Calcium Oxide (CaO)

Preparation : It is commonly called quick lime and made by decomposing line stone at a high temperature about 1000"C. CaCO3 --> CaO + CO2 + 42000 cal. Chemical properties : 1. It is white amorphous powder of m.p 2570 c. On exposure to atmosphere ; it absorbs moisture and carbon dioxide. CaO + H2O --> Ca(OH)2 CaO + CO2 --> CaCO3 2. It emits intense light (lime light), when heated in oxygen-hydrogen flame. 3. It combines with limited amount of water to produce slake lime. This process is called slaking of lime. Quick line slaked with sofa gives solid sodalime (CaO ). Being basic oxide. CaO + H2O --> Ca(OH)2 4. Soda lime (basic oxide) combines with some acidic oxides at high temperature. CaO + SiO2 --> CaSiO3 6CaO + S4O10 --> 2Ca3(PO4)2 CaO + CO2 --> CaCO3 Uses : i. It is an important primary material for manufacturing cement and is the cheapest form of alkali ii. It is used in the manufacture of sodium carbonate from caustic soda iii. It is employed in the purification of sugar and in the manufacture of eye stuffs Magnesium peroxide and Calcium peroxide : These are obtainned by passing H2O2 in a suspension of Mg(OH)2 AND Ca(OH)2 Uses : MgO2 is used as an antiseptic in tooth paste and as a bleaching agent.