Borax Vs. Boric Acid

Borax and boric acid are both chemical compounds that contain the element boron. The chemical name for borax is sodium tetraborate decahydrate, and the molecular formula is B4Na2O7•10H2O. The molecular formula for boric acid is BH3O3. There are many similarities between borax and boric acid, such as appearance, toxicity, uses and even some physical properties.

Appearance

• Borax and boric acid are supplied as odorless, colorless, transparent crystals or white granules or powder.

Physical Properties

• Neither borax nor boric acid is combustible. The melting point of borax is 75 degrees C (167 degrees F), and the boiling point is 320 degrees C (608 degrees F). The melting point of boric acid is 169 degrees C (336 degrees F), and the boiling point is 300 degrees C (572 degrees F). It is possible to dissolve 6 g of borax into 100 mL of water at 20 degrees C (68 degrees F) and 4.7 g of boric acid in 100 mL of water at 20 degrees C (68 degrees F). Borax is also soluble in glycerol, but it is not soluble in ethanol or isopropanol (rubbing alcohol). Boric acid is soluble in methanol, ammonia, acetone, ethanol and glycerol. The pH of a 0.1 molar solution of boric acid is 5.1.

Toxicity

• Acute exposure to borax or boric acid by ingestion or absorption through injured or abraded skin can cause nausea, vomiting, diarrhea, a fall in body temperature, rash, headache, restlessness, weakness, kidney damage, circulatory collapse, shock and death. Chronic exposure to borax or boric acid by ingestion, skin absorption or absorption through mucous membranes can cause loss of appetite, weight loss, vomiting, diarrhea, rash, hair loss, convulsions and anemia.

  It is estimated that ingestion of 15 to 20 g of borax can be fatal. Ingestion of 5 to 20 g of boric acid can be fatal. Within the European Union, borax and boric acid are considered to be potential reproductive toxins that may impair fertility and cause harm to an unborn child.

Sources

• Borax occurs naturally as the minerals kernite, colemanite and tourmaline, which are mined and then refined into pure borax. Boric acid occurs naturally as the mineral sassolite.

Uses

• Borax is used to artificially age wood, to fireproof fabrics and wood, in soldering preparations, in glazes and enamels, for curing and preserving skins, in the manufacture of glass, in cleaning products, as a corrosion inhibitor in antifreeze, in adhesives, in metal alloys and to prevent mold on citrus.

  Boric acid is used to weatherproof wood, in the manufacture of cements, as a nuclear-reactor cooling water additive, as an insecticide, as a preservative, in welding flux, to impregnate wicks, in the manufacture of soap, in heat-resistant glass and in the manufacturing processes of other boron compounds.