What is Calcium carbonate?
Calcium carbonate is a odourless chemical compound. It is water insoluble source of calcium. It is mainly found in rocks and is carbonic salt of calcium.
Some of the pure calcium carbonate minerals are Calcite, Vaterite, Aragonite. Biological sources of calcium carbonate are Snail shells, Egg shells, Oyster shells etc. Mostly used as an antacid or calcium supplement. PH value is about 9.91. Its common name is limestone.
Preparation of Calcium carbonate CaCO3
Calcium carbonate is primarily mined and processed from diverse natural mineral sources. It can also be made chemically by combining quicklime (calcium oxide, CaO) with water to produce calcium hydroxide (Ca(OH)2), which is then treated with carbon dioxide to form the calcium carbonate salt.
CaO + H2O → Ca(OH)2
Ca(OH)2 + CO2 → CaCO3 + H2O
It can be prepared on a large scale by passing carbon dioxide gas through calcium hydroxide (otherwise called slaked lime). However, if there is an excess passing of carbon dioxide, it results in the formation of soluble calcium hydrogen-carbonate.
Properties of Calcium carbonate CaCO3
| Sodium bicarbonate Chemical formula | CaCO3 |
| Molecular Weight/ Molar Mass | 100.0869 g/mol |
| Density | 2.71 g/cm³ |
| Boiling Point | Decomposes at 899 °C |
| Melting Point | 825 °C |
Calcium carbonate Structure CaCO3

Calcium Carbonate uses
- It is used as a dietary supplement when the quantity of calcium in the diet is less
- It is used as an antacid to relieve stomach upset, heartburn
- It is used in to purify iron from iron ore
- It is used in the refining of sugar
- It is used in agriculture to neutralize acidic soil
- It is used as scrubbing agent in household cleaning powders
- It is used in the construction of buildings and roads
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