Na2B4O7OH2

Sodium tetraborate decahydrate, commonly known by its chemical formula Na₂B₄O₇·10H₂O, is a hydrated sodium borate compound. It is often referred to as borax or sodium borate decahydrate when in its crystalline form. This white, crystalline solid is widely recognized for its use in various household and industrial applications.

Borax forms when sodium oxide (Na₂O) reacts with boric anhydride (B₂O₃) in the presence of water. Its decahydrate form contains ten molecules of water per molecule of sodium tetraborate, which contributes to its solubility in water. The compound is stable under normal conditions but can lose water molecules upon heating, transitioning into anhydrous forms.

Historically, borax has been used as a cleaning agent, a water softener, and a component in detergents. It is also employed in the manufacture of fiberglass, as a flame retardant, and in the production of certain types of glass and ceramics. In laboratories, borax serves as a buffer in pH adjustments and a flux in metallurgy.

The compound exhibits mild alkaline properties due to the presence of hydroxide ions in its structure. When dissolved in water, it dissociates partially, releasing sodium and tetraborate ions, which can react with acids or other substances. Borax is generally considered safe for household use, though prolonged exposure to high concentrations may cause skin or eye irritation.

In addition to its practical uses, borax has been studied for its potential antimicrobial properties, though its effectiveness varies depending on concentration and application. It is also used in some traditional and alternative medicine practices, though scientific evidence supporting its efficacy in these contexts is limited. Proper handling and storage are recommended to avoid contamination or degradation.