Barium oxide

Barium oxide
Other names	Barium monoxide Barium protoxide Calcined baryta
Identifiers
CAS number	[1304-28-5]
RTECS number	CQ9800000
Properties
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
Structure
Crystal structure	cubic
Coordination geometry	Octahedral
Hazards
MSDS	External MSDS
EU Index	056-002-00-7
EU classification	Harmful (Xn)
R-phrases	R20/22
S-phrases	(S2), S28
NFPA 704	0 3 2
Flash point	non-flammable
Related compounds
Other anions	Barium hydroxide Barium peroxide
Other cations	Calcium oxide Strontium oxide
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
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

Uses

Barium oxide is used as a coating for hot cathodes, and in cathode ray tubes. It is used in the production of certain kinds of glass such as optical crown glass. It replaced lead(II) oxide. Lead oxide was used to raise the refractive index, but it also raised the dispersive power. Barium oxide only raises the refractive index.^[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]

Preparation

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 also is dangerous to the environment. It is harmful especially to aquatic organisms^[5]

References

1. ^ [http://www.webelements.com/webelements/compounds/text/Ba/Ba1O1-1304285.html "Compounds of barium: barium (II) oxide"]. Web Elements. The University of Sheffield. 2007-01-26. http://www.webelements.com/webelements/compounds/text/Ba/Ba1O1-1304285.html. Retrieved on 2007-02-22. 
2. ^ "Barium Oxide (chemical compound)". Encyclopædia Britanica. Encyclopædia Britanica. 2007. http://www.britannica.com/eb/topic-53368/barium-oxide. Retrieved on 2007-02-19. 
3. ^ Nield, Gerald; Washecheck, Paul; Yang, Kang (05-04). "United States Patent 4210764". http://www.freepatentsonline.com/4210764.html. 
4. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
5. ^ "Barium Oxide (ICSC)". IPCS. October 1999. http://www.inchem.org/documents/icsc/icsc/eics0778.htm. Retrieved on 2007-02-19. 

External links

• International Chemical Safety Card 0778