Lithium peroxide

Crystal structure
__ Li +      __ O -
General
Surname	Lithium peroxide
other names	Dilithium peroxide
Ratio formula	Li 2 O 2
Brief description	white solid
External identifiers / databases
CAS number 12031-80-0 EC number 234-758-0 ECHA InfoCard 100,031,585 PubChem 25489 Wikidata Q411763
properties
Molar mass	45.88 g mol −1
Physical state	firmly
density	2.36 g cm −3
Melting point	Decomposition from 340 ° C
solubility	exothermic reaction with water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 272-314 P: 220-280-305 + 351 + 338-310
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Lithium peroxide , Li ₂ O _2, is an oxygen compound of the alkali metal lithium .

Manufacturing

It is represented by reacting lithium hydroxide with hydrogen peroxide and then heating with elimination of hydrogen peroxide

${\displaystyle \mathrm {LiOH\ +\ H_{2}O_{2}\longrightarrow \ LiOOH\ +\ H_{2}O} }$

${\displaystyle \mathrm {2\ LiOOH\ {\xrightarrow {\Delta T}}\ Li_{2}O_{2}\ +\ H_{2}O_{2}} }$

properties

Lithium peroxide is a colorless, usually yellowish solid in its purest form. Hydrogen peroxide is formed with water. The compound has a hexagonal crystal structure with the space group P 6 ₃ / mmc (space group no. 194) and the lattice parameters a = 3.183 Å and c = 7.726 Å. The crystal structure contains two crystallographically different Li atoms. One is coordinated by the six oxygen atoms of three peroxide ions, the second in a distorted octahedron by the oxygen atoms of six neighboring peroxide ions. The standard enthalpy of formation of lithium peroxide is ΔH _f ⁰  = −633 kJ / mol.

use

Lithium peroxide can be used to produce high-purity lithium oxide . Here, lithium peroxide is decomposed at 195 ° C, with lithium oxide and oxygen being formed:

${\displaystyle \mathrm {2\ Li_{2}O_{2}\longrightarrow 2\ Li_{2}O+O_{2}} }$

It is also used in space travel to regenerate life-sustaining gas supply systems. It reacts with carbon dioxide to form lithium carbonate and oxygen. This removes carbon dioxide from the air we breathe and releases oxygen.

${\displaystyle \mathrm {2\ Li_{2}O_{2}+2\ CO_{2}\longrightarrow 2\ Li_{2}CO_{3}+O_{2}} }$

Lithium peroxide is used as a hardener for special polymers. It is still used for the lithium peroxide accumulators that are currently being developed or formed in the battery during discharge operation.

Individual evidence

1. ↑ Entry on lithium oxide. In: Römpp Online . Georg Thieme Verlag, accessed on July 14, 2014.
2. ↑ ^{a b c} data sheet lithium peroxide from AlfaAesar, accessed on December 15, 2010 ( PDF )(JavaScript required) .
3. ↑ ^{a b} data sheet lithium peroxide from Sigma-Aldrich , accessed on April 8, 2011 ( PDF ).
4. ^ ^{A b} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1263.
5. ↑ Luis Guillermo Cota, Pablo de la Mora: On the structure of lithium peroxide, Li ₂ O ₂ . In: Acta Crystallographica Section B Structural Science. 61, 2005, pp. 133-136, doi : 10.1107 / S0108768105003629 .
6. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1176.
7. ^ NN Greenwood, A. Earnshaw: Chemistry of the Elements . 1997, 2nd edition, Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4 .
8. ↑ patent DE2365449 1975 Thiokol Chemical Corp.