Aluminum potassium sulfate dodecahydrate (KAl(SO4)2•12H2O)-Crystalline

Characteristic




Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound: the double sulfate of potassium and aluminium, with chemical formula KAl(SO4)2. It is commonly encountered as the dodecahydrate, KAl(SO4)2·12H2O. It crystallizes in cubic structure with space group P a -3 and lattice parameter of 12.18 Å. The compound is the most important member of the generic class of compounds called alums, and is often called simply alum.




Chemical formula:KAl(SO4)2·12H2O

Molar mass:258.192 g/mol (anhydrous);474.37 g/mol (dodecahydrate)

Appearance:White crystals

Odor:Watery metallic

Density:1.725 g/cm3

Melting point:92 to 95 °C (198 to 203 °F; 365 to 368 K)

Boiling point:200 °C (392 °F; 473 K)

Solubility in water:14.00 g/100 mL (20 °C);36.80 g/100 mL (50 °C)

Solubility in other solvents:Insoluble in acetone

Refractive index (nD):1.4564




Application




Potassium alum is commonly used in water purification, leather tanning, dyeing, fireproof textiles, and baking powder as E number E522. It also has cosmetic uses as a deodorant, as an aftershave treatment and as a styptic for minor bleeding from shaving.