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Formula, Structure, Uses

Borax Powder Chemical Formula

Borax powder, chemical name sodium tetraborate decahydrate having chemical formula Na2B4O7, 10H2O, or Na2[B4O5(OH)4], 8H2O widely uses in India, Egypt, Rome, and other ancient civilization for the preparation of flux, glazes, and hard glass. Borax is an important chemical compound of the chemical element boron isolated in the nineteenth century by Sir Humphry Davy, Joseph Louis Gay-Lussac, and Louis Jacques Thenard in 1808. Heating of borax crystals first swells due to losing the hydrated water but on further heating anhydrous substance gives meta-borate and boron trioxide. The physical properties are of borax very similar to boric acid and obtained by heating boric acid solution with sodium carbonate.

Borax powder is an important chemical of boron compound widely uses in pesticide or insecticide to killing ant or roach, antiseptics or mouthwash in medicine, cleaner solution or water softener, and enamel or fertilizer preparation. It was first discovered in dry lake beds in Tibet and imported to Europe for refining. Turkey, California (Searles Lake), Southwestern United States, Chile (Atacama desert ), Bolivia, Tibet, and Romania is the most important commercial depositor or supplier of borax minerals.

Chemical Structure of Borax Crystal

Borax powder crystals or sodium tetra-borate decahydrate chemical formula and compound structure

The ionic structure of borax contains two covalent tetrahedral units of BO4 and two covalent planners units of BO3 and each BO4 shares two oxygen with two BO3 units but one oxygen with the second BO4 unit given below the picture. The fourth oxygen chemical bonding with the BO4 unit of boron and hydrogen atom. The planner BO3 unit is sp2 hybridized but the tetrahedral BO4 unit is sp3 hybridized with an additional electron from sodium. These hybrid orbital overlap with suitable orbitals of the oxygen atom.

Preparation of Sodium tetraborate decahydrate

Boiling the mineral colemanite with an alkaline solution of sodium carbonate uses for the preparation of sodium tetraborate decahydrate or crystalline solid borax powder. The produced calcium carbonate filtered out and concentration filtrate deposits as the crystals solid. Another solution containing NaBO2 again uses for the conversation of Na2B4O7, 10H2O by passing carbon dioxide (CO2). Borax is also obtained by chemical reaction or heating the boric acid solution with sodium carbonate and specific heat. It can be crystalline by cooling the solution.

Physical and Chemical Properties

The base properties and structure of boron compounds like crystalline borax powder and boric acid are very much similar that dissolved in liquid mainly hot water solution. At normal temperature, the crystalline borax powder contains ten molecules of hydrated water in its molecular formula but at 62°C, it contains five molecules of hydrating water in molecular structure. An aqueous solution shows alkaline properties due to hydrolysis. Because of the chemical reaction of water (H2O) with borax from the substitute boric acid (H3BO3), a weak acid tritiated against strong acids using methyl orange as an indicator (pH scale 3.1 to 4.4).

Color of Borax Bead Test in Chemistry

When we heating borax first swells due to the loss of hydrating water but further heating produced the chemical compounds metaborate and boron trioxide. The fusion of borax with metal oxides like copper, iron, cobalt, nickel, or chromium oxide forms a bead of metal borate that looks like a characteristic glossy color uses in chemistry for the quantitative chemical analysis of metal salts, known as the bead test. When it fusion with metal salts heated in oxidation flame forms ic-metaborate with a characteristic glossy color but when fusion with metal salts or heated in reduction flame forms us-metaborate with a characteristic glossy color.

Metal compound Color of the bead
Oxidizing flame Reducing flame
Copper Green, blue Dull red
Iron Yellow Dark green
Cobalt Dark blue Dark blue
Nickel Brown colorless
Chromium Green Green

The fusion of borax with metal ingredients like copper oxide (CuO) in an oxidizing flame defines blue cupric metaborate but in reducing flame it defines dull red cuprous metaborate.

Uses of Borax Powder

A soft, light, colorless crystalline solid substance, sodium tetraborate decahydrate, or borax is used mainly in the manufacture of optical and hard glass, as a solvent in metallurgy for metal-oxide slags, as a flux in welding and soldering, and as a fertilizer for the agricultural cultivation of food. Borax is also used as a soap supplement, as a carpet cleaner in the laundry, antiseptic in medicine, manufacturing of enamel for teeth, and toxic poisonous pest or insecticide control chemicals used for the killing ants or roach. Due to the facts of the low solubility of calcium and magnesium borates, borax is used as a cleaner or softener of water solution and preparation of glaze to pottery, stiffening candle-wicks, laundering, and cosmetics.