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.
Names | ||
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IUPAC name Calcium oxide | ||
Other names Quicklime, burnt lime, unslaked lime, pebble lime, calcia | ||
Identifiers | ||
3D model (JSmol) | ||
ChEBI | ||
ChEMBL | ||
ChemSpider | ||
ECHA InfoCard | 100.013.763 | |
E number | E529 (acidity regulators, ...) | |
Gmelin Reference | 485425 | |
PubChem CID | ||
RTECS number |
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UNII | ||
UN number | 1910 | |
CompTox Dashboard (EPA) | ||
SMILES
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Properties | ||
CaO | ||
Molar mass | 56.0774 g/mol | |
Appearance | White to pale yellow/brown powder | |
Odor | Odorless | |
Density | 3.34 g/cm3 | |
Melting point | 2,613 °C (4,735 °F; 2,886 K) | |
Boiling point | 2,850 °C (5,160 °F; 3,120 K) (100 hPa) | |
Reacts to form calcium hydroxide | ||
Solubility in Methanol | Insoluble (also in diethyl ether, octanol) | |
Acidity (pKa) | 12.8 | |
−15.0×10−6 cm3/mol | ||
Structure | ||
Cubic, cF8 | ||
Thermochemistry | ||
Std enthalpy of formation ΔfH | −635 kJ·mol−1 | |
Standard molar entropy S | 40 J·mol−1·K−1 | |
Pharmacology | ||
ATCvet code | QP53AX18 (WHO) | |
Hazards | ||
NFPA 704 | | |
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 otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | ||
Infobox references | ||
It is also a base. It reacts with acids to make calcium salts. Quicklime is an important ingredient of cement.
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