Trisodium borate is a chemical compound of sodium, boron, and oxygen, with formula Na3BO3, or (Na+)3[BO3]3−.[3] It is a sodium salt of the orthoboric acid B(OH)3.

Trisodium orthoborate
Names
IUPAC name
Trisodium orthoborate
Other names
  • Sodium, boric acid salt
  • Sodium orthoborate
  • Sodium borate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
117865
  • InChI=1S/BO3.3Na/c2-1(3)4;;;/q-3;3*+1 ☒N
    Key: BSVBQGMMJUBVOD-UHFFFAOYSA-N ☒N
  • B([O-])([O-])[O-].[Na+].[Na+].[Na+]
Properties
Na3BO3
Molar mass 127.78 g·mol−1
Density 1.73 g/cm3[1]
Melting point 75 °C (167 °F; 348 K) [1]
Boiling point 320 °C (608 °F; 593 K) [1]
Hazards
GHS labelling:[2]
GHS07: Exclamation markGHS08: Health hazard
Warning
H319, H360, H361d, H412
P203, P264+P265, P273, P280, P305+P351+P338, P318, P337+P317, P405, P501
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

The compound is also called trisodium orthoborate, sodium orthoborate, or just sodium borate. However, "sodium orthoborate" has been used also for a compound with formula Na4B2O5, which would correspond to an equimolar mixture of sodium metaborate NaBO2 and trisodium borate proper.[4] and "sodium borate" is sometimes used in the generic sense, for a sodium salt with any of several other borate anions.

Preparation

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Sodium carbonate Na2CO3 will react with sodium metaborate NaBO2 or boric oxide B2O3 to form the orthoborate and carbon dioxide when heated between 600 and 850 °C:[3]

NaBO2 + Na2CO3 → Na3BO3 + CO2

Difficult to obtain in pure form from melts.[5]

Properties

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Reactions

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When dissolved in water, the orthoborate anion partially hydrolyzes into metaborate [BO2] and hydroxide OH:[3]

[BO3]3− + H2O ⇌ [BO2] + 3 OH

Electrolysis of a solution of sodium orthoborate generates sodium perborate at the anode.[6] [7]

References

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  1. ^ a b c "Trisodium borate" Product page in the World Of Chemicals website. Accessed on 2022-06-27.
  2. ^ "Boric acid, sodium salt". pubchem.ncbi.nlm.nih.gov.
  3. ^ a b c Pasupathy Rajan Subbaiyan (2003): "Study of Trisodium Borate Formation and Its Reaction with Green Liquor in Partial Autocausticizing". Masters Thesis, Western Michigan University.
  4. ^ Daniel L. Calabretta and Boyd R. Davis (2007) "Investigation of the anhydrous molten Na–B–O–H system and the concept: Electrolytic hydriding of sodium boron oxide species". Journal of Power Sources, volume 164, issue 2, pages 782-791. doi:10.1016/j.jpowsour.2006.11.023
  5. ^ G. W. Morey and H. E. Merwin (1936): "Phase Equilibrium Relationships in the Binary System, Sodium Oxide-Boric Oxide, with Some Measurements of the Optical Properties of the Glasses". Journal of the American Chemical Society, volume 58, issue 11, pages 2248–2254. doi:10.1021/ja01302a04
  6. ^ Wilfrid Gustav Polack (1915): "The anodic behaviour of alkaline borate and perborate solutions". Transactions of the Faraday Society, volume 10, pages 177-196. doi:10.1039/TF9151000177
  7. ^ Tanatar (1898): Zh. Pys. Chem., volume 26, page 132.