The relative molecular weight of calcium carbonate is 100.09. It is one of the common substances on the earth. It exists in rocks such as aragonite, calcite, chalk, limestone, marble and tufa. It is also the main component of animal skeleton or shell. Calcium carbonate is also an important building material, widely used in industry.
The chemical formula of calcium carbonate is CaCO ₃, which is an inorganic compound, commonly known as limestone, limestone, stone powder, marble, etc. Calcium carbonate is tasteless and odorless, and has two forms: amorphous and crystalline.
The crystal type can be divided into orthorhombic system and hexagonal system, which are columnar or rhombic. The relative density was 2.71. It decomposes at 825 ～ 896.6 ℃ and decomposes into calcium oxide and carbon dioxide at about 825 ℃. The melting point is 1339 ℃ and 1289 ℃ at 10.7 MPa. It is insoluble in water and alcohol. It reacts with dilute acid and gives off carbon dioxide, which is exothermic. It is also soluble in ammonium chloride solution. Almost insoluble in water.
Calcium carbonate will boil and dissolve in the presence of dilute acetic acid, dilute hydrochloric acid and dilute nitric acid. When heated to 900 ℃ at 101.325 kPa, it decomposes into calcium oxide and carbon dioxide.
When heated to 900 ℃ under one atmospheric pressure, calcium carbonate will decompose into quicklime and carbon dioxide (industrial production of carbon dioxide): CaCO ₃ = △ = CaO + CO2 ↑.
Calcium carbonate will react with dilute hydrochloric acid, and it will be effervescent, forming calcium chloride, water and carbon dioxide (in the laboratory to produce carbon dioxide): CaCO ₃ + 2HCl = CaCl2 + H2O + CO2 ↑.