Calcium oxide (CaO), commonly known as quicklime, is a white, caustic, and alkaline crystalline solid widely used in industrial, construction, and environmental applications. Produced through the thermal decomposition of limestone (CaCO₃) in a lime kiln at temperatures above 900°C, calcium oxide releases carbon dioxide and transforms into its reactive form.
One of its most notable properties is its exothermic reaction with water, producing calcium hydroxide (slaked lime) and significant heat. This reactivity makes it invaluable in processes requiring pH adjustment, moisture absorption, or chemical synthesis.
Calcium oxide is non-combustible, but due to its caustic nature, it requires careful handling to avoid chemical burns and respiratory irritation. It has a melting point of around 2,572°C and a density of approximately 3.34 g/cm³.
Its ability to neutralize acids, absorb water, and act as a flux in metallurgical processes ensures that calcium oxide remains a staple in industries ranging from steel manufacturing to water treatment.