Definition:

Calcium carbonate (CaCO₃) is an inorganic compound, commonly known as limestone, limestone, stone powder, marble, etc.

Physical and chemical properties:

1. Physical properties: white solid, tasteless and odorless. There are two forms, amorphous and crystalline. The crystal type can be divided into orthorhombic crystal system and hexagonal crystal system, which are columnar or rhombic. The relative density is 2.71. It decomposes at 825～896.6℃ and decomposes into calcium oxide and carbon dioxide at about 825℃. The melting point is 1339°C, and the melting point is 1289°C at 10.7 MPa. Hardly soluble in water and alcohol. It reacts with dilute acid and emits carbon dioxide at the same time, showing an exothermic reaction. Also soluble in ammonium chloride solution. Almost insoluble in water.

2. Chemical properties: it will boil and dissolve in contact with dilute acetic acid, dilute hydrochloric acid and dilute nitric acid. It is decomposed into calcium oxide and carbon dioxide when heated to 900°C under 101.325 kPa.

Calcium carbonate will react with dilute hydrochloric acid and will effervescent to produce calcium chloride, water and carbon dioxide (CO₂ produced in the laboratory):

CaCO3+2HCl==CaCl₂+H₂O+CO₂↑

Excess carbon dioxide is added to water mixed with CaCO3, which will generate calcium bicarbonate solution. Calcium carbonate reacts with carbonic acid solution (rainwater) to produce calcium bicarbonate. Pour CO2 into the turbid lime water, and the precipitation disappears. The principles of these phenomena are:

CaCO3+H₂CO3==Ca（HCO3)2 or CaCO3+CO2+H2O==Ca（HCO3)2

Application areas:

1. Laboratory use

It can also be used to make carbon dioxide in the laboratory

Verification and determination of halogens in organic compound reactions. Water analysis. Verification of phosphorus. Decomposes silicate with ammonium chloride. Prepare calcium chloride solution to standardize soap. Manufacture of raw materials for optical neodymium glass and coating materials.

2. Other uses of calcium carbonate

It can be used as an additive in the food industry.

Commonly used in the construction industry and paper industry.

Within 200 mesh: It can be used for various feed additives with calcium content of more than 55.6 and no harmful ingredients.

250 mesh to 300 mesh: used as raw material for plastic factory, rubber factory, paint factory, waterproof material factory and internal and external wall painting. The whiteness is above 85 degrees.

350 mesh to 400 mesh: used to make gussets, drain pipes, and chemicals. The whiteness is above 93 degrees.

400 mesh to 600 mesh: can be used for toothpaste, soap. Whiteness above 94 degrees

800 mesh: used for rubber, plastic, cable, pvc with whiteness above 94 degrees

1250 mesh: PVC, PE, paint, coating grade products, papermaking primer, papermaking topcoat, whiteness above 95 degrees. It has high purity, high whiteness, non-toxic, odorless, low oil quality and low hardness.

Calcium carbonate can be used as a calcium supplement: the absorption rate can reach 39%, second only to calcium fruit acid, which is soluble in gastric acid, and has become the calcium supplement with the most dosage forms and most applications.