Sodium tetraborate pentahydrate

Chemical properties

Borax is a noncombustible (an inherent fire retardant), bluish-gray or green, odorless crystalline powder or granules.

General Description

White odorless crystals or free-flowing powder. Density: 1.82 g cm-3. Soluble in water (38 g / L H2O at 20°C). Used in the manufacture of fiberglass insulation and sodium perborate bleach.

Reactivity Profile

Sodium tetraborate pentahydrate is non-combustible. Dissolves somewhat exothermically in water to give basic solutions. Of generally low chemical reactivity. When heated in a closed tube, starts to melt in its own water of crystallization at 128°C and becomes fluid at 140°C. When heated in the open, loses water of crystallization and then melts at 742°C.

Hazard

A severe eye irritant.

Potential Exposure

Borax is used as a soldering flux, preservative against wood fungus; and as an antiseptic. Used in ant poisons, for fly control around refuse and manure piles, as a larvicide. It is used in the manufacture of enamels and glazes, fiberglass insulation; sodium perborate bleach; in tanning, cleaning compounds; for fireproofing fabrics and wood; and in artificial aging of wood.

Shipping

UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9—Miscellaneous hazardous material, Technical Name Required.

Incompatibilities

Dissolves in water forming a basic solution. Boron dust may form explosive mixture with air. Contact with strong oxidizers may be violent. Boron is incompatible with ammonia, bromine tetrafluoride, cesium carbide, chlorine, fluorine, interhalogens, iodic acid, lead dioxide, nitric acid, nitric oxide, nitrosyl fluoride, nitrous oxide, potassium nitrite, rubidium carbide, silver fluoride.

Waste Disposal

Borax, dehydrated: The material is diluted to the recommended provisional limit (0.10 mg/L) in water. The pH is adjusted to between 6.5 and 9.1 and then the material can be discharged into sewers or natural streams.