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Calcium oxide
Oxid vápenatý.PNG
Calcium oxide.JPG
IUPAC name Calcium oxide
Other names Quicklime, burnt lime, unslaked lime, pebble lime, calcia
CAS number 1305-78-8
PubChem 14778
RTECS number EW3100000
Gmelin Reference 485425
Molecular formula CaO
Molar mass 56.0774 g/mol
Appearance White to pale yellow/brown powder
Odor Odorless
Density 3.34 g/cm3
Melting point

2613 °C, 2886 K, 4735 °F

Boiling point

2850 °C, 3123 K, 5162 °F

Solubility in water Reacts to form calcium hydroxide
Solubility in Methanol Insoluble (also in diethyl ether, octanol)
Acidity (pKa) 12.8
−15.0×10−6 cm3/mol
Crystal structure Cubic, cF8
Std enthalpy of
formation ΔfHo298
−635 kJ·mol−1
Standard molar
entropy So298
40 J·mol−1·K−1
ATC code
NFPA 704

NFPA 704.svg

Flash point Non-flammable
U.S. Permissible
exposure limit (PEL)
TWA 5 mg/m3
Related compounds
Other anions Calcium sulfide
Calcium hydroxide
Other cations Beryllium oxide
Magnesium oxide
Strontium oxide
Barium oxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Calcium oxide is a chemical compound of calcium and oxygen. Its chemical formula is CaO. It is known as quicklime. It is made in a lime kiln. It releases heat when dissolved in water and changes into calcium hydroxide. It is a white powder.

It is also a base. It reacts with acids to make calcium salts. Quicklime is an important ingredient of cement.

Related pages

See also

Kids robot.svg In Spanish: Óxido de calcio para niños

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