carbon dioxide

carbon dioxide
	Structural formula of carbon dioxide with bond length
Ball-and-stick model of carbon dioxide	Space-filling model of carbon dioxide
Names
	IUPAC name Carbon dioxide
	Other names Carbonic acid gas; Carbonic anhydride; Carbonic dioxide; Carbonic oxide; Carbon(IV) oxide; Methanedione; R-744 (refrigerant); R744 (refrigerant alternative spelling); Dry ice (solid phase);
Identifiers
CAS Number	124-38-9 ;
3D model (JSmol)	Interactive image; Interactive image;
Beilstein Reference	1900390
ChEBI	CHEBI:16526 ;
ChEMBL	ChEMBL1231871 ;
ChemSpider	274 ;
EC Number	204-696-9;
Gmelin Reference	989
KEGG	D00004 ;
MeSH	Carbon+dioxide
PubChem CID	280;
RTECS number	FF6400000;
UNII	142M471B3J ;
UN number	1013 (gas), 1845 (solid)
	InChI InChI=1S/CO2/c2-1-3 Key: CURLTUGMZLYLDI-UHFFFAOYSA-N ; InChI=1/CO2/c2-1-3 Key: CURLTUGMZLYLDI-UHFFFAOYAO;
	SMILES O=C=O; C(=O)=O;
Properties
Chemical formula	CO2
Molar mass	44.009 g·mol−1
Appearance	Colorless gas
Odor	Low concentrations: none; High concentrations: sharp; acidic;
Density	1562 kg/m3 (solid at 1 atm (100 kPa) and −78.5 °C (−109.3 °F)); 1101 kg/m3 (liquid at saturation −37 °C (−35 °F)); 1.977 kg/m3 (gas at 1 atm (100 kPa) and 0 °C (32 °F));
Critical point (T, P)	304.128(15) K (30.978(15) °C), 7.3773(30) MPa (72.808(30) atm)
Sublimation; conditions	194.6855(30) K (−78.4645(30) °C) at 1 atm (0.101325 MPa)
Solubility in water	1.45 g/L at 25 °C (77 °F), 100 kPa (0.99 atm)
Vapor pressure	5.7292(30) MPa, 56.54(30) atm (20 °C (293.15 K))
Acidity (pKa)	Carbonic acid:; pKa1 = 3.6; pKa1(apparent) = 6.35; pKa2 = 10.33
Magnetic susceptibility (χ)	−20.5·10−6 cm3/mol
Thermal conductivity	0.01662 W·m−1·K−1 (300 K (27 °C; 80 °F))
Refractive index (nD)	1.00045
Viscosity	14.90 μPa·s at 25 °C (298 K); 70 μPa·s at −78.5 °C (194.7 K);
Dipole moment	0 D
Structure
Crystal structure	Trigonal
Point group	D∞h
Molecular shape	Linear
Thermochemistry
Heat capacity	37.135 J/(K·mol)
Std molar; entropy	214 J·mol−1·K−1
Std enthalpy of; formation	−393.5 kJ·mol−1
Pharmacology
ATC code	V03AN02 (WHO)
Hazards
NFPA 704 (fire diamond)	2 0 0 SA
	Lethal dose or concentration (LD, LC):
LCLo (lowest published)	90,000 ppm (162,000 mg/m3) (human, 5 min)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 5000 ppm (9000 mg/m3)
REL (Recommended)	TWA 5000 ppm (9000 mg/m3), ST 30,000 ppm (54,000 mg/m3)
IDLH (Immediate danger)	40,000 ppm (72,000 mg/m3)
Safety data sheet (SDS)	Sigma-Aldrich
Related compounds
Other anions	Carbon disulfide; Carbon diselenide; Carbon ditelluride;
Other cations	Silicon dioxide; Germanium dioxide; Tin dioxide; Lead dioxide; Titanium dioxide; Zirconium dioxide; Hafnium dioxide; Cerium dioxide; Thorium dioxide;
Related carbon oxides	See Oxocarbon
Related compounds	Carbonic acid; Carbonyl sulfide; Carbonyl selenide;
	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