Rubidium iodide
Chemical compound
From Wikipedia, the free encyclopedia
Rubidium iodide, more specifically rubidium monoiodide, is a salt of rubidium and iodine, with the chemical formula RbI. It is a white solid with a melting point of 646.85 °C.
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| Names | |
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| IUPAC name
Rubidium iodide | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.029.271 |
PubChem CID |
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| RbI | |
| Molar mass | 212.3723 g/mol |
| Appearance | white solid |
| Density | 3.110 g/cm 3 |
| Melting point | 646.85 °C (1,196.33 °F; 920.00 K) |
| Boiling point | 1,304 °C (2,379 °F; 1,577 K) |
| 152 g/100 mL | |
| −72.2·10−6 cm3/mol | |
Refractive index (nD) |
1.6474[1] |
| Hazards | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
4708 mg/kg (oral, rat) |
| Safety data sheet (SDS) | External MSDS |
| Thermochemistry[2] | |
Std molar entropy (S⦵298) |
118.11 J·K−1·mol−1 |
Std enthalpy of formation (ΔfH⦵298) |
−328.7 kJ·mol−1 |
Gibbs free energy (ΔfG⦵) |
−325.7 kJ·mol−1 |
| Related compounds | |
Other anions |
Rubidium fluoride Rubidium chloride Rubidium bromide Rubidium astatide |
Other cations |
Lithium iodide Sodium iodide Potassium iodide Caesium iodide Francium iodide |
Related compounds |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Properties
Rubidium iodide forms colorless crystals, and has a red-violet flame color.
It is easily soluble in water, liquid ammonia, sulfuric acid, RbI·6NH3 and RbI·3SO2. Rubidium iodide is soluble only in the following solvents:
| Solvent | 0 °C | 25 °C |
|---|---|---|
| Acetonitrile | 1.478 | 1.350 |
| Propionitrile | 0.274 | 0.305 |
| Nitromethane | 0.567 | 0.518 |
| Acetone | 0.960 | 0.674 |
| Furfural | 4,930 |
Structure
Rubidium iodide has a sodium chloride structure; its lattice constant is a = 7.326 Å, and the Rb–I bond length is 3.66 Å.[4]
Preparation
Rubidium iodide can be synthesized in several ways. One is to use a mixed reaction of rubidium hydroxide and hydriodic acid/hydrogen iodide:[5]
- RbOH + HI → RbI + H2O
Another method is to neutralize rubidium carbonate with hydriodic acid:[5]
- Rb2CO3 + 2HI → 2RbI + H2O + CO2
Another method is to use rubidium metal to react directly with iodine, but because rubidium metal is very expensive, it is the least commonly used method. In addition, rubidium reacts violently with halogens and burns:[5]
- 2Rb + I2 → 2RbI
Applications
Rubidium iodide is used as a component of eye drops, in which it is sold in Romania under the name Rubjovit (containing 8 mg/ml RbI).[6] Another product is Polijodurato. However, there are studies that show that rubidium iodide has allergy-triggering[7] and inflammation-causing[8] side effects. Homeopathic products containing rubidium iodide are available under the name Rubidium iodatum. In the past, towards the end of the 19th century, it was used to treat syphilis.[9]
Rubidium iodide has isolated uses in organic synthesis, for example for the targeted saponification of a polymethylated phosphate.[10]
Reactions
Rubidium iodide reacts with halogens to form polyhalides: RbI3, RbICl2, RbICl4.[4]