Ethylene - Thermophysical Properties

Comprehensive thermophysical properties of Ethylene (C2H4), a highly flammable, colorless gas. This tool provides detailed chemical, physical and thermal properties at standard conditions (25°C, 1 bar) and includes critical point data, phase diagrams, and conversion between different unit systems.

Property	Value (SI)	Unit (SI)	Value (Imperial)	Unit (Imperial)
Autoignition temperature	723	K	842	°F
Boiling Point	169	K	-155	°F
Critical density	214	kg/m³	13.4	lb/ft³
Critical pressure	5.06	MPa	734	psi
Critical temperature	282.4	K	48.6	°F
Critical volume	0.00467	m³/kg	0.0748	ft³/lb
Density (gas)	1.138	kg/m³	0.07104	lb/ft³
Density (liquid) at -104°C	577	kg/m³	36.0	lb/ft³
Flammable	yes	highly	yes	highly
Flash point	137	K	-213	°F
Gas constant (R)	296.4	J/kg K	55.08	ft lbf/lb °R
Gibbs free energy of formation	68	kJ/mol	1042	Btu/lb
Heat of combustion	-1411	kJ/mol	-21626	Btu/lb
Heat of formation	52.4	kJ/mol	803	Btu/lb
Heat of evaporation at -104°C	13.6	kJ/mol	207.7	Btu/lb
Heat capacity Cp (gas)	1.53	kJ/kg K	0.365	Btu/lb°F
Heat capacity Cp (liquid)	2.40	kJ/kg K	0.574	Btu/lb°F
Heat capacity Cv (gas)	1.24	kJ/kg K	0.295	Btu/lb°F
Heat capacity Cv (liquid)	1.38	kJ/kg K	0.330	Btu/lb°F
Ionization potential	10.5	eV
log KOW (Octanol/Water Partition)	1.13
Melting point	104.15	K	-272.2	°F
Molecular Weight	28.054	g/mol	0.06185	lb/mol
Solubility in water (25°C)	0.131	mg/ml
Sound velocity	330	m/s	1082	ft/s
Specific Gravity (gas, relative to air)	0.978
Specific Heat Ratio Cp/Cv (gas)	1.24
Specific Heat Ratio Cp/Cv (liquid)	1.74
Specific Volume	0.879	m³/kg	14.1	ft³/lb
Standard molar entropy S° (gas)	219.32	J/mol K	1.87	Btu/lb °F
Standard molar entropy S° (liquid)	117.8	J/mol K	1.00	Btu/lb °F
Surface tension at -104°C	0.016	N/m
Thermal Conductivity	0.020	W/m°C	0.0118	Btu/hr ft °F
Triple point pressure	0.000122	MPa	0.0177	psi
Triple point temperature	104.0	K	-272.49	°F
Vapor (saturation) pressure	6.9449	MPa	1007.30	psi
Viscosity, dynamic	0.0103	cP	0.22	lbf s/ft² ×10⁻⁶
Viscosity, kinematic	9.05	cSt	97.4	ft²/s ×10⁻⁶