Barium oxide

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Barium oxide
NaCl polyhedra.png
200px
Names
Other names
Barium monoxide
Barium protoxide
Calcined baryta
Baria
Identifiers
1304-28-5 YesY
ChemSpider 56180 YesY
Jmol 3D model Interactive image
PubChem 62392
RTECS number CQ9800000
  • InChI=1S/Ba.O YesY
    Key: QVQLCTNNEUAWMS-UHFFFAOYSA-N YesY
  • InChI=1/Ba.O/rBaO/c1-2
    Key: QVQLCTNNEUAWMS-FXUTYLCTAB
  • [Ba]=O
Properties
BaO
Molar mass 153.326 g/mol
Appearance white 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
Structure
cubic, cF8
Fm3m, No. 225
Octahedral
Thermochemistry
70 J·mol−1·K−1[1]
−582 kJ·mol−1[2]
Vapor pressure {{{value}}}
Related compounds
Other anions
Barium hydroxide
Barium peroxide
Other cations
Calcium oxide
Strontium oxide
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
N verify (what is YesYN ?)
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.

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


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.[3] 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.[4]

It is also a source of pure oxygen through heat fluctuation. It readily oxidises to BaO1+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.[5]

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.[6] Likewise, it is often formed through the decomposition of other barium salts.[7]

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

References

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  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
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External links