Overview

Calcium hydroxide (KAL-see-um hye-DROK-side) is a soft, white odorless solid that occurs as granules or a powder. It has a slightly bitter, alkaline taste. Calcium hydroxide absorbs carbon dioxide readily from the air, changing to calcium carbonate (CaCO₃). For this reason, the compound often is contaminated with the carbonate unless it is kept in tightly sealed containers. Calcium hydroxide is a relatively inexpensive chemical and, for that reason, is used in production processes where a base is needed. Although calcium hydroxide is not very soluble in water, a suspension of the finely divided powder in water can be made, a suspension known as limewater or milk of lime.

Key Facts

Other Names:

Calcium hydrate; caustic lime; hydated lime; slaked lime

Formula:

Ca(OH)₂

Elements:

Calcium, oxygen, hydrogen

Compound Type:

Inorganic base

State:

Solid

Molecular Weight:

74.09 g/mol

Melting Point:

Not applicable; loses water when heated...