Names | |
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Other names
Rubidium(I) Fluoride
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Identifiers | |
3D model (
JSmol)
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ChemSpider | |
ECHA InfoCard | 100.033.262 |
PubChem
CID
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RTECS number |
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UNII | |
CompTox Dashboard (
EPA)
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Properties | |
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) |
130.6 g/100 mL (18 °C) | |
−31.9·10−6 cm3/mol | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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Toxic |
NFPA 704 (fire diamond) | |
Flash point | Non-flammable |
Related compounds | |
Other
anions
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Rubidium chloride Rubidium bromide Rubidium iodide Rubidium astatide |
Other
cations
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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).
|
Rubidium fluoride (RbF) is the fluoride salt of rubidium. It is a cubic crystal with rock-salt structure.
There are several methods for synthesising rubidium fluoride. One involves reacting rubidium hydroxide with hydrofluoric acid: [1]
Another method is to neutralize rubidium carbonate with hydrofluoric acid: [1]
Another possible method is to react rubidium hydroxide with ammonium fluoride:
The least used method due to expense of rubidium metal is to react it directly with fluorine gas, as rubidium reacts violently with halogens: [1]
Rubidium fluoride is a white crystalline substance with a cubic crystal structure that looks very similar to common salt (NaCl). The crystals belong to the space group Fm3m (space group no. 225) with the lattice parameter a = 565 pm and four formula units per unit cell. [2] The refractive index of the crystals is nD = 1.398. [2] Rubidium fluoride colors a flame (Bunsen burner flame) purple or magenta red (spectral analysis).
Rubidium fluoride forms two different hydrates, a sesquihydrate with the stoichiometric composition 2RbF·3H2O and a third hydrate with the composition 3RbF·H2O. [3]
In addition to simple rubidium fluoride, an acidic rubidium fluoride with the molecular formula HRbF2 is also known, [4] which can be produced by reacting rubidium fluoride and hydrogen fluoride. [4] The compounds H2RbF3 and H3RbF4 were also synthesized. [5] [4]
The solubility in acetone is 0.0036 g/kg at 18 °C and 0.0039 g/kg at 37 °C. [6]
The standard enthalpy of formation of rubidium fluoride is ΔfH0298 = −552.2 kJ mol−1, [7] the standard free enthalpy of formation ΔG0298 = −520.4 kJ mol−1, [7] and the standard molar entropy S0298 = 113.9 J K −1 ·mol−1. [7] The enthalpy of solution of rubidium fluoride was determined to be −24.28 kJ/mol. [8]