Structure and Properties
Aluminium hydroxide exists naturally as the mineral gibbsite (also known as hydrargillite) and has three rarer polymorphs: bayerite, doyleite, and nordstrandite.
It is amphoteric, meaning it exhibits both basic and acidic properties.
The compound forms a gelatinous precipitate when dissolved in water.
Its chemical formula is Al(OH)₃, and its molar mass is approximately 78.003 g/mol.
Aluminium hydroxide appears as a white amorphous powder with a density of 2.42 g/cm³.
The melting point is 300°C (572°F; 573 K), and it is soluble in acids and alkalis.
Production and Uses
Aluminium hydroxide is a precursor to various aluminium compounds.
It serves as a filler and fire retardant in plastics, rubber, and other materials.
In pharmaceuticals, it is used as an antacid to neutralize excess stomach acid.
The compound also finds applications in water treatment and as a coagulant in wastewater treatment plants.
Aluminium hydroxide is commonly used in the production of aluminium metal from bauxite ore.
It plays a role in ceramics, catalysts, and flame retardants.
Safety
Aluminium hydroxide is generally safe, with no specific hazard statements.
It is non-flammable and has low toxicity.
The LD₅₀ (median lethal dose) for rats is greater than 5000 mg/kg when administered orally.
Safety precautions include avoiding inhalation and skin contact.
In summary, aluminium hydroxide is a versatile compound with applications in various fields. Its amphoteric nature and gelatinous properties make it valuable in both industrial and medical contexts. Remember to consult safety guidelines when handling this substance.