What is borax?

Borax, commonly known as sodium tetraborate decahydrate has the chemical formula Na2B4O7, 10H2O or Na2[B4O5(OH)4], 8H2O. It is widely used in making optical, hard glass, antiseptic, and enamels. It is obtained by boiling mineral colemanite with sodium carbonate solution.

Structure of Borax

Structure and hybridization boron in borax
Image Source: borax chemical formula


The above picture shows that the structure of the borax anion or [B4O5(OH)4]-2 contains two tetrahedral BO4 units and two planner BO3 units. Each BO4 shares two oxygens with two planner BO3 and one oxygen with second BO4 units, The fourth oxygen is connected to the boron of the BO4 unit and hydrogen. The planner boron is sp2 hybridized and tetrahedral born is sp3 hybridized in borax structure.
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