Barium oxide
| Barium oxide | |
|---|---|
 | |
| Other names Barium monoxide | |
| Identifiers | |
| CAS number | 1304-28-5  |
| PubChem | 62392 |
| ChemSpider | 56180 |
| RTECS number | CQ9800000 |
| Jmol-3D images | {{#if:[Ba]=O|Image 1 |
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| Properties | |
| Molecular formula | BaO |
| Molar mass | 153.326 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, cF8 |
| Space group | Fm3m, No. 225 |
| Coordination geometry |
Octahedral |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−582 kJ·mol−1[1] |
| Standard molar entropy S |
70 J·mol−1·K−1[2] |
| 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 |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 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.[3]
- 2Ba + O2 → 2BaO
- BaCO3 → BaO + CO2
It reacts with water to form barium hydroxide.
- BaO + H2O → Ba(OH)2
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.[4]
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.[5] 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.[6]
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.[7]
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]
References
- ↑ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X.
- ↑ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X.
- ↑ "Compounds of barium: barium (II) oxide". Web Elements. The University of Sheffield. 2007-01-26. Retrieved 2007-02-22.
- ↑ 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
- ↑ "Barium Oxide (chemical compound)". Encyclopædia Britanica. Encyclopædia Britanica. 2007. Retrieved 2007-02-19.
- ↑ Nield, Gerald; Washecheck, Paul; Yang, Kang (05-04). "United States Patent 4210764". Retrieved 2007-02-20.
- ↑ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- ↑ "Barium Oxide (ICSC)". IPCS. October 1999. Archived from the original on 26 February 2007. Retrieved 2007-02-19.
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