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Calcium carbonate

Calcium carbonate is an inorganic compound with the chemical formula CaCO₃, commonly known as limestone, limestone, stone powder, etc. Calcium carbonate is alkaline, basically insoluble in water but soluble in hydrochloric acid. It is one of the common substances on the earth. It exists in aragonite, calcite, chalk, limestone, marble, travertine and other rocks. It is also the main component of some animal bones or shells. Calcium carbonate is also an important building material and has a wide range of industrial uses.

Physical properties

White fine crystalline powder, tasteless and odorless. There are two forms: amorphous and crystalline. The crystal type can be divided into orthorhombic crystal system and hexagonal crystal system (anhydrous calcium carbonate is colorless orthorhombic crystal, hexahydrate calcium carbonate is colorless monoclinic crystal), which is columnar or rhombic, and its density is 2.93g/cm3 . The melting point is 1339°C (decomposed at 825-896.6°C), and the melting point is 1289°C at 10.7MPa. Hardly soluble in alcohol, soluble in ammonium chloride solution, almost insoluble in water.

Chemical nature

1. Calcium carbonate decomposes into calcium oxide and carbon dioxide at 825-896.6°C. (Industrial production of CO₂):
2. Calcium carbonate will boil and dissolve with dilute acids (such as dilute acetic acid, dilute hydrochloric acid, dilute nitric acid, etc.). The reaction also emits carbon dioxide, which is an exothermic reaction. For example: react with dilute hydrochloric acid to produce calcium chloride, water and carbon dioxide (CO₂ produced in the laboratory):
3. If the water mixed with CaCO3 is passed into excess carbon dioxide, calcium bicarbonate solution will be generated. Calcium carbonate reacts with carbonic acid solution (rainwater) to produce calcium bicarbonate. Pour CO2 into the turbid lime water, and the precipitation disappears.
4. Anhydrous calcium carbonate is heated to 1000K to transform into calcite.