Rubidium oxide

Crystal structure
Rb + : __ O 2− : __
General
Surname	Rubidium oxide
Ratio formula	Rb 2 O
Brief description	colorless crystals
External identifiers / databases
CAS number 18088-11-4 EC number 241-993-2 ECHA InfoCard 100.038.161 PubChem 10154361 ChemSpider 8329869 Wikidata Q425243
properties
Molar mass	186.93 g mol −1
Physical state	firmly
density	3.72 g · cm -3
Melting point	400 ° C (decomposition)
solubility	violent reaction with water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 260-314-318 P: ?
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Rubidium oxide is an oxide of rubidium that reacts violently with water . It does not occur in nature.

properties

Rubidium oxide is a colorless, crystalline solid that turns yellow when heated. The salt crystallizes in an anti- calcium fluoride structure. The crystals are cubic with the space group Fm 3 m (space group no. 225) , the lattice parameter a = 674 pm and four formula units per unit cell . Rubidium oxide reacts violently with water:

${\displaystyle \mathrm {Rb_{2}O+H_{2}O\longrightarrow 2\ RbOH} }$

The standard enthalpy of formation of rubidium oxide is ΔH _f ⁰  = −331 kJ / mol.

When exposed to light, it slowly decomposes with a dark color.

Extraction and presentation

Rubidium oxide can be made by reacting rubidium and rubidium hydroxide :

${\displaystyle \mathrm {2\ Rb+2\ RbOH\longrightarrow 2\ Rb_{2}O+H_{2}} }$

further synthesis possibilities are:

${\displaystyle \mathrm {3\ Rb+RbO_{2}\longrightarrow 2\ Rb_{2}O} }$

and

${\displaystyle \mathrm {10\ Rb+2\ RbNO_{3}\longrightarrow 6\ Rb_{2}O+N_{2}} }$

such as

${\displaystyle {\ce {2 Rb + HgO -> Rb2O + Hg}}}$.

In contrast, the direct reaction of rubidium and oxygen produces rubidium hyperoxide RbO ₂ (mainly) or rubidium peroxide Rb ₂ O ₂ .

safety instructions

Since rubidium oxide reacts strongly with water, it acts as a base on the skin . When handling rubidium oxide, contact with the skin should therefore be avoided.

Individual evidence

1. ↑ ^{a b c d e f g} Georg Brauer: Dialkalimonoxyde - Rubidiumoxyd . In: Handbook of Preparative Inorganic Chemistry . Ferdinand Enke Verlag, Stuttgart 1954, p. 738 .
2. ↑ Registration dossier on Dirubidium oxide ( GHS section ) at the European Chemicals Agency (ECHA), accessed on July 12, 2020.
3. ^ ^{A b} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1176.
4. ^ Jean D'Ans, Ellen Lax: Pocket book for chemists and physicists. Volume 3: R. Blachnik (Ed.): Elements, inorganic compounds and materials, minerals. 4th revised and revised edition. Springer, Berlin et al. 1997, ISBN 3-540-60035-3 , p. 690 ( limited preview in the Google book search).

Web links

• Entry to rubidium oxide . In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD