Ethylene Ethene C2H4 Properties

Reference data and engineering information about ethylene ethene c2h4 properties for miscellaneous applications.

ethyleneetheneC2H4propertiesData Table

Overview

Engineering reference data for Ethylene Ethene C2H4 Properties in miscellaneous.

Key Formulas

Unit Conversion

$y = x \cdot k$

Multiply by conversion factor.

Linear Interpolation

$y = y_1 + \frac{(x - x_1)(y_2 - y_1)}{x_2 - x_1}$

Estimate between two known points.

Percentage

$p = \frac{\text{part}}{\text{whole}} \times 100\%$

Part as fraction of whole.

Variables

Symbol	Description	Unit
$x$	Input value	—
$y$	Output value	—
$k$	Conversion factor	—

Thermophysical Properties Data

The following table contains key thermophysical and chemical properties of ethylene gas at 25 °C (298 K) and 1 bara unless otherwise specified.

38 rows

Thermophysical and chemical properties of ethylene (C₂H₄). Values are for gas phase at 25 °C and 1 bara unless noted otherwise.
Property	Value (SI)	Unit	Value (Imperial)	Unit
Autoignition temperature	723	K	450	°C
Boiling Point	169	K	-104	°C
Critical density	7.63	mol/dm³	214	kg/m³
Critical pressure	5.06	MPa	50.6	bar
Critical temperature	282.4	K	9.2	°C
Critical volume	131	cm³/mol	0.00467	m³/kg
Density (gas)	40.6	mol/m³	1.138	kg/m³
Density (liquid, -104°C)	20567	mol/m³	577	kg/m³
Flammable (gas & liquid)	yes, highly
Flash point	137	K	-136	°C
Gas constant (individual, R)	296.4	J/(kg·K)	0.0823	Wh/(kg·K)
Gibbs free energy of formation (gas)	68	kJ/mol	1042	Btu/lb
Heat of combustion (gas)	-1411	kJ/mol	-21626	Btu/lb
Heat of formation (gas)	52.4	kJ/mol	803	Btu/lb
Heat of evaporation (-104°C)	13.6	kJ/mol	207.7	Btu/lb
Heat capacity, Cp (gas)	42.9	J/(mol·K)	1.53	kJ/(kg·K)
Heat capacity, Cp (liquid, -104°C)	67.4	J/(mol·K)	2.40	kJ/(kg·K)
Heat capacity, Cv (gas)	34.6	J/(mol·K)	1.24	kJ/(kg·K)
Heat capacity, Cv (liquid, -104°C)	38.7	J/(mol·K)	1.38	kJ/(kg·K)
Ionization potential	10.5	eV
log KOW	1.13
Melting point	104.15	K	-169.0	°C
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)	0.978	(relative to air)
Specific Heat Ratio (gas), Cp/Cv	1.24
Specific Heat Ratio (liquid), Cp/Cv	1.74
Specific Volume	0.0247	m³/mol	0.879	m³/kg
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 (-104°C)	16.00	dynes/cm	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	-169.16	°C
Vapor (saturation) pressure	6.9449	MPa	1007.30	psi
Viscosity, dynamic (absolute)	0.0103	cP
Viscosity, kinematic	9.05	cSt

Source: engineeringtoolbox.com

Phase Behavior and Critical Points

Ethylene is a gas under standard conditions. Its phase state changes with pressure and temperature, as shown on its phase diagram.

Critical Point: This is the point on the phase diagram where the distinction between the liquid and gas phases disappears. For ethylene, this occurs at 282.4 K (9.2 °C) and 5.06 MPa. At or above this temperature and pressure, ethylene exists as a supercritical fluid.
Triple Point: This is the unique temperature and pressure where the solid, liquid, and gas phases coexist in equilibrium. For ethylene, the triple point is at 104.0 K (-169.16 °C) and 0.000122 MPa.
Saturation Curve: The curve between the triple point and the critical point represents the ethylene boiling point as a function of pressure (or equivalently, the saturation pressure as a function of temperature).

Detailed data for ethylene's properties as a function of temperature and pressure can be found for:

Density and specific weight
Dynamic and kinematic viscosity
Specific heat (Cp and Cv)
Thermal conductivity

Key Thermodynamic Relationships

The Specific Heat Ratio ( $\gamma$ or $k$ ) is a fundamental property for process engineering, especially for compressible flow and compression calculations. $\gamma = \frac{C_p}{C_v}$ For ethylene gas, $\gamma = 1.24$ .

The individual gas constant ( $R_{spec}$ ) can be calculated from the universal gas constant ( $R = 8.314 \, \text{J/(mol·K)}$ ) and the molar mass ( $M = 28.054 \, \text{g/mol}$ ): $R_{spec} = \frac{R}{M}$ This yields the value of $296.4 \, \text{J/(kg·K)}$ listed in the properties table.

References

Original Source

Source: engineeringtoolbox.com