Carbon dioxide

Carbon dioxide

Names
Other names Carbonic acid gas Carbonic anhydride Carbonic oxide Carbon oxide Carbon(IV) oxide Dry ice (solid phase)
Identifiers
CAS Number	124-38-9 Y
3D model (Jmol)	Interactive image Interactive image
3DMet	B01131
Beilstein Reference	1900390
ChEBI	CHEBI:16526 Y
ChEMBL	ChEMBL1231871 N
ChemSpider	274 Y
ECHA InfoCard	100.004.271
EC Number	204-696-9
E number	E290 (preservatives)
Gmelin Reference	989
KEGG	D00004 Y
MeSH	Carbon+dioxide
RTECS number	FF6400000
UNII	142M471B3J Y
UN number	1013 (gas), 1845 (solid)
InChI InChI=1S/CO2/c2-1-3 Y Key: CURLTUGMZLYLDI-UHFFFAOYSA-N Y InChI=1/CO2/c2-1-3 Key: CURLTUGMZLYLDI-UHFFFAOYAO
SMILES O=C=O C(=O)=O
Properties
Chemical formula	CO2
Molar mass	44.01 g·mol−1
Appearance	Colorless gas
Odor	Odorless
Density	1562 kg/m3(solid at 1 atm and −78.5 °C) 1101 kg/m3(liquid at saturation −37°C) 1.977 kg/m3(gas at 1 atm and 0 °C)
Melting point	−56.6 °C; −69.8 °F; 216.6 K (Triple point at 5.1 atm)
Sublimation conditions	−78.5 °C; −109.2 °F; 194.7 K (1 atm)
Solubility in water	1.45 g/L at 25 °C (77 °F), 100 kPa
Vapor pressure	5.73 MPa (20 °C)
Acidity (pKa)	6.35, 10.33
Magnetic susceptibility (χ)	-20.5·10−6 cm3/mol
Refractive index (nD)	1.00045
Viscosity	0.07 cP at −78.5 °C
Dipole moment	0 D
Structure
Crystal structure	trigonal
Molecular shape	linear
Thermochemistry
Specific heat capacity (C)	37.135 J/K mol
Std molar entropy (So298)	214 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−393.5 kJ·mol−1
Pharmacology
ATC code	V03AN02 (WHO)
Hazards
Safety data sheet	See: data page Sigma-Aldrich
NFPA 704	0 1 0
Lethal dose or concentration (LD, LC):
LCLo (lowest published)	90,000 ppm (human, 5 min)
US health exposure limits (NIOSH):
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
Related compounds
Other anions	Carbon disulfide Carbon diselenide Carbon ditelluride
Other cations	Silicon dioxide Germanium dioxide Tin dioxide Lead dioxide
Related carbon oxides	Carbon monoxide Carbon suboxide Dicarbon monoxide Carbon trioxide
Related compounds	Carbonic acid Carbonyl sulfide
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Carbon dioxide (chemical formula CO₂) is a colorless and odorless gas that is vital to life on Earth. This naturally occurring chemical compound is made up of a carbon atom covalently double bonded to two oxygen atoms. Carbon dioxide exists in Earth's atmosphere as a trace gas at a concentration of about 0.04 percent (400 ppm) by volume. Natural sources include volcanoes, hot springs and geysers, and it is freed from carbonate rocks by dissolution in water and acids. Because carbon dioxide is soluble in water, it occurs naturally in groundwater, rivers and lakes, in ice caps and glaciers and also in seawater. It is present in deposits of petroleum and natural gas.

Atmospheric carbon dioxide is the primary source of carbon in life on Earth and its concentration in Earth's pre-industrial atmosphere since late in the Precambrian was regulated by photosynthetic organisms and geological phenomena. As part of the carbon cycle, plants, algae, and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water, with oxygen produced as a waste product.