User:Chemthulhu/sandbox
| Names | |
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| Other names
boric acid, lithium salt
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| EC Number |
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PubChem CID
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| Properties | |
| LiBO2 | |
| Molar mass | 49.751 g/mol |
| Appearance | white hygroscopic monoclinic crystals |
| Density | 2.223 g/cm3 |
| Melting point | 849 °C (1,560 °F; 1,122 K) |
| 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 (S⦵298) |
51.3 J/mol K |
Std enthalpy of
formation (ΔfH⦵298) |
-1022 kJ/mol |
Std enthalpy of
combustion (ΔcH⦵298) |
33.9 kJ/mol |
| Hazards | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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lithium metaborate (LiBO2) is a chemical compound.
Uses
[edit]Lithium metaborate is used as a general starting material to synthesize multiple analogs containing borate substituent and alkali metal coordination. The general reaction scheme involves combining: lithium carbonate, lithium hydroxide monohydrate or anhyd. lithium hydroxide, boric acid, and boron oxide, burning to obtain lithium metaborate, pulverizing to obtain lithium metaborate powder. To create analogs of lithium metaborate, the lithium metaborate powder requires substantial amounts of heat and reagent. An example for lithium metaborate with aluminum fluoride under vacuum obtains a high yield and quality. There are almost no side reactions and the reaction is environmentally friendly. The product lithium metaborate is a stable species.
Reactions
[edit]Catalytic Dehydrogenation
[edit]Catalytic dehydrogenation is a reaction that yields gas that bubbles from solution with a catalyst. The lithium metaborate acts as a highly efficient electron carrier when reacted with Magnesium Oxide to yield LiBH4 at 90% yields. The activation energy for such reaction was 33.12 kj/mol. The optimal reaction time is 1000 minutes reacting with the mole ratio of LiBO2 and MgO2 being 1.0.
Cytogenetic and Oxidative Alterations
[edit]Human and animal tissues are sensitive to boron containing compounds such as lithium metaborate dihydrate (LiBO2 ∙ 2 H2O, LMD); they contain antioxidant properties. LMD was applied to cultured red blood cells and the total oxidation was measured at varying concentrations at the microliter concentration. At lower concentrations the total oxidation was clear and varied less as more LMD was added. LMD has non-genotoxic effects and antioxidant potential in cells in vitro.
Applications
[edit]Lithium metaborate or lithium tetraborate (Li2B4O7), or a mixture of both, can be used in borate fusion sample preparation of various samples for spectroscopic analysis by XRF spectroscopy and AAS, ICP-OES, ICP-AES and ICP-MS.
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.[2]
Lithium metaborate dissolves acidic oxides such as SiO2 and Fe2O3, where the stoichiometric ratio of oxygen to cation, y/x in MxOy, is greater than unity. Lithium tetraborate dissolves basic oxides such as CaO, MgO and other oxides of the alkali metals and alkaline earth metals, where y/x ≤ 1. Most oxides are best dissolved in a mixture of the two lithium borate salts, for spectrochemical analysis.[3]
Borate Fusion
[edit]
Borate fusion is a sample preparation method that takes an oxidized sample (like Al2O3) and uses a flux whose purpose is to reduce the melting point of the oxidized sample and put it in a molten stage. Some solid sample may need the primary step of being oxidized, but it is common to find a powder-form oxidized metal sample. Once the oxidized sample is obtained it is placed into a platinum crucible with the desired flux and non wetting agent (compound whose purpose is to keep the molten mix from sticking to the crucible). Then the fusion is started and will reach on average 1000C. Claisse is a company that creates an automated fluxer like the M-4 Fusion Instrument. At this high temperature, the sample is melted and dissolved by the lithium borate flux to form a perfectly homogeneous mass. The molten mixture is then poured into aqua regia solution and stirred until the mixture dissolves for use in AA or ICP. An alternative endpoint of the borate fusion is to pour the molten mixture into a platinum mold to create a glass disk that can be used in XRF.
Mass Spectroscopy and Water Purity
[edit]A mass spectrometric method based on thermal ionization of lithium tetraborate has been developed for the isotopic analysis of lithium. The measurement of Li2BO2+ reduces isotopic fractioning during analysis compared to the normal use of Li+ ion. The technique is capable of achieving a relative precision of 1.3% in the determination of lithium isotopic ratios. A chemical procedure for quantitative and clean extraction of lithium from natural waters is described. This method has been applied to seawater with reproductivity within the analytical uncertainty. Preliminary study indicates this technique is also applicable to silicate rocks.
References
[edit]- ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 4–66, ISBN 0-8493-0594-2
- ^ Hettipathirana, T. D. (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. 59 (2): 223–229. doi:10.1016/j.sab.2003.12.013.
- ^ Fernand Claisse, "Fusion and fluxes," Comprehensive Analytical Chemistry: Sample Preparation for Trace Element Analysis, Vol. 41, Elsevier, 2003, p 301-311.
Category:Borates Category:Lithium compounds
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