Calcium oxide
Molar mass: 56.08 g/mol · Class: Basic oxide
Elements: calcium, oxygen
Structure
Calcium oxide forms an ionic lattice of Ca2+ and O2- ions, similar to table salt's structure. The strong attraction between the doubly charged ions gives it a very high melting point.
Properties
White solid with a very high melting point (2613 °C)
Reacts exothermically with water to form calcium hydroxide
Basic oxide: reacts with acids to form salts
Absorbs carbon dioxide from air, reverting to calcium carbonate
Applications
Cement and mortar production
Steelmaking flux to remove impurities
Water treatment to adjust pH
Soil stabilization in construction
Corrosive solid: reacts with moisture on skin and eyes, causing burns. Dust irritates the respiratory tract. Wear goggles, gloves, and a dust mask; add to water carefully as the reaction releases heat.
Data source: IUPAC standard atomic weights 2021; molar mass computed from CaO