Calcium peroxide
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| Identifiers | |
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3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.013.764 |
| E number | E930 (glazing agents, ...) |
PubChem CID
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| CaO2 | |
| Molar mass | 72.0768 g/mol |
| Appearance | white to yellow powder |
| Odor | odorless |
| Density | 2.91 g/cm3 |
| Melting point | ~200 °C (decomp.) |
| decomposes | |
| Acidity (pKa) | 12.5 |
Refractive index (nD)
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1.895 |
| Structure | |
| Orthorhombic[1] | |
| Pna21 | |
| 8[1] | |
| Hazards | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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>5000 mg/kg (oral, rat) >10000 mg/kg (dermal, rat) |
| Related compounds | |
Other anions
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Calcium oxide |
Other cations
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Strontium peroxide Barium peroxide Sodium peroxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Calcium peroxide or Calcium dioxide (CaO2) is a solid peroxide with a white or yellowish color. For all practical purposes calcium peroxide is insoluble in water but will dissolve in acid to form hydrogen peroxide. When in contact with water it will immediately begin to decompose releasing oxygen.
Structure and stability
A theoretical study shows that the crystal structure of calcium peroxide is orthorhombic with space group Pna21, which explains the XRD spectrum excellently. First-principles calculations indicate that it is a stable compound against decomposition reaction: CaO2 → CaO + ½O2.[1]
Preparation
Calcium peroxide is created by the interactions of solutions of calcium salt and sodium peroxide, with subsequent crystallization.
The octahydrate is synthesized by the reaction of calcium hydroxide with dilute hydrogen peroxide.
Applications
Calcium peroxide is manufactured to varying specifications and purity and can be used in different areas of industry and agriculture. In agriculture it is used as an oxygen fertilizer, and is also used in the presowing treatments of rice seed. Also, calcium peroxide has found use in the aquaculture industry as it is used to oxygenate and disinfect water, and in the ecological restoration industry as it is used in the treatment of soils. Calcium Peroxide is used in a similar manner to magnesium peroxide for environmental restoration programs. It is used to restore soil and groundwater contaminated with petroleum hydrocarbons by stimulating aerobic microbial degradation of the contaminants in a process known as Enhanced In-Situ Bioremediation.
As a food additive it has the E number E930 and is used as flour bleaching agent and improving agent.
References
- ^ a b c Zhao, X.; Nguyen, M.C.; Wang, K.M.; Ho (2013). "Structures and stabilities of alkaline earth metal peroxides XO2 (X = Ca, Be, Mg) studied by a genetic algorithm". RSC Advances. doi:10.1039/C3RA43617A.
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