Chemistry:Rubidium fluoride

Rubidium fluoride

Names
Other names Rubidium(I) Fluoride
Identifiers
CAS Number	13446-74-7 Y
3D model (JSmol)	Interactive image
ChemSpider	75311 Y
PubChem CID	83473
RTECS number	VL8740000
UNII	63564TNJ4R Y
InChI InChI=1S/FH.Rb/h1H;/q;+1/p-1 Y Key: AHLATJUETSFVIM-UHFFFAOYSA-M Y InChI=1/FH.Rb/h1H;/q;+1/p-1 Key: AHLATJUETSFVIM-REWHXWOFAO
SMILES [Rb+].[F-]
Properties
Chemical formula	RbF
Molar mass	104.4662 g/mol
Appearance	white crystalline solid
Density	3.557 g/cm3
Melting point	795 °C (1,463 °F; 1,068 K)
Boiling point	1,408 °C (2,566 °F; 1,681 K)
Solubility in water	130.6 g/100 mL (18 °C)
Solubility in acetone	0.0036 g/kg (18 °C) 0.0039 g/kg (37 °C)
Magnetic susceptibility (χ)	−31.9·10−6 cm3/mol
Refractive index (nD)	1.398
Structure
Space group	Fm3m (No. 225)
Lattice constant	a = 565 pm
Formula units (Z)	4
Thermochemistry
Std molar entropy (So298)	113.9 J·mol-1·K-1
Std enthalpy of formation (ΔfH⦵298)	−552.2 kJ/mol
Gibbs free energy (ΔfG˚)	−520.4 kJ/mol
Hazards
Main hazards	Toxic
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	HH301Category:GHS errors, HH302Category:GHS errors, HH311Category:GHS errors, HH312Category:GHS errors, HH315Category:GHS errors, HH319Category:GHS errors, HH331Category:GHS errors, HH332Category:GHS errors, HH335Category:GHS errors, HH351Category:GHS errors
GHS precautionary statements	PP203Category:GHS errors, PP261Category:GHS errors, PP262Category:GHS errors, PP264Category:GHS errors, PP264+P265Category:GHS errors, PP270Category:GHS errors, PP271Category:GHS errors, PP280Category:GHS errors, PP301+P316Category:GHS errors, PP301+P317Category:GHS errors, PP302+P352Category:GHS errors, PP304+P340Category:GHS errors, PP305+P351+P338Category:GHS errors, PP316Category:GHS errors, PP317Category:GHS errors, PP318Category:GHS errors, PP319Category:GHS errors, PP321Category:GHS errors, PP330Category:GHS errors, PP332+P317Category:GHS errors, PP337+P317Category:GHS errors, PP361+P364Category:GHS errors, PP362+P364Category:GHS errors, PP403+P233Category:GHS errors, PP405Category:GHS errors
NFPA 704 (fire diamond)	0 3 0
Flash point	Non-flammable
Threshold limit value (TLV)	2.5 mg/m3, as F
NIOSH (US health exposure limits):
PEL (Permissible)	2.5 mg/m3, as F
Related compounds
Other anions	Rubidium chloride Rubidium bromide Rubidium iodide Rubidium astatide
Other cations	Lithium fluoride Sodium fluoride Potassium fluoride Caesium fluoride Francium fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Rubidium fluoride (RbF) is the fluoride salt of rubidium. It is a white crystalline solid with a cubic crystal structure, similar to common salt. It forms two different hydrates, a sesquihydrate with the stoichiometric composition 2RbF·3H₂O and a third hydrate with the composition 3RbF·H₂O.

Synthesis

There are several methods for synthesising rubidium fluoride. One involves reacting rubidium hydroxide with hydrofluoric acid:

RbOH + HF → RbF + H₂O

Another method is to neutralize rubidium carbonate with hydrofluoric acid:

Rb₂CO₃ + 2HF → 2RbF + H₂O + CO₂

Another possible method is to react rubidium hydroxide with ammonium fluoride:

RbOH + NH₄F → RbF + H₂O + NH₃

The least used method due to expense of rubidium metal is to react it directly with fluorine gas, as rubidium reacts violently with halogens:

2Rb + F₂ → 2RbF

Properties

The enthalpy of solution of rubidium fluoride was determined to be −24.28 kJ/mol.

Rubidium fluoride has a purple or magenta red flame test.

Related compounds

In addition to simple rubidium fluoride, an acidic rubidium fluoride with the molecular formula HRbF₂ is also known, which can be produced by reacting rubidium fluoride and hydrogen fluoride. The compounds H₂RbF₃ and H₃RbF₄ were also synthesized.