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. The broadly used term [|**lime**] connotes calcium-containing inorganic materials, in which carbonates, oxides and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate, such as [|limestone]. By contrast, **quicklime** specifically applies to a single chemical compound.



[|Calcium] [|oxide] is usually made by the thermal decomposition of materials such as [|limestone], that contain [|calcium carbonate] (CaCO3; mineral [|calcite]) in a [|lime kiln]. This is accomplished by heating the material to above 825 °C (1,517 °F),a process called [|calcination] or //lime-burning//, to liberate a molecule of [|carbon dioxide] (CO2); leaving quicklime. The quicklime is not stable and, when cooled, will [|spontaneously] react with CO2 from the air until, after enough time, it is completely converted back to calcium carbonate.