Calcium peroxide

Crystal structure
General
Surname	Calcium peroxide
other names	Calcium superoxide Calcium dioxide E 930 CALCIUM PEROXIDE ( INCI )
Ratio formula	CaO 2
Brief description	white solid or as octahydrate pearlescent scales
External identifiers / databases
CAS number 1305-79-9 78403-22-2 EC number 215-139-4 ECHA InfoCard 100,013,764 PubChem 14779 ChemSpider 14096 Wikidata Q94770
properties
Molar mass	72.08 g mol −1
Physical state	firmly
density	2.92 g cm −3
Melting point	275 ° C (decomposition)
solubility	practically insoluble in water (<0.01% at 20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 272-314 P: 210-221-280-301 + 330 + 331-303 + 361 + 353-305 + 351 + 338-310-371 + 380 + 375
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Calcium peroxide is an inorganic chemical compound from the group of peroxides .

Extraction and presentation

Calcium peroxide can be obtained by reacting a soluble calcium salt (e.g. calcium chloride or calcium nitrate ) with hydrogen peroxide in an alkaline solution (e.g. sodium hydroxide or ammonia ). Technical calcium peroxide also contains calcium carbonate and calcium hydroxide to a large extent and is obtained by reacting calcium oxide or calcium hydroxide and hydrogen peroxide.

${\displaystyle \mathrm {Ca(OH)_{2}+H_{2}O_{2}\longrightarrow CaO_{2}+2\ H_{2}O} }$

properties

Crystal structure of calcium peroxide
           __ Ca ²⁺     __ O ^-

Calcium peroxide is a strong oxidizing agent and has a medium oxidizing effect, as it releases oxygen when heated. It is often present as octahydrate, which loses the water of crystallization at around 130 ° C. The octahydrate has a tetragonal crystal structure with a = 619.7 pm, c = 1096.7 pm and the space group P 4 / mcc (space group no. 124) . The solubility in water at 20 ° C and neutral pH is less than 0.01%. The reaction with water is a hydrolysis that lasts between 6 and 8 weeks and releases molecular oxygen:

${\displaystyle \mathrm {2\ CaO_{2}+2\ H_{2}O\longrightarrow 2\ Ca(OH)_{2}+O_{2}} }$

Calcium peroxide dissolves in acid, releasing hydrogen peroxide. Calcium peroxide forms insoluble apatite with orthophosphate and can therefore lower the phosphate content in water.

use

Calcium peroxide is used as a drying accelerator for polysulfide elastomers , an antiseptic in toothpastes and chewing gum, as a stabilizer in the rubber industry, in dentistry (to disinfect the root canal and heal periapical inflammation), as a dough improver in the baking industry and as a seed disinfectant. Due to its phosphorus-binding properties, calcium peroxide is used as a phosphate binding agent in water. Because of the slow release of oxygen, organic components of sediments in water can be broken down in situ (lake restoration).

Web links

• E. Vernon Ballou, Peter C. Wood, LeRoy A. Spitze, Theodore Wydeven: The Preparation of Calcium Superoxide from Calcium Peroxide Diperoxyhydrate . In: Ind. Eng. Chem. Prod. Res. Dev. , 1977 , 16  (2), pp. 180-186 ( doi : 10.1021 / i360062a015 ).

Individual evidence

1. ↑ Entry on CALCIUM PEROXIDE in the CosIng database of the EU Commission, accessed on February 16, 2020.
2. ↑ ^{a b c d e} Entry on calcium peroxide in the GESTIS substance database of the IFA , accessed on January 28, 2020(JavaScript required) .
3. ↑ ^{a b} Yong Ma, Bo-Tao Zhang and a .: Study on the generation mechanism of reactive oxygen species on calcium peroxide by chemiluminescence and UV-visible spectra. In: Luminescence. 22, 2007, p. 575, doi : 10.1002 / bio.1003 .
4. ↑ Entry on calcium peroxide. In: Römpp Online . Georg Thieme Verlag, accessed on January 2, 2015.
5. ↑ Calcium peroxide data sheet (PDF; 159 kB) from Solvay, accessed on February 1, 2018.
6. ↑ GV Shilov, AI Karelin, DG Lemesheva, LS Leonova, LO Atovmyan: Crystal Structure and Properties of CaO ₂ · 8H ₂ O , Russian Journal of Inorganic Chemistry , Vol. 50, No. 6, June 2005, pp. 842-847.
7. ↑ Patent: EP 1080042
8. ↑ Malyk Yuriy: In-Vitro Investigations on the Use of Sealer Materials Containing Calcium Peroxide in Endodontic Therapy. urn : nbn: de: bvb: 19-43959