Calcium oxide

Calcium oxide
Calcium oxide
Names
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
RTECS number
  • EW3100000
UNII
UN number 1910
  • [Ca]=O
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 ΔfHo298		 −635 kJ·mol−1
Standard molar
entropy So298		 40 J·mol−1·K−1
Pharmacology
QP53AX18 (WHO)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
0
2
W
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 5 mg/m3
REL (Recommended)
 TWA 2 mg/m3
IDLH (Immediate danger)
 25 mg/m3
Safety data sheet (SDS) Hazard.com
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

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.

References

  1. 1 2 Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.55. ISBN 1439855110.
  2. ↑ Calciumoxid Archived 2013-12-30 at the Wayback Machine. GESTIS database
  3. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN 978-0-618-94690-7.
  4. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0093". National Institute for Occupational Safety and Health (NIOSH).