Calcium oxide also commonly known as quick lime is one of the most important compounds of calcium. Here, we will study about the preparation, physical and chemical properties and uses of calcium oxide CaO, Quick lime.
Preparation of Calcium oxide (CaO), Quick lime
Calcium oxide has Chemical formula CaO. Common name of calcium oxide (CaO) is quick lime. The preparation of Calcium oxide ( CaO ) can be done as follows :
By Heating Limestone (CaCO3) to form Calcium oxide (CaO)
CaO can be prepared by heating CaCO3 in a rotatory kiln at 1070-1270K.
CaCO3 + heat ………………………….> CaO + CO2 +179.9 KJ
CO2 should be removed as soon as possible to keep the reaction going on in a forward direction. If the temperature rises above 1270K , SiO2 reacts with CaO above 1270K to form CaSiO3 ( Calcium silicate )
Properties of Calcium oxide CaO, ( Quick lime )
- Quick lime absorbs moisture and CO2 to form slaked lime and calcium carbonate.
CaO + H2O ……………….> Ca(OH)2 slaked lime
CaO + CO2 ………………….> CaCO3 Calcium carbonate
2. CaO ( Quick lime ) slaked with NaOH ( caustic soda ) gives a solid called soda lime (CaO + NaOH)
Reaction of Quick lime ( CaO ) and Water
Quick lime ( hard lumps) reacts with water to form slaked lime. Therefore, a large amount of heat energy is released. This process is called slaking of lime. The heat energy converts water in to steam. The amount of energy released is -64.5 KJ/mol
Calcium oxide CaO, colour
Calcium oxide is a white amorphous solid having melting point 2870 K
Reaction of Calcium oxide CaO, quick lime with acids and acid oxides
Calcium oxide is a basic oxide reacts with acids as follows:
1. Calcium oxide reacts with HCl to form calcium hydrochloride.
CaO (Basic oxide) + 2HCl …………….> CaCl2 + H2O
2. Quick lime ( CaO ) reacts with SiO2 and SO2 to form calcium silicate and calcium sulphite.
CaO + SiO2 + heat ………………………> CaSiO3 ( Calcium silicate )
CaO + SO2 ………………….> CaSO3 ( Calcium sulphite )
3. Calcium oxide reacts with P4O10 to form calcium phosphate
6CaO + P4O10 +heat …………………..> 2 Ca3(PO4)2
4. Quick lime reacts with coke at 2273K to form CaC2 and CO
CaO + 3C ……………………….> CaC2 + CO
5. Calcium oxide reacts with ammonium salts releases NH3 gas
CaO + NH4Cl …………………..> CaCl2 + 2 NH3 + H2O
Uses of Calcium oxide CaO, Quick lime
- Calcium oxide is used as a flux in metallurgy.
- Quick lime is used for the preparation of cement, glass, Na2CO3 and CaC2
- CaO is used in the purification of sugar.
- Quick lime is used in drying alcohols and non acidic gases.
- It is used in the preparation of building materials.
FAQ’s related to Calcium oxide,CaO
- What is the calcium oxide chemical formula ?
Answer : Calcium oxide chemical formula is CaO
2. What is the common name of calcium oxide ?
Answer : Common name of CaO is quick lime.
3. What is formed by the reaction of CaO with H2O ?
Answer : Calcium oxide reacts with water to form calcium hydroxide
4. Is calcium oxide acid or base ?
Answer : Calcium oxide is the basic oxide because it reacts with H2O to form calcium hydroxide Ca(OH)2
Check out the structure of NH3 here
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