Calcium oxide

Calcium oxide (CaO), commonly kent as quicklime or burnt lime, is a widely uised chemical compoond. It is a white, caustic, alkaline crystalline solit at ruim temperatur. The braid uised term "lime" connotes calcium-containin inorganic materials, that include carbonates, oxides an hydroxides o calcium, silicon, magnesium, aluminium, an airn predominate, lik limestone. Bi contrast, "quicklime" specifically applies tae a single chemical compoond.

Calcium oxide

Names
IUPAC name Calcium oxide
Ither names Quicklime, burnt lime, unslaked lime
Identifiers
CAS Nummer	1305-78-8 N
3D model (JSmol)	Interactive eemage
ChemSpider	14095
PubChem CID	14778
RTECS nummer	EW3100000
UNII	C7X2M0VVNH
UN nummer	1910
InChI InChI=1/Ca.O/rCaO/c1-2 Key: ODINCKMPIJJUCX-BFMVISLHAU
SMILES [Ca]=O
Properties
Chemical formula	CaO
Molar mass	56.0774 g/mol
Appearance	White tae fauch yellae/broun pouder
Odour	odorless
Density	3.34 g/cm3[1]
Meltin pynt	2613 °C, 2886 K, 4735 °F[1]
Bylin pynt	2850 °C, 3123 K (100 hPa)[2]
Solubility in watter	1.19 g/L (25 °C), 0.57 g/L (100 °C), exothermic reaction[3]
Solubility in acids	soluble (an aa in glycerol, succar solution)
Solubility in methanol	insoluble (an aa in diethyl ether, n-octanol)
Acidity (pKa)	12.8
Thermochemistry
Staundart molar entropy So298	40 J·mol−1·K−1[4]
Std enthalpy o formation ΔfHo298	−635 kJ·mol−1[4]
Hazards
NFPA 704	0 3 2
Flash pynt	Non-flammable
Relatit compoonds
Ither anions	Calcium sulfide Calcium hydroxide
Ither cations	Beryllium oxide Magnesium oxide Strontium oxide Barium oxide
Except whaur itherwise notit, data are gien for materials in thair staundart state (at 25 °C [77 °F], 100 kPa).
Infobox references

Quicklime is relatively inexpensive. Baith it an a chemical derivative (calcium hydroxide) is important commodity chemicals.