Quick lime

Quick lime:Calcium oxide

Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature.

Quicklime produces heat energy by the formation of the hydrate, calcium hydroxide, by the following equation:

CaO (s) + H2O (l) Ca(OH)2 (aq) (ΔHr = −63.7 kJ/mol of CaO)

When quicklime is heated to 2,400 °C (4,350 °F), it emits an intense glow. This form of illumination is known as a limelight, and was used broadly in theatrical productions prior to the invention of electric lighting.