Calcium Oxide CaO Lime

Calcium Oxide
Other Names: Lime, Quicklime, Burnt lime, Unslaked lime, Free lime (building), Caustic lime, Pebble lime, Calcia, Oxide of calcium

CAS Number: 1305-78-8
Sum Formula: CaO
Molar Mass: 56.08 g/mol
Appearance: White to pale gray, hard, granular or powdery solid

Calcium oxide is a highly caustic alkaline earth metal oxide produced by the thermal decomposition of limestone or other calcium-containing materials. It reacts exothermically with water to form calcium hydroxide and is widely utilized in chemical manufacturing, metallurgy, environmental treatment, and construction industries.

Chemical and Physical Properties
Density: 3.34 g/cm³
Melting Point: 2572°C
Boiling Point: 2850°C
Solubility in Water: Reacts with water, forming calcium hydroxide (slaking)
Solubility in Other Solvents: Insoluble in alcohol; reacts with acids
Odor: Odorless

Applications
Construction Industry: Used in the production of mortar, plaster, and cement by reacting with water.
Chemical Industry: Employed as a pH regulator, dehydrating agent, and reactant in chemical synthesis.
Metallurgy: Used as a flux to remove impurities (such as silica and phosphorus) from metal ores in steel production.
Environmental Engineering: Applied in flue gas treatment to capture sulfur dioxide and in wastewater neutralization.
Material Science: Incorporated into refractory materials and ceramics for high-temperature applications.

Safety

Signal Word: Danger

Handling and Storage
Storage Conditions: Store in a tightly closed container in a dry, well-ventilated area. Keep away from moisture and incompatible substances such as acids and organic materials.
Handling Precautions: Avoid inhalation of dust and direct contact with skin or eyes. Use standard PPE (gloves, goggles, protective clothing).