nitrate is the inorganic compound with the chemical formula Ba( NO3)2. It, like most barium salts, is colorless, toxic, and water-soluble. It burns with a green flame and is an oxidizer; the compound is commonly used in pyrotechnics. Man ...

Uses

Barium oxide is used as a coating for hot cathodes, for example, those in cathode ray tubes. It replaced

lead(II) oxide Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula lead, Pboxide, O. PbO occurs in two Polymorphism (materials science), polymorphs: litharge having a tetragonal crystal system, tetragonal crystal struc ...

in the production of certain kinds of glass such as optical crown glass. While lead oxide raised the

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, o ...

, it also raised the dispersive power, which barium oxide does not alter. Barium oxide also has use as an

ethoxylation Ethoxylation is a chemical reaction in which ethylene oxide adds to a substrate. It is the most widely practiced alkoxylation, which involves the addition of epoxides to substrates. In the usual application, alcohols and phenols are converted i ...

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

in the reaction of

ethylene oxide Ethylene oxide is an organic compound with the formula . It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sw ...

and alcohols, which takes place between 150 and 200 °C. It is also a source of pure oxygen through heat fluctuation. It readily oxidises to BaO₂ by formation of a

peroxide In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen ...

ion. The complete peroxidation of BaO to BaO₂ occurs at moderate temperatures but the increased entropy of the O₂ molecule at high temperatures means that BaO₂ decomposes to O₂ and BaO at 1175K. The reaction was used as a large scale method to produce oxygen before air separation became the dominant method in the beginning of the 20th century. The method was named the

Brin process Brin process is a now-obsolete industrial scale production process for oxygen. In this process barium oxide reacts at 500–600 °C with air to form barium peroxide which decomposes at above 800 °C by releasing oxygen. :2 BaO + O2 ⇌ 2 ...

, after its inventors.

Preparation

Barium oxide is made by heating barium carbonate at temperatures between 1000-1450 °C. It may also be prepared by thermal decomposition of

. Likewise, it is often formed through the decomposition of other barium salts. : 2Ba + O₂ → 2BaO : BaCO₃ → BaO + CO₂

Safety issues

Barium oxide is an irritant. If it contacts the skin or the eyes or is inhaled it causes pain and redness. However, it is more dangerous when ingested. It can cause

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

and

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin ...

, muscle paralysis, cardiac arrhythmia, and can cause death. If ingested, medical attention should be sought immediately. Barium oxide should not be released environmentally; it is harmful to

aquatic organisms Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

References

External links

International Chemical Safety Card 0778
{{oxygen compounds Barium compounds Oxides Rock salt crystal structure

Uses

Preparation

Safety issues

See also

References

External links