Barium peroxide

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Barium peroxide
Peroxid barnatý.JPG
BaO2structure.jpg
Identifiers
CAS number 1304-29-6 YesY
PubChem 14773
ChemSpider 14090 YesY
EC number 215-128-4
RTECS number CR0175000
Jmol-3D images Image 1
Properties
Molecular formula BaO2
Molar mass 169.33 g/mol (anhydrous)
313.45 (octahydrate)
Appearance Grey-white crystalline (anhydrous)
colorless solid (octahydrate)
Odor odorless
Density 5.68 g/cm3 (anhydrous) 2.292 g/cm3 (octahydrate)
Melting point 450 °C (842 °F; 723 K)
Boiling point 800 °C (1,470 °F; 1,070 K) (decomposes to BaO & O2.[1])
Solubility in water anhydrous
0.091 g/100 mL (20 °C)
octahydrate
0.168 g/cm3
Solubility dissolves with decomposition in acid
Structure
Crystal structure Tetragonal [2]
Space group D174h, I4/mmm, tI6
Coordination
geometry
6
Hazards
EU Index 056-001-00-1
EU classification Oxidant (O)
Harmful (Xn)
R-phrases R8, R20/22
S-phrases (S2), S13, S27
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Barium peroxide is the inorganic compound with the formula BaO2. This white solid (gray when impure) is one of the most common inorganic peroxides, and it was the first peroxide compound discovered. Being an oxidizer and giving a vivid green colour upon ignition (as do all barium compounds), it finds some use in fireworks; historically, it was also used as a precursor for hydrogen peroxide.[3]

Structure[edit]

Barium peroxide is a peroxide, containing O2−
2
subunits. The solid adopts the same structure as, i.e. is isomorphous to, calcium carbide, CaC2.

Preparation and use[edit]

Barium peroxide arises by the reversible reaction of O2 with barium oxide. The peroxide forms around 500 °C and oxygen is released above 820 °C.[1]

2 BaO + O2 2 BaO2

This reaction is the basis for the now-obsolete Brin process for separating oxygen from the atmosphere. Other oxides, e.g. Na2O and SrO, behave similarly.[4]

In another obsolete application, barium peroxide was once used to produce hydrogen peroxide via its reaction with sulfuric acid:[3]

BaO2 + H2SO4 → H2O2 + BaSO4

The insoluble barium sulfate is filtered from the mixture.

Footnotes[edit]

  1. ^ a b Accommodation of Excess Oxygen in Group II Monoxides - S.C. Middleburgh, R.W. Grimes and K.P.D. Lagerlof Journal of the American Ceramic Society 2013, Volume 96, pages 308–311. doi:10.1111/j.1551-2916.2012.05452.x
  2. ^ Massalimov, I. A.; Kireeva, M. S.; Sangalov, Yu. A. (2002). Inorganic Materials 38 (4): 363. doi:10.1023/A:1015105922260. 
  3. ^ a b Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort (2005), "Peroxo Compounds, Inorganic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a19_177.pub2 
  4. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.

See also[edit]

External links[edit]