Calcium oxide |
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IUPAC name | Calcium oxide |
Other names | Quicklime, burnt lime, unslaked lime, pebble lime, calcia |
Identifiers |
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CAS number | 1305-78-8 |
PubChem | 14778 |
ChEBI | CHEBI:31344 |
RTECS number | EW3100000 |
SMILES | [Ca]=O |
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Gmelin Reference | 485425 |
Properties |
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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 | |
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 |
Structure |
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Crystal structure | Cubic, cF8 |
Thermochemistry |
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Std enthalpy of formation ΔfHo298 | −635 kJ·mol−1 |
Standard molar entropy So298 | 40 J·mol−1·K−1 |
Pharmacology |
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ATC code | |
Hazards |
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NFPA 704 | |
Flash point | Non-flammable |
U.S. Permissible exposure limit (PEL) | TWA 5 mg/m3 |
Related compounds |
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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) |