Barium oxide

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Barium oxide
NaCl polyhedra.png
Barium oxide.JPG
Other names
Barium monoxide
Barium protoxide
Calcined baryta
3D model (JSmol)
ECHA InfoCard 100.013.753
PubChem CID
RTECS number CQ9800000
Molar mass 153.326 g/mol
Appearancewhite solid
Density 5.72 g/cm3, solid
Melting point 1,923 °C (3,493 °F; 2,196 K)
Boiling point ~ 2,000 °C (3,630 °F; 2,270 K)
3.48 g/100 mL (20 °C)
90.8 g/100 mL (100 °C)
Reacts to form Ba(OH)2
Solubility soluble in ethanol, dilute mineral acids and alkalies; insoluble in acetone and liquid ammonia
-29.1·10−6 cm3/mol
cubic, cF8
Fm3m, No. 225
70 J·mol−1·K−1 [1]
−582 kJ·mol−1 [1]
Safety data sheet See: data page
Hazard X.svg Xn
R-phrases (outdated) R20/22
S-phrases (outdated) (S2), S28
NFPA 704
Flammability code 0: Will not burn. E.g. waterHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeBarium oxide
Flash point Non-flammable
Related compounds
Other anions
Barium hydroxide
Barium peroxide
Other cations
Calcium oxide
Strontium oxide
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Phase behaviour
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)
Infobox references

Barium oxide, BaO, is a white hygroscopic non-flammable compound. It has a cubic 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.

Chemical compound Substance composed of multiple elements

A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds. Two atoms of the same element bonded in a molecule do not form a chemical compound, since this would require two different elements.

Cubic crystal system lattice point group

In crystallography, the cubiccrystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.


It is prepared by heating barium carbonate with coke, carbon black or tar or by thermal decomposition of barium nitrate.[ citation needed ]

Barium carbonate chemical compound

Barium carbonate (BaCO3), also known as witherite, is a chemical compound used in rat poison, bricks, ceramic glazes and cement.

Coke (fuel) fuel

Coke is a grey, hard, and porous fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air — a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.

Carbon black Chemical compound

Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, or ethylene cracking tar. Carbon black is a form of paracrystalline carbon that has a high surface-area-to-volume ratio, albeit lower than that of activated carbon. It is dissimilar to soot in its much higher surface-area-to-volume ratio and significantly lower polycyclic aromatic hydrocarbon (PAH) content. However, carbon black is widely used as a model compound for diesel soot for diesel oxidation experiments. Carbon black is mainly used as a reinforcing filler in tires and other rubber products. In plastics, paints, and inks, carbon black is used as a color pigment.


Barium oxide is used as a coating for hot cathodes, for example, those in cathode ray tubes. It replaced lead(II) oxide in the production of certain kinds of glass such as optical crown glass. While lead oxide raised the refractive index, it also raised the dispersive power, which barium oxide does not alter. [2] Barium oxide also has use as an ethoxylation catalyst in the reaction of ethylene oxide and alcohols, which takes place between 150 and 200 °C. [3]

Hot cathode Type of electrode.

In vacuum tubes and gas-filled tubes, a hot cathode or thermionic cathode is a cathode electrode which is heated to make it emit electrons due to thermionic emission. This is in contrast to a cold cathode, which does not have a heating element. The heating element is usually an electrical filament heated by a separate electric current passing through it. Hot cathodes typically achieve much higher power density than cold cathodes, emitting significantly more electrons from the same surface area. Cold cathodes rely on field electron emission or secondary electron emission from positive ion bombardment, and do not require heating. There are two types of hot cathode. In a directly heated cathode, the filament is the cathode and emits the electrons. In an indirectly heated cathode, the filament or heater heats a separate metal cathode electrode which emits the electrons.

Lead(II) oxide chemical compound

Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula PbO. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components. It is an amphoteric oxide.

Crown glass (optics) Type of glass

Crown glass is a type of optical glass used in lenses and other optical components. It has relatively low refractive index (≈1.52) and low dispersion. Crown glass is produced from alkali-lime silicates containing approximately 10% potassium oxide and is one of the earliest low dispersion glasses.

It is also a source of pure oxygen through heat fluctuation. It readily oxidises to BaO2 by formation of a peroxide 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. [4]

Peroxide class of chemical compound based structurally off the extent to which it is oxidized

Peroxides are a group of compounds with the structure R−O−O−R. The O−O group in a peroxide is called the peroxide group or peroxo group. In contrast to oxide ions, the oxygen atoms in the peroxide ion have an oxidation state of −1.

An ion is an atom or molecule that has a net electrical charge. Since the charge of the electron is equal and opposite to that of the proton, the net charge of an ion is non-zero due to its total number of electrons being unequal to its total number of protons. A cation is a positively charged ion, with fewer electrons than protons, while an anion is negatively charged, with more electrons than protons. Because of their opposite electric charges, cations and anions attract each other and readily form ionic compounds.

The reaction was used as a large scale method to produce oxygen before the air separation became the dominant method in the beginning of the 20th century. The method was named after its inventors the Brin process. [5]

Air separation chemical process

An air separation plant separates atmospheric air into its primary components, typically nitrogen and oxygen, and sometimes also argon and other rare inert gases.

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.


Barium oxide is made by heating barium carbonate. It may also be prepared by thermal decomposition of barium nitrate. [6] Likewise, it is often formed through the decomposition of other barium salts. [7]

Barium nitrate chemical compound

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.

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 and diarrhea, 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. [8]

See also

Related Research Articles

Hydrogen peroxide is a chemical compound with the formula H
. In its pure form, it is a very pale blue, clear liquid, slightly more viscous than water. Hydrogen peroxide is the simplest peroxide. It is used as an oxidizer, bleaching agent, and antiseptic. Concentrated hydrogen peroxide, or "high-test peroxide", is a reactive oxygen species and has been used as a propellant in rocketry. Its chemistry is dominated by the nature of its unstable peroxide bond.

Potassium oxide chemical compound

Potassium oxide (K2O) or Kalium oxide is an ionic compound of potassium and oxygen. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive compound. Some materials of commerce, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to the chemical compound mixture K2O.

Manganese dioxide chemical compound

Manganese(IV) oxide is the inorganic compound with the formula MnO
. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
is for dry-cell batteries, such as the alkaline battery and the zinc-carbon battery. MnO
is also used as a pigment and as a precursor to other manganese compounds, such as KMnO
. It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO
in the α polymorph can incorporate a variety of atoms in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
as a possible cathode for lithium ion batteries.

Mercury(II) oxide chemical compound

Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, has a formula of HgO. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is very rarely found.

Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion.

Lead dioxide chemical compound

Lead(IV) oxide, commonly called lead dioxide, plumbic oxide or anhydrous plumbic acid (sometimes wrongly called lead peroxide), is a chemical compound with the formula PbO2. It is an oxide where lead is in an oxidation state of +4; bond type is predominantly covalent. It is an odorless dark-brown crystalline powder which is nearly insoluble in water. It exists in two crystalline forms. The alpha phase has orthorhombic symmetry; it was first synthesized in 1941 and was identified in nature as a rare mineral scrutinyite in 1988. The more common tetragonal beta phase was first identified as the mineral plattnerite around 1845 and later produced synthetically. Lead dioxide is a strong oxidizing agent which is used in the manufacture of matches, pyrotechnics, dyes and other chemicals. It also has several important applications in electrochemistry, in particular as the negative plate (cathode) of lead acid batteries.

Copper chromite is an inorganic compound with the formula Cu2Cr2O5 which is used to catalyze reactions in organic synthesis.

Uranate any chemical compound having an oxyanion with at least one atom of uranium

A uranate is a ternary oxide involving the element uranium in one of the oxidation states 4, 5 or 6. A typical chemical formula is MxUyOz, where M represents a cation. The uranium atom in uranates(VI) has two short collinear U–O bonds and either four or six more next nearest oxygen atoms. The structures are infinite lattice structures with the uranium atoms linked by bridging oxygen atoms.

Zinc nitrate chemical compound

Zinc nitrate is an inorganic chemical compound with the formula Zn(NO3)2. This white, crystalline solid is highly deliquescent and is typically encountered as a hexahydrate Zn(NO3)2•6H2O. It is soluble in both water and alcohol.

Samarium(III) oxide chemical compound

Samarium(III) oxide (Sm2O3) is a chemical compound. Samarium oxide readily forms on the surface of samarium metal under humid conditions or temperatures in excess of 150°C in dry air. Similar to the metal, iron, this oxide layer spalls off the surface of the metal, exposing more metal to continue the reaction. The oxide is commonly white to off yellow in color and is often encountered as a highly fine dust like powder.

Barium peroxide chemical compound

Barium peroxide is the inorganic compound with the formula BaO2. This white solid (gray when impure) is one of the most common inorganic peroxides, and it was the first peroxide compound discovered. Being an oxidizer and giving a vivid green colour upon ignition (as do all barium compounds), it finds some use in fireworks; historically, it was also used as a precursor for hydrogen peroxide.

Barium chlorate chemical compound

Barium chlorate, Ba(ClO3)2, is a white crystalline solid, the barium salt of chloric acid. It is an irritant and toxic, as are all soluble barium compounds. It is sometimes used in pyrotechnics to produce a green color. It also finds use in the production of chloric acid.

Barium ferrate chemical compound

Barium ferrate is the chemical compound of formula BaFeO4. This is a rare compound containing iron in the +6 oxidation state. The ferrate(VI) ion has two unpaired electrons, making it paramagnetic. It is isostructural with BaSO4, and contains the tetrahedral [FeO4]2− anion.

The lithium–air battery (Li–air) is a metal–air electrochemical cell or battery chemistry that uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow.

Barium perchlorate is a powerful oxidizing agent, with the formula Ba(ClO4)2. It is used in the pyrotechnic industry.

Metal peroxide

Metal peroxides are metal-containing compounds with ionically- or covalently-bonded peroxide (O2−
) groups. This large family of compounds can be divided into ionic and covalent peroxide. The first class mostly contains the peroxides of the alkali and alkaline earth metals whereas the covalent peroxides are represented by such compounds as hydrogen peroxide and peroxymonosulfuric acid (H2SO5). In contrast to the purely ionic character of alkali metal peroxides, peroxides of transition metals have a more covalent character.

Praseodymium (III,IV) oxide is the inorganic compound with the formula Pr6O11 that is insoluble in water. It has a cubic fluorite structure. It is the most stable form of praseodymium oxide at ambient temperature and pressure.


  1. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN   978-0-618-94690-7.
  2. "Barium Oxide (chemical compound)". Encyclopædia Britannica. Encyclopædia Britannica. 2007. Retrieved 2007-02-19.
  3. Nield, Gerald; Washecheck, Paul; Yang, Kang (1980-07-01). "United States Patent 4210764" . Retrieved 2007-02-20.
  4. S.C. Middleburgh, K.P.D. Lagerlof, R.W. Grimes - Accommodation of Excess Oxygen in Group II Oxides
  5. Jensen, William B. (2009). "The Origin of the Brin Process for the Manufacture of Oxygen". Journal of Chemical Education. 86 (11): 1266. Bibcode:2009JChEd..86.1266J. doi:10.1021/ed086p1266.
  6. Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN   0-07-049439-8
  7. "Compounds of barium: barium (II) oxide". Web Elements. The University of Sheffield. 2007-01-26. Retrieved 2007-02-22.
  8. "Barium Oxide (ICSC)". IPCS. October 1999. Archived from the original on 26 February 2007. Retrieved 2007-02-19.