Ammonium aluminium sulfate, also known as ammonium alum is a white crystalline double sulfate usually encountered as the dodecahydrate, formula NH₄Al(SO₄)₂·12H₂O. It is used in water purification, in vegetable glues, in porcelain cements, in natural deodorants and in tanning, dyeing and in fireproofing textiles.It is also an acidity regulator in its use as a food additive.

Properties

Chemical formula : NH₄Al(SO₄)₂·12H₂O

Molar mass : 453.33 g/mol

Appearance : white crystals

Density : 1.64 g/cm³

Melting point : 93.5 °C

Boiling point : 120 °C dehydr.

Solubility in water : 15 g/100 ml (20 °C)