Calcium carbonate

Calcium carbonate
Calcium carbonate.png
Calcium-carbonate-xtal-3D-SF.png
Calcium carbonate.jpg
Names
IUPAC name
Calcium carbonate
Other names
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard100.006.765
EC Number207-439-9
E numberE170 (colours)
KEGG
RTECS numberFF9335000
UNII
Properties
CaCO3
Molar mass100.0869 g/mol
AppearanceFine white powder; chalky taste
Odorodorless
Density2.711 g/cm3 (calcite)
2.83 g/cm3 (aragonite)
Melting point1,339 °C (2,442 °F; 1,612 K) (calcite)
825 °C (1517 °F; 1,098 K) (aragonite) [1]
Boiling pointdecomposes
0.013 g/L (25 °C)[2][3]
3.3×109[4]
Solubility in dilute acidssoluble
Acidity (pKa)9.0
-38.2·10−6 cm3/mol
1.59
Structure
Trigonal
32/m
Thermochemistry
93 J·mol−1·K−1[5]
−1207 kJ·mol−1[5]
Pharmacology
WHO) WHO)
Hazards
Safety data sheetICSC 1193
NFPA 704
Lethal dose or concentration (LD, LC):
6450 mg/kg (oral, rat)
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp)[6]
Related compounds
Other anions
Calcium bicarbonate
Other cations
Magnesium carbonate
Strontium carbonate
Barium carbonate
Related compounds
Calcium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Crystal structure of calcite

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which is a type of sedimentary rock build mainly of calcite) and is the main component of pearls and the shells of marine organisms, snails, and eggs. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It is medicinally used as a calcium supplement or as an antacid, but excessive consumption can be hazardous.

Chemistry

Calcium carbonate shares the typical properties of other carbonates. Notably,

CaCO3(s) + 2H+(aq) → Ca2+(aq) + CO2(g) + H2O (l)
CaCO3 (s) → CaO (s) + CO2 (g)

Calcium carbonate will react with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate.

CaCO3 + CO2 + H2O → Ca(HCO3)2

This reaction is important in the erosion of carbonate rock, forming caverns, and leads to hard water in many regions.

An unusual form of calcium carbonate is the hexahydrate, ikaite, CaCO3·6H2O. Ikaite is stable only below 6 °C.

Other Languages
Afrikaans: Kalsiumkarbonaat
bosanski: Kalcij-karbonat
Esperanto: Kalcia karbonato
한국어: 탄산 칼슘
Bahasa Indonesia: Kalsium karbonat
македонски: Калциум карбонат
Bahasa Melayu: Kalsium karbonat
Nederlands: Calciumcarbonaat
norsk nynorsk: Kalsiumkarbonat
oʻzbekcha/ўзбекча: Kalsiy karbonat
Simple English: Calcium carbonate
slovenščina: Kalcijev karbonat
српски / srpski: Калцијум-карбонат
srpskohrvatski / српскохрватски: Kalcijum karbonat
українська: Карбонат кальцію
Tiếng Việt: Canxi cacbonat
吴语: 碳酸钙
粵語: 碳酸鈣
中文: 碳酸鈣