from colemanite ore by boiling its solution with sodium carbonate. 2Ca B O + 3Na CO + H O Δ 3Na B O + 3CaCO + Ca(OH) - - - - Borax is normally formulated as Na B O .10H O. But it contains, tetranuclear units [B O . (OH) ] - .
This form is known as prismatic form. Borax also exists two other forms namely, jeweller or octahderal borax (Na B O .5H O) and borax glass (Na B O ). Properties Borax is basic in nature and its solution in hot-water is alkaline as it dissociates into boric acid and sodium hydroxide. Na B O + 7H O 4H BO + 2NaOH On heating it forms a transparent borax beads.
Na B O .10H O Δ Na B O -10H O 2NaBO + B O Borax reacts with acids to form sparingly soluble boric acid. Na B O + 2HCl + 5H O 4H BO + 2NaCl Na B O + H SO + 5H O 4H BO + Na SO When treated with ammonium chloride it forms boron nitride. Na B O + 2NH Cl 2NaCl + 2BN + B O + 4H O Uses of Borax: . Borax is used for the identification of coloured metal ions .
In the manufacture optical and borosilicate glass, enamels and glazes for pottery . It is also used as a flux in metallurgy and also acts as a preservative . . .
Boric acid [H BO or B(OH) ]: Preparation: Boric acid can be extracted from borax and colemanite. Na B O + H SO + 5H O 4H BO