Calcium Oxide, CaO

Calcium Oxide, CaO

Calcium Oxide, CaO
Calcium Oxide or Quick Lime is prepared on a commercial scale by heating limestone (CaCO3) in a rotary kiln at 1070-1270 K.
The carbon dioxide is removed as soon as it is produced to enable the reaction to proceed to completion.

Calcium Oxide or Quick Lime is a white amorphous solid. It has a melting point of 2870 K. On exposure to atmosphere; it absorbs moisture and carbon dioxide.

CaO  +  H2O   →   Ca(OH)2
CaO  +  CO2   →   CaCO3

The addition of limited amount of water breaks the lump of lime. This process is called slaking of lime. Quick lime slaked with soda gives solid sodalime. Being a basic oxide, it combines with acidic oxides at high temperature.

CaO  +  SiO2   →   CaSiO3
6CaO  +  P4O10   →   2Ca3(PO4)2


  • It is an important primary material for manufacturing cement and is the cheapest form of alkali.
  • It is used in the manufacture of sodium carbonate from caustic soda.
  • It is employed in the purification of sugar and in the manufacture of dye stuffs.


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