Calcium oxide 1,Molecular formula: CaO 2,CAS: 1305-78-8 3,Appearance: White block or powder Properties:Colorless or white block or powder. In the air absorb carbon dioxide and water. The relative density of 320-3.38, melting point 2614 °C, boiling point 2850 °C. In water is generated with calcium hydroxide and give off a lot of heat, slightly soluble in water, soluble in acid. Corrosive. To eyes, ...