Overview

Sodium tetraborate (SO-dee-um tet-ruh-BOR-ate) is a term used for either the anhydrous or hydrated form of the compound with the formula Na₂B₄O₇. The decahydrate (Na₂B₄O₇·10H₂O) is also referred to as borax. Borax also occurs without water of hydration and in that form is known as anhydrous borax.

Key Facts

Other Names:

Sodium borate; sodium pyroborate; disodium tetraborate; borax

Formula:

Na₂B₄O₇ or Na₂B₄O₇·10H₂O; see Overview

Elements:

Sodium, boron, oxygen

Compound Type:

Salt (inorganic)

State:

Solid

Molecular Weight:

Na₂B₄O₇: 201.22 g/mol; Na₂B₄O₇·10H₂O: 381.37 g/mol

Melting Point:

Na₂B₄O₇: 743°C (1370°F); Na₂B₄O₇·10H₂O: decomposes at about 75°C (170°F)

Boiling Point:

Na₂B₄O₇: 1575°C (2867°F); Na₂B₄O₇·10H₂O: not applicable

Solubility:

Soluble in water

Some historians think that borax may have been known as...