Hubbry Logo
Rubidium hydroxideRubidium hydroxideMain
Open search
Rubidium hydroxide
Community hub
Rubidium hydroxide
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Rubidium hydroxide
Rubidium hydroxide
Rubidium hydroxide
View on Wikipedia
from Wikipedia
Rubidium hydroxide
Names
IUPAC name
Rubidium hydroxide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.013.806 Edit this at Wikidata
RTECS number
  • VL8750000
UNII
  • InChI=1S/H2O.Rb/h1H2;/q;+1/p-1 checkY
    Key: CPRMKOQKXYSDML-UHFFFAOYSA-M checkY
  • InChI=1/H2O.Rb/h1H2;/q;+1/p-1
    Key: CPRMKOQKXYSDML-REWHXWOFAO
  • [Rb+].[OH-]
Properties
RbOH
Molar mass 102.475 g·mol−1
Appearance white solid,
hygroscopic
Density 3.1 g/mL at 25 °C
Melting point 382 °C (720 °F; 655 K) dec
Boiling point 1,390 °C (2,530 °F; 1,660 K)
173 g/100 mL (30 °C)
Solubility soluble in ethanol
Acidity (pKa) 15.4[1]
Thermochemistry
−413.8 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Corrosive
GHS labelling:
GHS05: Corrosive
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard ALK: Alkaline
3
0
1
ALK
Flash point Non-flammable
Related compounds
Other cations
 Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Cesium hydroxide
Related compounds
 Rubidium oxide (+1)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Rubidium hydroxide is the inorganic compound with the formula RbOH. It consists of rubidium cations and an equal number of hydroxide anions. It is a colorless solid that is commercially available as aqueous solutions from a few suppliers. Like other strong bases, rubidium hydroxide is highly caustic. Rubidium hydroxide is formed when rubidium metal reacts with water.[2]

Uses

[edit]

Rubidium hydroxide is rarely used in industrial processes because potassium hydroxide and sodium hydroxide can perform nearly all the same functions of rubidium hydroxide. Metal oxide catalysts are sometimes modified with rubidium hydroxide.[2]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Rubidium hydroxide

View on Grokipedia
from Grokipedia
Rubidium hydroxide is an with the RbOH, consisting of cations and hydroxide anions. This strong , analogous to other metal hydroxides, appears as a colorless to grayish-white hygroscopic crystalline solid that is highly soluble in , fully dissociating to produce a caustic solution with values exceeding 14. Key physical properties include a density of 3.2 g/cm³ for the solid, a of 301 °C (though it may decompose at high temperatures). It exhibits extreme hygroscopicity, rapidly absorbing moisture from air, and reacts with atmospheric to form rubidium and . Dissolution in is highly exothermic, often generating enough to boil the solution, and the resulting aqueous form has a of about 1.74 g/mL at 25 °C for concentrated solutions. Rubidium hydroxide finds limited industrial application due to the scarcity and expense of , but it is employed in electric storage batteries, , , and as a in specialized chemical syntheses, such as for oxidative reactions or in the preparation of other compounds. It is also used sparingly in scientific research for its strong basicity in organic and inorganic reactions. As a highly corrosive substance, rubidium hydroxide poses significant hazards, causing severe burns upon contact with or eyes and irritating the if inhaled; protective equipment is essential when handling it. It is classified as a dangerous good for transport under UN 2678 (Class 8, corrosive) for the solid form.

Properties

Physical properties

Rubidium hydroxide is a colorless to grayish-white, hygroscopic solid that readily absorbs moisture from the air, often forming hydrates such as the monohydrate RbOH·H₂O. Its is 102.475 g/mol. The compound has a density of 3.2 g/cm³. It melts at 301 °C (300–302 °C), and decomposes at approximately 1,390 °C. Rubidium hydroxide exhibits high in , dissolving at a rate of 173 g/100 mL at 30 °C, and is also soluble in .

Chemical properties

Rubidium hydroxide has the RbOH and consists of cations (Rb⁺) and anions (OH⁻) arranged in an ionic lattice. As a base, it fully dissociates in to yield Rb⁺ and OH⁻ ions, producing a highly alkaline solution. The pKa of its conjugate acid () is 15.7, underscoring its strong basicity comparable to other metal hydroxides. Its hygroscopic nature arises from the strong ionic attraction of Rb⁺ and OH⁻ to molecules, readily absorbing moisture from the air. In general reactivity, rubidium hydroxide acts as a base by neutralizing acids and, upon exposure to atmospheric CO₂, forms (Rb₂CO₃).

Preparation

Reaction with water

Rubidium hydroxide is synthesized on a laboratory scale through the direct reaction of metal with , serving as the primary method for small-scale preparation due to its straightforward nature. The balanced for the reaction is: 2Rb(s)+2H2O(l)→2RbOH(aq)+H2(g)2 \mathrm{Rb}(s) + 2 \mathrm{H_2O}(l) \rightarrow 2 \mathrm{RbOH}(aq) + \mathrm{H_2}(g) This process produces gas and a colorless of rubidium hydroxide. The reaction is highly exothermic, reflecting the standard enthalpy of formation of RbOH at −417.0 kJ/mol, which results in rapid heat release, vigorous bubbling, and potential ignition of the evolved . To manage these hazards, small pieces of freshly cut metal are added incrementally to in a well-ventilated or under an inert atmosphere, preventing excessive splashing or vessel rupture from the violent agitation. Following the reaction, the aqueous RbOH solution is evaporated under controlled conditions, often at reduced and low temperature, to yield the solid compound as a monohydrate or form depending on the parameters. Yields are typically near quantitative, limited primarily by mechanical losses during gas evolution rather than incomplete conversion.

From other rubidium compounds

Rubidium hydroxide can be prepared from other rubidium compounds through hydration or double displacement reactions, which are particularly useful in settings or when starting from more readily available rubidium salts. A straightforward method involves the hydration of . The reacts exothermically with according to the equation Rb2O+H2O→2RbOH\mathrm{Rb_2O + H_2O \rightarrow 2 RbOH} where the is slowly added to under controlled conditions to form the solution; the product can then be concentrated and recrystallized if needed. is also synthesized from carbonate via reaction with : Rb2CO3+Ca(OH)2→2RbOH+CaCO3\mathrm{Rb_2CO_3 + Ca(OH)_2 \rightarrow 2 RbOH + CaCO_3} The mixture is heated, and the insoluble precipitate is separated by , leaving a solution of that is subsequently evaporated to the desired concentration. Additional routes include electrolysis of aqueous rubidium chloride solutions, where hydroxide ions accumulate at the cathode to form RbOH, similar to industrial chlor-alkali processes, with chlorine gas evolving at the anode. Another approach uses rubidium sulfate treated with barium hydroxide: Rb2SO4+Ba(OH)2→2RbOH+BaSO4\mathrm{Rb_2SO_4 + Ba(OH)_2 \rightarrow 2 RbOH + BaSO_4} The insoluble barium sulfate is filtered off, and the filtrate is processed to isolate the hydroxide, often using corrosion-resistant containers like nickel due to the basic nature of the solution. Commercial production of hydroxide remains limited and uncommon, primarily because rubidium is a with low global demand; rubidium hydroxide is produced in limited quantities commercially, often by converting rubidium salts (such as carbonates) recovered as byproducts from the processing of lithium-bearing minerals like , which involves acid leaching or followed by separation and conversion steps. The commercial product is typically a 50% , obtained by concentrating the prepared solution via partial evaporation. These preparation methods are thermodynamically favored, as reflected by the of RbOH at −417.0 kJ/mol, indicating the strongly exothermic character of the hydration steps from and the stability of the resulting .

Uses

Catalyst modification

Rubidium hydroxide plays a key role in modifying metal catalysts for , particularly by enhancing selectivity in dehydrogenation reactions through promotion of basic sites. In processes like the side-chain of with , which involves dehydrogenation of to , RbOH modification improves catalyst efficiency by balancing acid-base properties. Specific examples include doping catalysts with RbOH to fine-tune acidity and basicity. For instance, of X molecular sieves with RbOH, often in combination with KOH and CsOH, creates multi-ion modified zeolites that achieve high utilization (up to 49.5%) and selectivity (95.8%) toward styrene and . Similarly, postsynthetic of Rb onto USY zeolites using RbOH in alcoholic media introduces isolated basic sites, enabling >90% selectivity in the self-condensation of propanal to its aldol product, a reaction relevant to bio-oil upgrading. RbOH is also used as a catalyst in oxidative chlorination reactions. Compared to sodium or hydroxides, RbOH offers advantages due to rubidium's larger (1.52 Å versus 1.02 Å for Na⁺ and 1.38 Å for K⁺), which influences catalyst pore structure, enhances cation incorporation efficiency, and provides stronger basicity promotion without excessive dealumination. This leads to better in bifunctional , though RbOH's higher cost limits its use to specialty chemical processes rather than large-scale applications. It serves as a reagent in the preparation of other rubidium compounds.

Battery applications

Rubidium hydroxide has been employed as an electrolyte component in alkaline storage batteries, particularly in nickel-cadmium and nickel-iron types, where it serves as a major alkali hydroxide in aqueous solutions at concentrations ranging from 5% to 60% by weight. This application leverages its ability to form highly conductive solutions, enhancing battery performance in demanding conditions. It can be used alone or in combination with cesium hydroxide, and occasionally mixed with smaller amounts of potassium or sodium hydroxide. Compared to more common electrolytes like or , rubidium hydroxide offers superior conductance and reduced in ionic hydration, which lowers the eutectic freezing point and improves activity coefficients. These properties enable more efficient operation at sub-zero temperatures, such as -50°C, where traditional KOH or NaOH electrolytes exhibit diminished capacity and efficiency. Its high solubility in further supports the formation of concentrated electrolytes suitable for such systems. RbOH exhibits proton conduction via a Grotthuss-type mechanism in its cubic high-temperature phase, contributing to high ionic mobility.

Safety

Toxicity and corrosivity

Rubidium hydroxide is highly corrosive due to its strong basic nature, causing severe burns upon contact with skin, eyes, and mucous membranes. Direct exposure to the skin can result in chemical burns, rash, or cold and clammy skin in milder cases, while eye contact leads to severe irritation, chemical conjunctivitis, and potential corneal damage. Inhalation of rubidium hydroxide dust or mist irritates the , potentially causing chemical burns, coughing, wheezing, , and in severe cases, or cardiac abnormalities. Ingestion poses significant dangers, including burns to the , mouth, throat, and esophagus, along with possible and systemic from absorption, though is relatively low except in large quantities. The compound is non-flammable and non-combustible but reacts exothermically with , generating significant that can cause the solution to boil and exacerbate burns from splashes or spills. Environmentally, releases of rubidium hydroxide can harm aquatic life through elevated levels in runoff or , leading to corrosive effects and potential of bodies.

Storage and handling

Rubidium hydroxide must be stored in tightly closed, airtight containers in a cool, dry, well-ventilated area designated for corrosives to prevent moisture absorption due to its hygroscopic nature. It should be kept away from incompatible materials, including strong acids and oxidizing agents, to avoid hazardous reactions. Handling requires trained personnel using appropriate , such as chemical-resistant gloves (e.g., ), safety goggles or a , protective clothing, and a NIOSH- or EN-approved respirator for dust or vapor exposure. Operations should occur in a well-ventilated space or under a , with hands washed thoroughly after handling and before breaks. stations and safety showers must be readily accessible. For spill response, evacuate non-protected personnel, ventilate the area, and avoid direct contact. Collect the material using dry methods, such as sweeping or absorbing with an inert material like , and transfer to sealed containers for disposal; do not use , as it can generate significant from the exothermic dissolution. Small spills may be neutralized cautiously with a dilute such as before absorption, but larger spills require professional hazardous materials response. Rubidium hydroxide is classified as a corrosive substance under transport regulations (Class 8), with 2678 for the solid form and 2677 for solutions, requiring Packing Group II and appropriate labeling for road, air, sea, and rail shipment. Disposal involves neutralization with a suitable acid under controlled conditions, followed by treatment as in accordance with local, regional, and national environmental regulations; incineration in a chemical incinerator with an and may be used for combustible mixtures. Contaminated containers should be disposed of similarly to the product.

References

  1. https://pubchem.ncbi.nlm.nih.gov/compound/Rubidium-hydroxide
  2. https://cameochemicals.noaa.gov/chemical/4417
  3. https://www.chemicalbook.com/ChemicalProductProperty_EN_CB4233581.htm
  4. https://www.americanelements.com/rubidium-hydroxide-1310-82-3
  5. https://www.webelements.com/compounds/rubidium/rubidium_hydroxide.html
  6. https://nanokar.com/rubidium-hydroxide/
  7. https://www.ck12.org/flexi/chemistry/strong-and-weak-bases-and-base-ionization-constant-kb/is-rboh-a-strong-base/
  8. https://www.webelements.com/rubidium/chemistry.html
  9. https://indico.cern.ch/event/548915/contributions/2225382/attachments/1305368/1951511/Rb_material_hazard_analysis_v0r3_Word_2003.pdf
  10. https://www.chemguide.co.uk/inorganic/group1/reacth2o.html
  11. https://en.sh-oujin.com/ProductShow.asp?ID=586
  12. https://pubs.usgs.gov/periodicals/mcs2025/mcs2025-rubidium.pdf
  13. https://srd.nist.gov/jpcrdreprint/1.555996.pdf
  14. https://doi.org/10.1016/j.micromeso.2012.09.006
  15. https://doi.org/10.1021/acscatal.5b00761
  16. https://patents.google.com/patent/US5840989A/en
  17. https://patents.google.com/patent/US2683102A/en
  18. https://www.sciencedirect.com/science/article/pii/0022459684901658
  19. https://pim-resources.coleparmer.com/sds/97218.pdf
  20. https://www.sigmaaldrich.com/IN/en/sds/aldrich/243892
  21. https://pubchem.ncbi.nlm.nih.gov/compound/62393
  22. https://www.nj.gov/health/eoh/rtkweb/documents/fs/1640.pdf
  23. https://www.sciencedirect.com/science/article/pii/0041008X75902161
  24. https://cameochemicals.noaa.gov/chemical/4418
  25. https://hhpprtv.ornl.gov/issue_papers/Rubidium.pdf
  26. https://www.fishersci.com/store/msds?partNumber=AA13481&productDescription=keyword&vendorId=VN00024248&countryCode=US&language=en
  27. https://www.sigmaaldrich.com/US/en/sds/aldrich/243892
  28. https://www.samaterials.com/pdf/Rubidium-Hydroxide-%28RbOH%29-sds.pdf
Add your contribution
Related Hubs
User Avatar
No comments yet.