Overview

Aluminum potassium sulfate (uh-LOO-min-um po-TASS-see-um sul-fate) is also known as aluminum potassium sulfate dodecahydrate, potash alum, potassium alum, and kalinite. It normally occurs in the form of the dodecahydrate, meaning that each molecule of the compound is associated with twelve molecules of water. The formula of the hydrate is KAl(SO₄)₂·12H₂O. In this form, it occurs as white odorless crystals. The compound gradually loses its water of hydration when heated, giving up the first nine molecules of water at 64.5°C (148°F), and the remaining three molecules of water at about 200°C (392°F).

Key Facts

Other Names:

See Overview.

Formula:

KAl(SO₄)₂

Elements:

Potassium, aluminum, sulfur, oxygen

Compound Type:

Inorganic salt

State:

Solid

Molecular Weight:

258.20 g/mol

Melting Point:

92.5°C (198°F; loses water of hydration beginning at 64.5°C (148°F)

Boiling Point:

200°C (392°F; loses all water of hydration)

Solubility:

Soluble in cold...