Carbon dioxide

Athanor · official

CO₂ · 44.009 g/mol

Also called carbonic anhydride, dry ice, E290

Drawn from its SMILES with RDKit

WarningContains gas under pressure; may explode if heated · Contains refrigerated gas; may cause cryogenic burns or injury

Names and identifiers

IUPAC name: carbon dioxide
Synonyms: carbonic anhydride, dry ice, E290
+ 36 more
carbonic acid gas, Carbonic acid anhydride, methanedione, Carbonica, Kohlendioxyd, Carbon oxide, di-, Kohlensaure, Khladon 744, After-damp, AER Fixus, Anhydride carbonique, Dioxido de carbono, Dioxyde de carbone, Carbon oxide (CO2), R 744, Carbon-12 dioxide, INS NO.290, DTXSID4027028, INS-290, E-290, 142M471B3J, CHEBI:16526, Dioxide, Carbon, Anhydride, Carbonic, Dry ice (solid, Carbon Dioxide Air, Carbon Dioxide Nitrogen, RefChem:6625, Carbon Dioxide Compressed, Carbon Dioxide Air Mixture, Carbon Dioxide Refrigerated, CARBON DIOXIDE, USP, DTXCID507028, Air 90% Carbon Dioxide 10%, 204-696-9, Dry ice
Molecular formula: CO₂
Empirical formula: CO₂
Molecular weight: 44.009 g/mol
Exact mass: 43.98983
CAS number: 124-38-9
PubChem CID: 280
Canonical SMILES: C(=O)=O
Isomeric SMILES: C(=O)=O
InChI: InChI=1S/CO2/c2-1-3
InChIKey: CURLTUGMZLYLDI-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity

Appearance: Liquid: colorless[6]
10 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Carbon dioxide appears as a colorless odorless gas at atmospheric temperatures and pressures. Relatively nontoxic and noncombustible. Heavier than air and may asphyxiate by the displacement of air. Soluble in water. Forms carbonic acid, a mild acid. Under prolonged exposure to heat or fire the container may rupture violently and rocket. Used to freeze food, to control chemical reactions, and as a fire extinguishing agent. [1] CAMEO Chemicals
– Carbon dioxide, refrigerated liquid appears as a colorless liquid. Relatively heavier than air and can asphyxiate by the displacement of air. Under prolonged exposure to heat or fire the container may rupture violently and rocket. Used as a refrigerant and in making carbonated beverages. Used to freeze food, to control chemical reactions and as a fire extinguishing agent. [1] CAMEO Chemicals
– Carbon dioxide, solid appears as an odorless, white solid. Can cause damaging frostbite. Noncombustible and nontoxic. Liquefies at -109 °F. Can asphyxiate by displacement of air. Used as a refrigerant. [1] CAMEO Chemicals
– Liquid; Gas Vapor; Liquid; Gas Vapor; Large Crystals; CBI [2] EPA Chemical Data Reporting (CDR)
– ODOURLESS COLOURLESS COMPRESSED LIQUEFIED GAS. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Colorless, odorless gas. [4] Occupational Safety and Health Administration (OSHA)
– Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.] [5] The National Institute for Occupational Safety and Health (NIOSH)
–shown Liquid: colorless [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 233
– Solid (dry ice): white, snow-like flakes or cubes [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 239
– Colorless ... gas [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice]. [6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Odor: Odorless[6]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
–shown Odorless [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. 868
– Faintly pungent odor [6] Hazardous Substances Data Bank (HSDB)cites Pierantozzi R; Kirk-Othmer Encyclopedia of Chemical Technology. (2005). NY, NY: John Wiley & Sons; Carbon Dioxide. Online Posting Date: October 17, 2003.
Melting point: -78.5 °C (-109.3 °F, USCG 1999)[1]
5 values
3 of 3 sources agree on it (most common value).
Value As written Source
−78.5 °Cshown -109.3 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
−78 °C -109 °F (Sublimes) (NIOSH, 2024) [1] CAMEO Chemicals
−78 °C -109 °F (Sublimes) (NIOSH, 2024) [1] CAMEO Chemicals
−78 °C -109 °F (sublimes) [4] Occupational Safety and Health Administration (OSHA)
−78 °C -109 °F (Sublimes) [5] The National Institute for Occupational Safety and Health (NIOSH)
1 more value was reported but failed the checks (unreadable or out of range), so it is not shown.
Boiling point: Reported, but no value passed the checks.
The 4 values and why
Sublimes (NIOSH, 2024) (could not be read; source [1])
Sublimes (NIOSH, 2024) (could not be read; source [1])
Sublimes (NIOSH, 2024) (could not be read; source [1])
-78.464 °C @760 [mm Hg] (boiling point at or below the melting point; source [7])
Density: 1.56 at -79.0 °C (-110.2 °F) (USCG, 1999) - Denser than water[1]
4 values
3 of 4 sources agree on it (most common value).
Value As written Source
–shown 1.56 at -110.2 °F (USCG, 1999) - Denser than water [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
– 1.56 at -110.2 °F [4] Occupational Safety and Health Administration (OSHA)
– 0.72 @25 °C [7] PAC Chemical Database, U.S. Department of Energy
– 1.53(relative gas density) [5] The National Institute for Occupational Safety and Health (NIOSH)
7 more values were reported but failed the checks (unreadable or out of range), so they are not shown.
Solubility in water: Solubility in water, g/l: 2 (slightly soluble)[3]
8 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– 0.2 % at 77 °F (NIOSH, 2024) [1] CAMEO Chemicals
– 0.2 % at 77 °F (NIOSH, 2024) [1] CAMEO Chemicals
– 0.2 % at 77 °F (NIOSH, 2024) [1] CAMEO Chemicals
– In water, 2.9X10+3 mg/L at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 18
– Miscible with water (1.7 v/v at 0 °C, 0.76 v/v at 25 °C at 760 mm Hg partial pressure of CO2). [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 233
– For more Solubility (Complete) data for Carbon dioxide (6 total), please visit the HSDB record page. [6] Hazardous Substances Data Bank (HSDB)
–shown Solubility in water, g/l: 2 (slightly soluble) [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– (77 °F): 0.2% [5] The National Institute for Occupational Safety and Health (NIOSH)
log P: 0.83[3]
Vapor pressure: 4.83 × 10⁴ mmHg at 25 °C[6]
3 values
Sources disagree; from Hazardous Substances Data Bank (HSDB), the most authoritative.
Value As written Source
48300 mmHgshown 4.83X10+4 mm Hg at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
43000 mmHg Vapor pressure, kPa at 20 °C: 5720 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
750 mmHg 750 [mm Hg] @78.599999999999994 °C [7] PAC Chemical Database, U.S. Department of Energy
5 more values were reported but failed the checks (unreadable or out of range), so they are not shown.

Value	As written	Source
–	Carbon dioxide appears as a colorless odorless gas at atmospheric temperatures and pressures. Relatively nontoxic and noncombustible. Heavier than air and may asphyxiate by the displacement of air. Soluble in water. Forms carbonic acid, a mild acid. Under prolonged exposure to heat or fire the container may rupture violently and rocket. Used to freeze food, to control chemical reactions, and as a fire extinguishing agent.	[1] CAMEO Chemicals
–	Carbon dioxide, refrigerated liquid appears as a colorless liquid. Relatively heavier than air and can asphyxiate by the displacement of air. Under prolonged exposure to heat or fire the container may rupture violently and rocket. Used as a refrigerant and in making carbonated beverages. Used to freeze food, to control chemical reactions and as a fire extinguishing agent.	[1] CAMEO Chemicals
–	Carbon dioxide, solid appears as an odorless, white solid. Can cause damaging frostbite. Noncombustible and nontoxic. Liquefies at -109 °F. Can asphyxiate by displacement of air. Used as a refrigerant.	[1] CAMEO Chemicals
–	Liquid; Gas Vapor; Liquid; Gas Vapor; Large Crystals; CBI	[2] EPA Chemical Data Reporting (CDR)
–	ODOURLESS COLOURLESS COMPRESSED LIQUEFIED GAS.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Colorless, odorless gas.	[4] Occupational Safety and Health Administration (OSHA)
–	Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.]	[5] The National Institute for Occupational Safety and Health (NIOSH)
–shown	Liquid: colorless	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 233
–	Solid (dry ice): white, snow-like flakes or cubes	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 239
–	Colorless ... gas [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice].	[6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg

Value	As written	Source
–shown	Odorless	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. 868
–	Faintly pungent odor	[6] Hazardous Substances Data Bank (HSDB)cites Pierantozzi R; Kirk-Othmer Encyclopedia of Chemical Technology. (2005). NY, NY: John Wiley & Sons; Carbon Dioxide. Online Posting Date: October 17, 2003.

Value	As written	Source
−78.5 °Cshown	-109.3 °F (USCG, 1999)	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
−78 °C	-109 °F (Sublimes) (NIOSH, 2024)	[1] CAMEO Chemicals
−78 °C	-109 °F (Sublimes) (NIOSH, 2024)	[1] CAMEO Chemicals
−78 °C	-109 °F (sublimes)	[4] Occupational Safety and Health Administration (OSHA)
−78 °C	-109 °F (Sublimes)	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–shown	1.56 at -110.2 °F (USCG, 1999) - Denser than water	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–	1.56 at -110.2 °F	[4] Occupational Safety and Health Administration (OSHA)
–	0.72 @25 °C	[7] PAC Chemical Database, U.S. Department of Energy
–	1.53(relative gas density)	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	0.2 % at 77 °F (NIOSH, 2024)	[1] CAMEO Chemicals
–	0.2 % at 77 °F (NIOSH, 2024)	[1] CAMEO Chemicals
–	0.2 % at 77 °F (NIOSH, 2024)	[1] CAMEO Chemicals
–	In water, 2.9X10+3 mg/L at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 18
–	Miscible with water (1.7 v/v at 0 °C, 0.76 v/v at 25 °C at 760 mm Hg partial pressure of CO2).	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 233
–	For more Solubility (Complete) data for Carbon dioxide (6 total), please visit the HSDB record page.	[6] Hazardous Substances Data Bank (HSDB)
–shown	Solubility in water, g/l: 2 (slightly soluble)	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	(77 °F): 0.2%	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
48300 mmHgshown	4.83X10+4 mm Hg at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
43000 mmHg	Vapor pressure, kPa at 20 °C: 5720	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
750 mmHg	750 [mm Hg] @78.599999999999994 °C	[7] PAC Chemical Database, U.S. Department of Energy

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms: 3
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0
H-bond donors: 0
H-bond acceptors: 2
Rotatable bonds: 0
TPSA (Å²): 34.1
Formal charge: 0
XLogP3: 0.9 PubChem
Complexity: 18 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: D∞h of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C27.29%
O72.71%

Isotope pattern

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P: -0.58 Crippen (Wildman and Crippen 1999)
log S (water solubility): 0.25 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.41 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 44.01
log P ≤ 5 (Crippen): -0.58
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 2

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Warning

Most widely reported: 1,570 company reports to ECHA. Source [8].

Compressed gas

H280Contains gas under pressure; may explode if heated (82% of reports)
H281Contains refrigerated gas; may cause cryogenic burns or injury (20.5% of reports)

Precautionary statements: P282, P336+P317, P403, P410+P403

View all classifications (4)

[8] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 4.9% (77 of 1570) of reports.
[8] European Chemicals Agency (ECHA) · 1,570 reports · WarningH280, H281
[8] European Chemicals Agency (ECHA) · 39 reportsThis chemical does not meet GHS hazard criteria for 97.4% (38 of 39) of all reports.
[6] Hazardous Substances Data Bank (HSDB) · WarningH280

Exposure limits

PEL-TWA (8-Hour Time Weighted Average): 5000 ppm (9000 mg/m³)[4]
PEL: TWA 5000 ppm (9000 mg/m3) See Appendix G[5]
REL-STEL (Short Term Exposure Limit): 30,000 ppm (54,000 mg/m³)[4]
REL: TWA 5000 ppm (9000 mg/m3) ST 30,000 ppm (54,000 mg/m3)[5]
TLV: 5000 ppm as TWA; 30000 ppm as STEL.[3]
IDLH: 40000 ppm (NIOSH, 2024)[1]

First aid

Excerpt from NIOSH Pocket Guide for Carbon dioxide: Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible. Skin: Frostbite - If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water.[1]
Excerpt from NIOSH Pocket Guide for Carbon dioxide: Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible. Skin: Frostbite - If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water.[1]
Excerpt from NIOSH Pocket Guide for Carbon dioxide: Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible. Skin: Frostbite - If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water.[1]
General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[9]

Storage

Fireproof if in building. Cool. Ventilation along the floor.[3]
Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. Avoid heating above: 50 °C.[6]
Dry ice should not be kept in container that is not designed to withstand pressure. Containers of other substances stored over dry ice for extended periods generally absorb carbon dioxide unless they have been carefully sealed. When such containers are removed from storage and allowed to come rapidly to room temperature, the carbon dioxide may develop sufficient pressure to burst the container with explosive violence. On removal of such containers from storage, the stopper should be loosened or the container itself should be wrapped in towels and kept behind a shield.[6]
Store liquid containers in well ventilated areas. Keep cylinders away from sources of heat. Storage should not be in heavy traffic areas to prevent accidental knocking over or damage from passing or falling objects. Valve caps should remain on cylinders not connected for use. Segregate full and empty cylinders. ... Store carbon dioxide cylinders with the valve end up.[6]

Incompatibilities

Incompatible with acrylaldehyde, aziridine, metal acetylides, sodum peroxide.[6]
Dusts of various metals, such as magnesium, zirconium, titanium, aluminum, chromium & manganese are ignitable and explosive when suspended in carbon dioxide. Forms carbonic acid in water.[6]
When heated, cesium monoxide burns in ... Carbon dioxide.[6]
When potassium acetylene carbide is warmed with carbon dioxide the mass becomes incandescent.[6]

Safety data sheets on the supplier’s page: LGC Standards, RR Scientific, Sigma-Aldrich.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

[1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
[3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
[5]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
[6]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[7]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[8]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[9]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
[10]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[11]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[12]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[13]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[14]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.