Rubidium fluoride

Crystal structure
__ Rb +      __ F -
Crystal system	cubic
Space group	Fm 3 m (No. 225)
Lattice parameters	a = 565 pm
Coordination numbers	Rb [6], F [6]
General
Surname	Rubidium fluoride
other names	Rubidium (I) fluoride
Ratio formula	RbF
Brief description	white odorless solid
External identifiers / databases
CAS number 13446-74-7 EC number 236-603-2 ECHA InfoCard 100.033.262 PubChem 83473 ChemSpider 75311 Wikidata Q420338
properties
Molar mass	104.46 g mol −1
Physical state	firmly
density	3.58 g cm −3
Melting point	795 ° C
boiling point	1410 ° C
solubility	1306 g l −1 in water at 18 ° C
Refractive index	1.397
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 302-312-332-351 P: 280
MAK	2.5 mg m −3 (as fluoride)
Thermodynamic properties
ΔH f 0	−552.2 kJ mol −1
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Rubidium fluoride is a chemical compound between rubidium and fluorine . It does not occur in nature and easily dissolves in water. It's a to fluorides scoring salt , which in the sodium chloride structure crystallized.

Extraction and presentation

Rubidium can by reaction of hydrogen fluoride with rubidium or rubidium hydroxide , and subsequent drying receive:

${\displaystyle {\ce {Rb2CO3 + 2HF -> 2RbF + H2O + CO2 ^}}}$

${\displaystyle {\ce {RbOH + HF -> RbF + H2O}}}$

properties

It is a white crystalline substance with a cubic crystal structure , which looks very similar to table salt (NaCl). The crystals belong to the space group Fm 3 m (space group no. 225) with the lattice parameter a = 565 pm and four formula units per unit cell . The refractive index of the crystals is n _D  = 1.398. Rubidium fluoride colors a flame ( Bunsen burner flame ) purple or magenta (spectral analysis).

Rubidium fluoride forms two different hydrates, a sesquihydrate with the stoichiometric composition 2RbF · 3H ₂ O and a third hydrate with the composition 3RbF · H ₂ O.

In addition to the simple rubidium fluoride, an acidic rubidium fluoride with the empirical formula HRbF _{2 is} known, which can be produced by the reaction of rubidium fluoride and hydrogen fluoride. The compounds H ₂ RbF ₃ and H ₃ RbF ₄ were also synthesized.

The solubility in acetone is 0.0036 g / kg at 18 ° C and 0.0039 g / kg at 37 ° C.

The standard enthalpy of formation of rubidium  fluoride is Δ _f H ⁰ ₂₉₈ = −552.2 kJ mol ⁻¹ , the standard free enthalpy of formation ΔG ⁰ ₂₉₈  = −520.4 kJ mol ⁻¹ , and the standard molar entropy S ⁰ ₂₉₈  = 113.9 J. K ⁻¹ mol ⁻¹ . The enthalpy of solution of rubidium fluoride was determined to be −24.28 kJ / mol.

safety instructions

Due to the fluoride it contains, contact with the skin and swallowing should be avoided when handling rubidium fluoride .

Individual evidence

1. ↑ ^{a b c d e f} data sheet rubidium fluoride at AlfaAesar, accessed on January 29, 2010 ( PDF )(JavaScript required) . .
2. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Index of Refraction of Inorganic Crystals, pp. 10-247.
3. ↑ ^{a b} Data sheet Rubidium fluoride from Sigma-Aldrich , accessed on April 22, 2011 ( PDF ).
4. ↑ ^{a b c d} R. E. Dickerson, HB Gray, H.-W. Sighting, MY Darensbourg: Principles of Chemistry . Walter de Gruyter, 1988, ISBN 978-3-11-009969-0 , p. 976 ( limited preview in Google Book Search [accessed December 1, 2018]).
5. ↑ ^{a b c} H. Eggeling, J. Meyer: About the fluorides of rubidium . In: Journal of Inorganic Chemistry . tape 46 , 1905, pp. 174 ff . ( Full text ).
6. ^ ^{A b} Jean D'Ans, Ellen Lax: Paperback for chemists and physicists . 3. Elements, inorganic compounds and materials, minerals. 4th edition. tape 3 . Springer, 1997, ISBN 978-3-540-60035-0 , pp. 686 ( limited preview in Google Book Search [accessed December 1, 2018]).
7. ↑ M. de Forcrand: Sur les hydrates des fluorures de rubidium et de cesium . In: Compt. Rend. Hebd. tape 152 , 1911, pp. 1208 ( full text ).
8. ↑ Han Eggerling, Julius Meyer: About the fluorides of rubidium . In: Journal of Inorganic Chemistry . tape 46 , no. 1 , 1905, pp. 174-176 , doi : 10.1002 / zaac.19050460111 .
9. ^ A Text-Book of Inorganic Chemistry . Forgotten Books, ISBN 978-1-4510-0469-4 , pp. 209 ( limited preview in Google Book search).
10. ↑ Aterton Seidell: Solubilities Of Organic Compounds . tape 1 , p. 1437 ( full text ).
11. ↑ M. de Forcrand: Étude thermochimique de quelques composés binaires des métaux alcalins et alcalino-terreux . In: Compt. Rend. Hebd. tape 152 , 1911, pp. 27 f . ( Full text ).

Web links

• Webelements.com: Rubidium fluoride (engl.)