Methods of Preparing Boric Acid, Properties and Applications

Boric acid is a very weak acid with the formula H3BO3. Boric acid aka boracic acid or arthoboric acid frequently used as a mild antiseptic in the medical field. As a chemical compound, Boric acid acts as a tribasic acid. However, because it dissociates to such a small extent, it is a very weak acid that is actually used in water solution as an eye wash. Pure boric acid is a colorless, odorless, white powder or transparent crystals with a slightly oily feeling that slowly decomposes with heat at about 340°F (171°C).

Boric acid loses water as it is heated, changing first into metaboric acid (HBO2) and then into pyroboric acid (H2B4O7) and eventually to boric oxide (B2O3). The three acids can be thought of as hydrates of boric oxide (B2O3). Orthoboric acid is fairly soluble in water (especially hot water), alcohol, and glycerine.

Properties of Boric Acid

Boric acid is a white solid that crystallizes from aqueous solutions as triclinic waxy plates. The crystal structure of boric acid consists of planar sheets of planar trigonal B(OH)3 molecules linked by hydrogen bonds.

Applications of Boric Acid in Our Daily Life

Boric acid has a wide applications in our daily life. The most important uses of Boric acid is as a source of B2O3 in glasses and other vitreous products, fiberglass, heat-resistant borosilicate glasses, ceramic glazes, porcelain, ceramics, crockery, enamels, artificial gemstones, and sealing and optical glasses. Boric acid has other applications like insecticide for cockroaches, black carpet beetles and as an fungicide on citrus fruits.

In the medical field, boric acid has extensive use in mouthwashes, nasal sprays, and eye-hygiene formulations. Boric acid can also be used as a fire-retardant in some occasions. Other important applications include preservatives for natural products such as wood and natural fibers.

Availability of Boric Acid In Nature

In nature, Boric acid exists in two forms, a glassy form obtained by high temperature dehydration of boric acid, and crystalline form obtained by slow heating of metaboric acid. Boric acid occurs naturally in a number of locations where it has precipitated out of hot springs. It may occur then in the form of the mineral sassolite.

Production of Boric Acid

Boric Acid powder
Boric Acid powder - H3BO3

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The most common method of producing boric acid is by treating the relatively abundant borax with hydrochloric or sulfuric acid and crystallizing out the boric acid that forms in the reaction.

A less common method of preparation involves the treatment of borax brine solutions with a chelating agent that binds to the borates present in the brine, which can then be converted to boric acid.

Boric acid can be prepared in the laboratory by acid hydrolysis of a variety of boron compounds, including halides, esters, salts, and hydrides.

Boric acid is produced commercially by reactions of sulfuric acid with sodium borates, and with sodium and calcium borates or by reaction of sulfuric acid with ulexite, a mixed sodium-calcium borate. Boric acid is also produced from the borosilicate mineral datolite.

Fact of Boric Acid

  • Different Names of Boric Acid

    Orthoboric acid, Hydrogen orthoborate, Boracic acid

  • Formula of Boric Acid


  • Elements of Boric Acid

    Hydrogen, boron, oxygen

  • Compound Type of Boric Acid

    Inorganic acid

  • Physical State od Boric Accid


  • Molecular Weight of Boric Acid

    61.83 g/mol

  • Melting Point of Boric Acid

    170.9C (339.6F)

  • Boiling Point of Boric Acid

    Decomposes above its melting point

  • Solubility of Boric Acid

    Soluble in water, ethyl alcohol, and glycerol

  • Toxicity of Boric Acid

    Boric acid is toxic if swallowed