Borax
"Sodium borate" redirects here. For sodium perborate, see Sodium perborate.
Borax
IUPAC name[hide]
Sodium tetraborate decahydrate
Identifiers
CAS number (anhydrous) 1330-43-4 (anhydrous)
Identifiers
CAS number (decahydrate) 1303-96-4 (decahydrate)
Properties
Molecular formula Na2B4O7·10H2O or Na2[B4O5(OH)4]·8H2O
Molar mass 381.37
Appearance white solid
Density 1.73 g/cm³ (solid)
Melting point
743 °C[1]
Boiling point
1575 °C
Hazards
EU classification not listed
NFPA 704
010
Flash point Non-flammable
Related compounds
Other anions Sodium aluminate; sodium gallate
Other cations Potassium tetraborate
Related compounds Boric acid, sodium perborate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
Old steam tractor and Borax wagons, Death Valley
Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.
Borax has a wide variety of uses. It is a component of many detergents, cosmetics, and enamel glazes. It is also used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound for fiberglass, as an insecticide, as a flux in metallurgy, a texturing agent in cooking, and as a precursor for other boron compounds.
The term borax is used for a number of closely related minerals or chemical compounds that differ in their crystal water content, but usually refers to the decahydrate. Commercially sold borax is usually partially dehydrated.
The word borax is from Persian and originates in the Middle-Persian būrak.
