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Boric acid



Name Boric acid
Chemical formula H3BO3
Appearance White solid


Formula weight 61.8 amu
Melting point Decomposes at 442 K (169 °C)
Density 1.4 ×103 kg/m3
Crystal structure ?
Solubility 5.7 g in 100g water


ΔfH0gas -992.28 kJ/mol
ΔfH0solid -1093.99 kJ/mol
S0gas, 1 bar 295.23 J/mol·K
S0solid 88.7 J/mol·K


Ingestion Toxic. Vomiting and diarrhea in small doses, larger doses may be fatal.
Inhalation May cause irritation.
Skin May cause irritation.
Eyes May cause irritation.
More info Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.

Disclaimer and references

Boric acid, also called boracic acid, is a chemical compound, a mild acid often used as an antiseptic, insecticide, flame retardant, and a component of other chemical compounds. It exists in the form of colorless crystals or a white powder and dissolves in water. It has the chemical formula H3BO3 and is known by the chemical name hydrogen orthoborate.

It can be used as an antiseptic only for minor burns or cuts and is sometimes used in dressings or salves or is applied in a very dilute solution as an eye wash. It is poisonous if taken internally or inhaled, although it is generally not considered to be much more toxic than table salt (based on its LD50 rating of 2660).

It is often used as a relatively nontoxic insecticide, for killing cockroaches, termites, fire ants, fleas, and many other insects. It can be used directly in powdered form for fleas and roaches, mixed with sugar for ants. It is also a component of many commercial insecticides.

Borates including boric acid have been used since the time of the Greekss for cleaning, preserving food, and other activites.

The largest source of borates in the world is an open-pit mine in Death Valley, California, USA.