calciumoxid

Calcium oxide, CaO, also known as quicklime or burnt lime, is a white, caustic alkaline oxide produced by calcination of calcium carbonate. It is a major chemical commodity used as a feedstock in cement and various chemical processes.

Preparation and properties: It is made by heating limestone or dolomite to about 900–1000°C, driving off carbon dioxide: CaCO3 → CaO + CO2. It readily hydrates: CaO + H2O → Ca(OH)2 (slaked lime), a highly exothermic reaction. CaO has a high melting point and low solubility in water but reacts vigorously with water to form calcium hydroxide, increasing the solution pH to around 12–13. In air, it slowly hydrates or carbonates to CaCO3, especially if moisture is present.

Applications: In cement and construction, lime is used as a clinker precursor or ground lime for mortars. It is used for soil stabilization and to raise soil pH in agriculture. In water treatment and mining, CaO neutralizes acidic water and acts as a general base. It is also used in flue gas desulfurization, paper, and chemical manufacturing; it serves as a drying agent and a reagent in various syntheses.

Safety: CaO is caustic and can cause severe burns on skin and eyes. It reacts with water to release heat and should be handled with appropriate PPE and stored in dry conditions away from moisture and acids.

Environmental notes: The production of CaO from CaCO3 releases CO2, contributing to greenhouse gas emissions; however, lime-based processes can also aid environmental remediation and pH control.

---