Calcium oxide
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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.
| Calcium oxide | |
|---|---|
| |
| |
| IUPAC name | Calcium oxide |
| Other names | Quicklime, burnt lime, unslaked lime, pebble lime, calcia |
| Identifiers | |
| CAS number | |
| PubChem | |
| ChEBI | CHEBI:31344 |
| RTECS number | EW3100000 |
| SMILES | [Ca]=O |
| Gmelin Reference | 485425 |
| Properties | |
| Molecular formula | CaO |
| Molar mass | 56.0774 g/mol |
| Appearance | White to pale yellow/brown powder |
| Odor | Odorless |
| Density | 3.34 g/cm3[1] |
| 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 | |
| Crystal structure | Cubic, cF8 |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−635 kJ·mol−1[2] |
| Standard molar entropy S |
40 J·mol−1·K−1[2] |
| Pharmacology | |
| ATC code | |
| Hazards | |
| NFPA 704 |
0
3
2
|
| Flash point | Non-flammable |
| U.S. Permissible exposure limit (PEL) |
TWA 5 mg/m3[3] |
| 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) | |
It is also a base. It reacts with acids to make calcium salts. Quicklime is an important ingredient of cement.
Calcium Oxide Media
A demonstration of slaking of quicklime as a strongly exothermic reaction. Drops of water are added to pieces of quicklime. After a while, a pronounced exothermic reaction occurs ('slaking of lime'). The temperature can reach up to some 300 °C (572 °F).
Related pages
References
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedcrc. - ↑ 2.0 2.1 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN 978-0-618-94690-7.
- ↑ NIOSH Pocket Guide to Chemical Hazards. "#0093". National Institute for Occupational Safety and Health (NIOSH).
