Calcium carbonate

Calcium carbonate
	; Calcium, Ca Carbon, C Oxygen, O
Names
	IUPAC name Calcium carbonate
	Other names Aragonite; Calcite; Chalk; Lime; Limestone; Marble; Oystershell; Pearl;
Identifiers
CAS Number	471-34-1 ;
3D model (JSmol)	Interactive image; Interactive image;
ChEBI	CHEBI:3311 ;
ChEMBL	ChEMBL1200539 ;
ChemSpider	9708 ;
DrugBank	DB06724;
ECHA InfoCard	100.006.765
EC Number	207-439-9;
E number	E170 (colours)
KEGG	D00932 ;
PubChem CID	10112;
RTECS number	FF9335000;
UNII	H0G9379FGK ;
CompTox Dashboard (EPA)	DTXSID3036238 ;
	InChI InChI=1S/CH2O3.Ca/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2 Key: VTYYLEPIZMXCLO-UHFFFAOYSA-L ; InChI=1/CH2O3.Ca/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2 Key: VTYYLEPIZMXCLO-NUQVWONBAS;
	SMILES [Ca+2].[O-]C([O-])=O; C(=O)([O-])[O-].[Ca+2];
Properties
Chemical formula	CaCO3
Molar mass	100.0869 g/mol
Appearance	Fine white powder or colorless crystals; chalky taste
Odor	odorless
Density	2.711 g/cm3 (calcite); 2.83 g/cm3 (aragonite)
Melting point	1,339 °C (2,442 °F; 1,612 K) (calcite) ; 825 °C (1,517 °F; 1,098 K) (aragonite)
Boiling point	decomposes
Solubility in water	0.013 g/L (25 °C)
Solubility product (Ksp)	3.3×10−9
Solubility in dilute acids	soluble
Acidity (pKa)	9.0
Magnetic susceptibility (χ)	−3.82×10−5 cm3/mol
Refractive index (nD)	1.59
Structure
Crystal structure	Trigonal
Space group	32/m
Thermochemistry
Std molar; entropy (S⦵298)	93 J/(mol·K)
Std enthalpy of; formation (ΔfH⦵298)	−1207 kJ/mol
Pharmacology
ATC code	A02AC01 (WHO) A12AA04 (WHO)
Hazards
NFPA 704 (fire diamond)	0 0 0
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	6450 mg/kg (oral, rat)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp)
Safety data sheet (SDS)	ICSC 1193
Related compounds
Other anions	Calcium bicarbonate
Other cations	Beryllium carbonate; Magnesium carbonate; Strontium carbonate; Barium carbonate; Radium carbonate; Zinc carbonate; Cadmium carbonate; Lead(II) 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). verify (what is ?) Infobox references

Calcium carbonate is a chemical compound with the chemical formula Ca CO₃. It is a common substance found in rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls. Materials containing much calcium carbonate or resembling it are described as calcareous. Calcium carbonate is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues.

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