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Lithium metaborate

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Lithium metaborate
Names
Other names boric acid, lithium salt
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.287 Edit this at Wikidata
EC Number
  • 236-631-5
PubChem CID
CompTox Dashboard (EPA)
InChI
  • InChI=1S/BO2.Li/c2-1-3;/q-1;+1Key: HZRMTWQRDMYLNW-UHFFFAOYSA-N
  • InChI=1/BO2.Li/c2-1-3;/q-1;+1Key: HZRMTWQRDMYLNW-UHFFFAOYAF
SMILES
  • .B=O
Properties
Chemical formula LiBO2
Molar mass 49.751 g/mol
Appearance white hygroscopic monoclinic crystals
Density 2.223 g/cm
Melting point 849 °C (1,560 °F; 1,122 K)
Solubility in water 0.89 g/100 mL (0 °C)
2.57 g/100 mL (20 °C)
11.8 g/100 mL (80 °C)
Solubility soluble in ethanol
Thermochemistry
Heat capacity (C) 59.8 J/mol K
Std molar
entropy (S298) 		51.3 J/mol K
Std enthalpy of
formation (ΔfH298) 		-1022 kJ/mol
Std enthalpy of
combustion (ΔcH298) 		33.9 kJ/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2 0 0
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Lithium metaborate is a chemical compound of lithium, boron, and oxygen with elemental formula LiBO2. It is often encountered as a hydrate, LiBO2·nH2O, where n is usually 2 or 4. However, these formulas do not describe the actual structure of the solids.

Lithium metaborate is one of the borates, a large family of salts (ionic compounds) with anions consisting of boron, oxygen, and hydrogen.

Structure

Lithium metaborate has several crystal forms.

The α form consists of infinite chains of trigonal planar metaborate anions [BO2O]n.

The γ form is stable at 15 kbar and 950 °C. It has a polymeric cation consisting of a tridimensional regular array of [B(O−)4] tetrahedra sharing oxygen vertices, alernating with lithium cations, each also surrounded by four oxygen atoms. The B-O distances are 148.3 pm, the Li-O distances are 196 pm.

Lithium metaborate forms glass relatively easily, and consists of approximately 40% tetrahedral borate anions, and 60% trigonal planar boron. The ratio of tetrahedral to trigonal boron has been shown to be strongly temperature dependent in the liquid and supercooled liquid state.

Applications

Laboratory

Fusion flux consisting of lithium metaborate and lithium teraborate, with a small amount of lithium bromide.

Molten lithium metaborate, often mixed with lithium tetraborate Li2B4O7, is used to dissolve oxide samples for analysis by XRF, AAS, ICP-OES, ICP-AES, and ICP-MS, modern versions of classical bead test. The process may be used also to facilitate the dissolution of oxides in acids for wet analysis. Small amounts of lithium bromide LiBr or lithium iodide LiI may be added as mold and crucible release agents.

Lithium metaborate dissolves acidic oxides MexOy with x < y, such as SiO2 Al2O3, SO3, P2O5, TiO2, Sb2O3, V2O5, WO3, and Fe2O3. Lithium tetraborate, on the other hand, dissolves basic oxides with x > y, such as CaO, MgO and other oxides of the alkali metals and alkaline earth metals. Most oxides are best dissolved in a mixture of the two lithium borate salts, for spectrochemical analysis.

References

  1. David R. Lide (1998): Handbook of Chemistry and Physics, edition 87, pages 4–66. CRC Press. ISBN 0-8493-0594-2
  2. M. Marezio and J. P. Remeika (1966): "Polymorphism of LiMO2 Compounds and High‐Pressure Single‐Crystal Synthesis of LiBO2". Journal of Chemical Physics, volume 44, issue 9, pages 3348-. doi:10.1063/1.1727236
  3. Alderman, Oliver; Benmore, Chris; Weber, Rick (2020). "Consequences of sp2–sp3 boron isomerization in supercooled liquid borates". Applied Physics Letters. 117 (13): 131901. doi:10.1063/5.0024457.
  4. Alderman, Oliver; Benmore, Chris; Reynolds, Bryce; Royle, Brock; Feller, Steve; Weber, Rick (2023). "Liquid fragility maximum in lithium borate glass-forming melts related to the local structure". International Journal of Applied Glass Science. 14: 52–68. doi:10.1111/ijag.16611.
  5. Terrance D. Hettipathirana (2004): "Simultaneous determination of parts-per-million level Cr, As, Cd and Pb, and major elements in low level contaminated soils using borate fusion and energy dispersive X-ray fluorescence spectrometry with polarized excitation". Spectrochimica Acta Part B: Atomic Spectroscopy, volume 59, issue 2, pages 223-229. doi:10.1016/j.sab.2003.12.013
  6. ^ Fernand Claisse (2003): "Fusion and fluxes". Comprehensive Analytical Chemistry: Sample Preparation for Trace Element Analysis, volume 41, pages 301-311.
Lithium compounds (list)
Inorganic (list)
Organic (soaps)
Minerals
Hypothetical
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