Products
Calcium oxide is available as a pure substance in pharmacies and drugstores.
Structure and properties
Calcium oxide (CaO, Mr = 56.08 g/mol) is the basic oxide of calcium. It exists as a white and odorless powder and reacts strongly with water (see below). It should therefore be stored away from moisture. It can be obtained, for example, from calcium carbonate (lime) or from limestone by heating at over 825°C.
- CaCO3 (calcium carbonate) CaO (calcium oxide) + CO2 (carbon dioxide)
Due to the production with heat, calcium oxide is also called burnt lime. Calcium hydroxide, which is made with water from calcium oxide, is called slaked lime. Calcium hydroxide is formed when water is added. This reaction is strongly exothermic:
- CaO (calcium oxide) + H2O (water) Ca(OH)2 (calcium hydroxide) + energy (heat).
Effects
Calcium oxide has strong corrosive, irritant, basic and antiseptic properties.
Fields of application
Fields of application include (selection):
- As a food additive, including as an acidity regulator (E 529).
- As a base.
- For the preparation of calcium hydroxide.
- For chemistry experiments: Preparation from calcium carbonate, reaction with water, Drummond light at high heating, bonding of carbon dioxide with calcium hydroxide.
Adverse effects
Calcium oxide can cause severe irritation to the skin, respiratory tract and severe eye irritation and damage if handled improperly. The appropriate precautions in the safety data sheet must therefore be observed (e.g. wearing safety glasses, protective clothing and gloves).
