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Barium oxide
NaCl polyhedra.png
Other names Barium monoxide
Barium protoxide
Calcined baryta
CAS number 1304-28-5 Yes check.svgY
RTECS number CQ9800000
Molecular formula BaO
Molar mass 153.33 g/mol
Appearance white solid
Density 5.72 g/cm3, solid
Melting point

1923 °C

Boiling point

~2000 °C

Solubility in water 3.48 g/100 mL (20 °C)
90.8 g/100 mL (100 °C)
Solubility soluble in ethanol, dilute mineral acids and alkalies; insoluble in acetone and liquid ammonia
Crystal structure cubic, cF8
Space group Fm3m, No. 225
MSDS External MSDS
EU Index 056-002-00-7
EU classification Harmful (Xn)
R-phrases R20/22
S-phrases (S2), S28
NFPA 704
NFPA 704.svg
Flash point non-flammable
Related compounds
Other anions Barium hydroxide
Barium peroxide
Other cations Calcium oxide
Strontium oxide
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Barium oxide, BaO, is a white hygroscopic compound formed by the burning of barium in oxygen, although it is often formed through the decomposition of other barium salts.[1]

2Ba + O2 → 2BaO
BaCO3 → BaO + CO2

It transforms into barium hydroxide on contact with water.

BaO + H2O → Ba(OH)2



Barium oxide is used as a coating for hot cathodes, and 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]


Barium oxide is made by heating barium carbonate with coke, carbon black or tar. It may also be prepared by thermal decomposition of barium nitrate.[4]

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.[5]


  1. ^ [ "Compounds of barium: barium (II) oxide"]. Web Elements. The University of Sheffield. 2007-01-26. Retrieved 2007-02-22.  
  2. ^ "Barium Oxide (chemical compound)". Encyclopædia Britanica. Encyclopædia Britanica. 2007. Retrieved 2007-02-19.  
  3. ^ Nield, Gerald; Washecheck, Paul; Yang, Kang (05-04). "United States Patent 4210764". Retrieved 2007-02-20.  
  4. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
  5. ^ "Barium Oxide (ICSC)". IPCS. October 1999. Retrieved 2007-02-19.  

External links

Simple English

Barium oxide is a chemical compound. Its chemical formula is BaO. It contains barium and oxide ions.



Barium oxide is a white solid. It dissolves in water to make barium hydroxide. It reacts with acids to make barium salts.


Barium oxide is made by heating barium carbonate with carbon. This prevents barium peroxide from forming when it is heated. It can also be made by heating barium nitrate.


Barium oxide can be added to glass instead of lead(II) oxide. It is also used in cathode ray tubes. It can be used as a catalyst.


Barium oxide is very toxic when eaten.

See also

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