Barium oxide

Barium oxide, BaO, is a white hygroscopic non-flammable compound. It has a cubical structure. It is used in cathode ray tubes, making crown glass. 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 or tar or by thermal decomposition of Barium nitrate.

Uses

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. 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.

It is also a source of pure oxygen through heat fluctuation. It readily oxidises to BaO_1+x 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.

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. Likewise, it is often formed through the decomposition of other barium salts.

2Ba + O₂ â†' 2BaO

BaCO₃ â†' 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.

See Also

• Brin process

References

1. ^ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X. 
2. ^ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X. 
3. ^ "Barium Oxide (chemical compound)". Encyclopædia Britanica. Encyclopædia Britanica. 2007. Retrieved 2007-02-19. 
4. ^ Nield, Gerald; Washecheck, Paul; Yang, Kang (05-04). "United States Patent 4210764". Retrieved 2007-02-20.  CS1 maint: Date and year (link)
5. ^ S.C. Middleburgh, K.P.D. Lagerlof, R.W. Grimes - Accommodation of Excess Oxygen in Group II Oxides http://onlinelibrary.wiley.com/doi/10.1111/j.1551-2916.2012.05452.x/pdf
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. 

External links

• International Chemical Safety Card 0778