Calcium Oxide (CaO), commonly known as Quicklime or Burnt Lime or Unslaked Lime or Pebble Lime or Calcia
CaCO3 (s) + Heat ⟶ CaO(s) + CO2(g)
Calcium Oxide is made by the thermal decomposition of Limestone / Lime Powder that contain Calcium Carbonate (CaCO3 ; mineral calcite) in a Lime Kiln. This is accomplished by heating the material to above 950°C, a process called calcination or lime burning to liberate a molecule of carbon dioxide (CO2), leaving Quicklime.
| IUPAC name | Calcium oxide |
| Other names | Quicklime, burnt lime, unslaked lime, pebble lime, calcia |
| Chemical formula | 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) |
| Solubility in water | Reacts to form calcium hydroxide |
| Solubility in Methanol | Insoluble (also in diethyl ether, octanol) |
| Acidity (pKa) | 12.8 |
| Magnetic susceptibility (χ) | −15.0×10−6 cm3/mol |
| Crystal structure | Cubic, cF8 |
Because of vigorous reaction of quicklime with water, quicklime causes severe irritation when inhaled or placed in contact with moist skin or eyes. Inhalation may cause coughing, sneezing, and labored breathing. It may then evolve into burns with perforation of the nasal septum, abdominal pain, nausea and vomiting. Although quicklime is not considered a fire hazard, its reaction with water can release enough heat to ignite combustible materials.
Did you know?
Limestone is composed of the mineral calcite (calcium carbonate) and/or the mineral dolomite (calcium and magnesium carbonate) along with small amounts of other minerals.