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Borax

Borax chemical formula

Borax or borax powder chemical name sodium tetraborate decahydrate having chemical formula Na2B4O7, 10H2O, or Na2[B4O5(OH)4], 8H2O is used widely for the preparation of flux, glazes, and hard glass in India, Egypt, Rome, and other ancient civilizations. Borax is an important inorganic compound of the chemical element boron. It is isolated in 1808 by Sir Humphry Davy, Joseph Louis Gay-Lussac, and Louis Jacques Thenard

Heating of crystalline solid borax first swells due to losing the hydrated water but on further heating anhydrous substance gives meta-borate and boron trioxide. The physical properties or chemistry of borax are very similar to boric acid. It is obtained by heating boric acid solution with sodium carbonate.

Sodium tetraborate decahydrate structure

Borax powder, chemical name sodium tetraborate decahydrate, formula Na2[B4O5(OH)4] 8H2O structure and uses

Borax, commonly name sodium tetraborate decahydrate (Na2B4O7, 10H2O) has now written the formula Na2[B4O5(OH)4], 8H2O. The borax anion has two tetrahedral units of BO4 and two planners units of BO3 given above the picture. Each BO4 unit shares two oxygen with two planner BO3 units and one oxygen with the second BO4 unit. The fourth oxygen chemical bonding with the boron of the BO4 unit and a hydrogen atom. The planner BO3 unit is sp2 hybridized but the tetrahedral BO4 unit is sp3 hybridized. These hybrid orbital overlap with suitable orbitals of the oxygen and unpaired electrons.

Where borax can be found

Borax powder is an important chemical compound of boron found in pesticides or insecticides to killing ant or roach, antiseptics or mouthwash in medicine, cleaner solution or water softener, and enamel. It was first discovered in dry lake beds of 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 powder.

What is used in manufacture of borax

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

Properties of borax, Na2[B4O5(OH)4], 8H2O

The chemistry or properties and structure of boron compounds are very similar. Crystalline borax powder and boric acid are very much similar chemical properties. These chemicals are dissolved in liquid mainly hot water solution. At normal temperature, the crystalline borax powder contains ten molecules of hydrated water in its molecular formula.

At 62°C, it contains five molecules of hydrating water in its molecular structure. An aqueous solution shows alkaline properties due to hydrolysis. It reacts with water to form the substitute boric acid (H3BO3). It is a weak acid tritiated against strong acids using methyl orange as an indicator at pH scale 3.1 to 4.4).

Borax bead test reaction

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. It is used in chemistry for the quantitative chemical analysis of metal salts. This test is known as the borax bead test.

Borax bead test reaction and structure of metaborate ion in chemistry

Metaborate of transition metals

Metaborate 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. 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.

metaborate of metals bead test colour
oxidizing flame reducing flame
Copper green, blue dull red
Iron yellow dark green
Cobalt dark blue dark blue
Nickel brown colorless
Chromium green green

What is borax used for

  • A soft, light, colorless crystalline solid substance, sodium tetraborate decahydrate, or borax is used mainly in the manufacture of optical and hard glass.
  • It is used 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.
  • It is used in toxic poisonous pests or insecticide control chemicals for killing ants or roaches.
  • 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.