Calcium peroxide

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Calcium peroxide
Calcium peroxide
Identifiers
CAS number 1305-79-9 YesY
PubChem 14779
ChemSpider 14096 YesY
UNII 7FRO2ENO91 YesY
ChEBI CHEBI:48233 YesY
RTECS number EW3865000
Jmol-3D images Image 1
Properties
Molecular formula CaO2
Molar mass 72.0768 g/mol
Appearance white to yellow powder
Odor odorless
Density 2.91 g/cm3
Melting point ~200 °C (decomp.)
Solubility in water decomposes
Acidity (pKa) 12.5
Refractive index (nD) 1.895
Structure
Crystal structure Orthorhombic[1]
Space group Pna21
Coordination
geometry
8[1]
Hazards
EU Index Not listed
LD50
>5000 mg/kg (oral, rat)
>10000 mg/kg (dermal, rat)
Related compounds
Other anions Calcium oxide
Other cations Strontium peroxide
Barium peroxide
Sodium peroxide
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

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[edit]

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[edit]

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[edit]

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[edit]

  1. ^ 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.