Sodium alum

Sodium aluminium sulfate is the inorganic compound with the chemical formula NaAl(SO₄)₂·12H₂O (sometimes written Na₂SO₄·Al₂(SO₄)₃·24H₂O). Also known as soda alum, sodium alum, or SAS, this white solid is used in the manufacture of baking powder and as a food additive. Its official mineral name is alum-Na (IMAsymbol: Aum-Na).