boric acid


Also found in: Dictionary, Thesaurus, Medical, Legal, Acronyms, Wikipedia.

boric acid,

any one of the three chemical compounds, orthoboric (or boracic) acid, metaboric acid, and tetraboric (or pyroboric) acid; the term often refers simply to orthoboric acid. The acids may be thought of as hydrates of boric oxide, B2O3. Orthoboric acid, H3BO3 or B2O3·3H2O, is colorless, weakly acidic, and forms triclinic crystals. It is fairly soluble in boiling water (about 27% by weight) but less so in cold water (about 6% by weight at room temperature). When orthoboric acid is heated above 170°C; it dehydrates, forming metaboric acid, HBO2 or B2O3·H2O. Metaboric acid is a white, cubic crystalline solid and is only slightly soluble in water. It melts at about 236°C;, and when heated above about 300°C; further dehydrates, forming tetraboric acid, H4B4O7 or B2O3·H2O. Tetraboric acid is either a vitreous solid or a white powder and is water soluble. When tetraboric or metaboric acid is dissolved it reverts largely to orthoboric acid. The major uses of the boric acids are in forming other boron compounds and in borate salts, e.g., boraxborax
or sodium tetraborate decahydrate
, chemical compound, Na2B4O7·10H2O; sp. gr. 1.73; slightly soluble in cold water; very soluble in hot water; insoluble in acids.
..... Click the link for more information.
. A dilute water solution of boric acid is commonly used as a mild antiseptic and eyewash. Boric acid is also used in leather manufacture, electroplating, and cosmetics. Boric acid can be crystallized from an acidified borax solution. It occurs as the mineral sassolite in the Tuscan region of Italy, where it is also recovered from hot springs and vapors. In the United States boric acid is recovered from brines from Searles Lake in California.

Boric Acid

 

(also orthoboric acid), H3BO3, a weak inorganic tribasic acid; colorless crystals in the form of flakes. Density, 1.48 g/cm3. Moderately soluble in cold water and more soluble in hot water, which is used to purify it (solubility per 100 g H2O: 2.66 g at 0° C; 39.7 g at 100° C). Boric acid is soluble in alcohol and other organic substances. When heated it loses water, turning first into metaboric acid, HBO2, and then into boric anhydride, B2O3. The salts of boric acid—borates—are derived mainly from various polyboric acids with the general formula nB2O3 · mH2O. When boric acid reacts with alcohols in the presence of concentrated H2SO4 (for bonding water), esters—for example, boric methyl ester—are formed:

3CH3OH + H3BO3 = B(OCH3)3 + 3H2O

When ignited, the esters of boric acid burn with a green flame, which is a qualitative reaction for boron. Boric acid is found in nature in hot springs as a dissolved form and as vapor. It evolves in the form of the mineral sassolite from hot springs and excrustations in volcanic craters. The industrial significance of natural boric acid is relatively small; it is usually obtained during the processing of borates.

Large quantities of boric acid are used to produce enamel wares. In laboratory practice boric acid is used in the preparation of buffer systems. In medicine it is used as an antiseptic. Aqueous solutions of boric acid serve as mouth and throat rinses and eyewashes. Ointments, pastes, and powders with boric acid and boric alcohol (boric acid dissolved in alcohol) are administered for some skin diseases (boric alcohol is also prescribed as ear drops). Boric acid is an ingredient in contraceptives.

V. L. VASILEVSKII

boric acid

[¦bȯr·ik ′as·əd]
(inorganic chemistry)
H3BO3 An acid derived from boric oxide in the form of white, triclinic crystals, melting at 185°C, soluble in water. Also known as boracic acid; orthoboric acid.

boric acid

1. a white soluble weakly acid crystalline solid used in the manufacture of heat-resistant glass and porcelain enamels, as a fireproofing material, and as a mild antiseptic. Formula: H3BO3
2. any other acid containing boron
References in periodicals archive ?
2006, 2008), who found > 80% mortality in the application of boric acid to vegetation against a laboratory-reared population of Ae.
5 mo * Tympanoplasty * These 4 patients received CCAH (ciprofloxacin, chloramphenicol, amphotericin, and hydrocortisone) powder; the other 7 patients received boric acid powder, nystatin powder, and oral fluconazole Key: EAC = external auditory canal; TM = tympanic membrane; PCP = primary care physician; OE = otitis externa; ENT = otolaryngologist.
Four chemicals (Ethanolamine, Chloroparaffin, Neodecanoic Acid and Sodium Palmitate) had metal concentrations greater than 50 ppm at both concentrations but only at the high temperature, and three chemicals (Sodium Gluconate, Boric Acid and Calcium Alkyl Aryl Sulfonate) had concentrations greater than 50 ppm only at the high concentration and high temperature.
Japanese authorities have poured boric acid and seawater into the reactors in a last-ditch effort to cool the reactors following a series of explosions at the stricken plant.
The percentage of total sugars was low in the fruits treated with calcium chloride and boric acid.
Key words: Corynebacterium kroppenstedtii, otitis externa, acetic and boric acid solution, avian, peach-faced lovebird, Agapornis roseicollis
Al Abruzzese, owner of the website Al's Home Improvement Center, swears by boric acid to get rid of wood-boring pests.
He found was surrounded by and laying on boric acid, used to kill roaches.
The other 3% was decomposed materials including boric acid, borates, hydrogen, and dimethylamine (DMA).
A carton of orange juice contained hydraulic fluid, Boric acid was found in a jar of horseradish and a bottle of babyfood, and a jar of carrots contained shards of glass.