Carbon Dioxide (CO₂) Properties & Characteristics

Calculator for carbon dioxide thermophysical properties including density, thermal data, critical parameters, and phase characteristics. Values provided for gas phase at 25°C (77°F, 298 K) and 1 atm unless otherwise specified.

CO₂ Properties Calculator

Carbon dioxide (CO₂) is a colorless, odorless gas that is relatively nontoxic and noncombustible. This calculator provides key thermophysical properties of CO₂ for various conditions.

Key Information:

Standard Conditions: 25°C (77°F, 298 K) and 1 atm
Molar Mass: 44.0095 g/mol
Specific Gravity: 1.53 (relative to air)
Critical Temperature: 304.13 K (30.98°C / 87.76°F)
Critical Pressure: 7.38 MPa (73.8 bar / 72.8 atm)

Select a property and enter conditions to calculate values.

Calculator

Inputs

Select CO₂ Property

Unit System

Results

Density-- kg/m³ or lb/ft³

Specific Heat Capacity-- kJ/kg K or Btu/lb°F

Thermal Conductivity-- W/m°C or Btu/hr ft °F

Viscosity-- cP / cSt or lbf s/ft²

Critical Parameter Value-- Varies by property

Energy Value-- kJ/kg or Btu/lb

Property	Value (SI)	Unit (SI)	Value (Imperial)	Unit (Imperial)
Molecular Weight	44.0095	g/mol	0.09702	lb/mol
Density (gas, 25°C, 1 atm)	1.795	kg/m³	0.1121	lb/ft³
Density (gas, 0°C, 1 atm)	1.977	kg/m³	0.1234	lb/ft³
Density (liquid, -37°C)	1101	kg/m³	68.73	lb/ft³
Density (solid, -78.5°C)	1562	kg/m³	97.51	lb/ft³
Specific Gravity (vs air)	1.53		1.53
Critical Density	467.6	kg/m³	29.19	lb/ft³
Critical Pressure	7.38	MPa	1070	psi
Critical Temperature	304.13	K	87.76	°F
Boiling/Sublimation Point	-78.464	°C	-109.24	°F
Triple Point Temperature	216.58	K	-69.81	°F
Triple Point Pressure	0.5180	MPa	75.12	psi
Specific Heat Capacity (Cp)	0.849	kJ/kg K	0.203	Btu/lb°F
Specific Heat Capacity (Cv)	0.658	kJ/kg K	0.157	Btu/lb°F
Specific Heat Ratio (Cp/Cv)	1.29		1.29
Thermal Conductivity	0.01663	W/m°C	0.009609	Btu/hr ft °F
Dynamic Viscosity	1.495	cP	31.22	lbf s/ft² ×10⁻⁶
Kinematic Viscosity	0.834	cSt	8.977	ft²/s ×10⁻⁶
Sound Velocity	269	m/s	883	ft/s
Heat of Vaporization (Triple Point)	353.4	kJ/kg	151.93	Btu/lb
Heat of Sublimation	591	kJ/kg	254	Btu/lb
Enthalpy of Formation	-8941	kJ/kg	-3844	Btu/lb
Gibbs Free Energy of Formation	-8953	kJ/kg	-3849	Btu/lb
Standard Molar Entropy	4.86	kJ/kg K	1.16	Btu/lb °F
Solubility in Water (20°C)	1.48	g/l	0.148	g/100g
pH of Saturated Solution	3.7		3.7
Surface Tension (melting point)	16.2	dynes/cm	16.2	dynes/cm

Important Notes

Standard Conditions: Most values are given for gas phase at 25°C (77°F, 298 K) and 1 atm pressure
Dry Ice: Solid CO₂ is commonly known as dry ice
Phase Behavior: CO₂ exhibits unique phase behavior with a triple point at 216.58 K (-56.57°C)
Toxicity: CO₂ is relatively nontoxic but can cause asphyxiation by displacement of air
Carbonic Acid: When dissolved in water, CO₂ forms mild carbonic acid (pKa1 = 6.35, pKa2 = 10.33)
Flammability: CO₂ is non-flammable

Related Properties

For temperature and pressure-dependent values, please refer to:

Density variations with temperature and pressure
Dynamic and kinematic viscosity variations
Specific heat variations
Thermal conductivity variations
Prandtl number calculations