Liquid Ethylene Density Calculator

Estimate the saturated liquid density of ethylene (C2H4) at a given temperature, for cryogenic storage and petrochemical process reference.

🧊 Liquid Ethylene Density Calculator
Temperature-104°C
°C
-169°C9°C
Liquid Density
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Density (g/mL)
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Temperature (K)
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Reduced Temperature (T/Tc)
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🧊 What is Liquid Ethylene Density?

Liquid ethylene density is the mass per unit volume of ethylene (C2H4) while it exists as a saturated liquid, in equilibrium with its own vapor. Because ethylene has a very low critical temperature, just 9.2°C, it can only exist as a liquid at cryogenic or moderately cold temperatures, and its density changes substantially across that narrow liquid range, from about 652 kg/m3 near its triple point down to about 214 kg/m3 right at its critical point.

This density figure is essential for petrochemical plants that produce ethylene by steam cracking naphtha or ethane, cryogenic storage terminal operators sizing insulated tanks, pipeline engineers calculating flow rates and pump duties for liquid ethylene transport, and safety engineers estimating the volume a given mass of leaked or vented liquid ethylene would occupy.

A common point of confusion is treating ethylene like a normal room-temperature liquid. It is not, ethylene is a gas at ordinary temperatures and pressures, and only becomes liquid when cooled well below 0°C (or compressed to high pressure at a still-cold temperature). Its liquid density is also far more temperature-sensitive than water's, because ethylene's liquid range sits so close to its own critical point, where the distinction between liquid and gas disappears.

This calculator is useful because published density tables only list a handful of fixed temperature points, while real cryogenic and process engineering work often needs a density at an arbitrary in-between temperature. Using a validated correlation lets you interpolate reliably across the entire liquid range instead of guessing between table entries.

📐 Formula

ρ(T)  =  ρc ÷ Zc(1−Tr)2/7      Tr = T ÷ Tc
ρ(T) = saturated liquid density at temperature T (kg/m³)
ρc = ethylene's critical density, 214.24 kg/m³
Tc = ethylene's critical temperature, 282.35 K (9.2°C)
Zc = ethylene's critical compressibility factor, about 0.2812, derived from Tc, the critical pressure, and ρc
Tr = reduced temperature, T divided by Tc (both in Kelvin)
This is the Rackett equation, a standard chemical engineering correlation for saturated liquid density, per the Rackett equation reference. Critical property values are from the NIST Chemistry WebBook.

📖 How to Use This Calculator

Steps

1
Enter the temperature - enter the liquid ethylene temperature in degrees Celsius, between its triple point and critical point.
2
Click Calculate to see the estimated liquid density in kg/m3 and g/mL.
3
Read the chart - use the density vs temperature chart to see how density changes across the full liquid range, with your current point marked.

💡 Example Calculations

Example 1 — Normal Boiling Point

Temperature = -103.7°C (ethylene's boiling point at 1 atm).

1
T = -103.7°C = 169.45 K, Tr = 169.45 ÷ 282.35 = 0.6001
2
ρ = 214.24 ÷ 0.2812(1−0.6001)^(2/7) = 568.74 kg/m³
Result = 568.74 kg/m³ (0.5687 g/mL), matching the commonly cited density of liquid ethylene at its atmospheric boiling point.
Try this example →

Example 2 — Mid-Range Cryogenic Transport

Temperature = -50°C, a typical pressurized cryogenic transport temperature.

1
T = -50°C = 223.15 K, Tr = 223.15 ÷ 282.35 = 0.7903
2
ρ = 214.24 ÷ 0.2812(1−0.7903)^(2/7) = 482.50 kg/m³
Result = 482.50 kg/m³ (0.4825 g/mL), noticeably lower than the boiling-point density.
Try this example →

Example 3 — Near-Ambient Pressurized Storage

Temperature = 0°C, still below the 9.2°C critical point but close to it.

1
T = 0°C = 273.15 K, Tr = 273.15 ÷ 282.35 = 0.9674
2
ρ = 214.24 ÷ 0.2812(1−0.9674)^(2/7) = 345.18 kg/m³
Result = 345.18 kg/m³ (0.3452 g/mL). This is close enough to the critical point (Tr above 0.9) that the calculator flags the result as approximate.
Try this example →

❓ Frequently Asked Questions

What is the density of liquid ethylene at its boiling point?+
At its normal boiling point of about -103.7°C (169.45 K, 1 atmosphere), liquid ethylene has a density of approximately 568 to 570 kg/m3 (about 0.57 g/mL), based on both this calculator's correlation and published reference data.
How does temperature affect liquid ethylene density?+
Liquid ethylene density decreases as temperature rises, slowly at very cold temperatures and increasingly steeply as the temperature approaches the critical point at 9.2°C, where liquid and vapor densities converge to the same value, about 214 kg/m3.
What is the critical temperature of ethylene?+
Ethylene's critical temperature is about 9.2°C (282.35 K). Above this temperature, no amount of pressure can keep ethylene as a distinct liquid, it exists only as a supercritical fluid.
What formula does this calculator use for liquid ethylene density?+
This calculator uses the Rackett equation, rho(T) = rho_c divided by Z_c raised to the power of (1 minus T/T_c) raised to 2/7, where rho_c, Z_c, and T_c are ethylene's critical density, critical compressibility factor, and critical temperature. It is a widely used engineering correlation for saturated liquid density.
Is this an exact value or an estimate?+
This is an engineering estimate from a simplified correlation, not a full equation of state. It is accurate to within roughly one to two percent across most of the liquid range, but becomes less reliable within about 10°C of the critical point, where a more rigorous model like NIST REFPROP should be used instead.
Why does ethylene need to be kept so cold to stay liquid?+
Ethylene has a very low critical temperature, 9.2°C, and a low normal boiling point, -103.7°C. To store or transport it as a liquid at close to atmospheric pressure, it must be refrigerated to cryogenic temperatures, this is why liquid ethylene is typically handled in insulated cryogenic tanks and pipelines.
What is the triple point of ethylene?+
Ethylene's triple point, the temperature and pressure where solid, liquid, and vapor ethylene all coexist, is about -169.2°C (104.0 K). Below this temperature, ethylene freezes into a solid and no liquid phase can exist.
How do I convert this density from kg/m3 to g/mL?+
Divide the density in kg/m3 by 1000 to get g/mL (equivalently g/cm3). For example, 568.7 kg/m3 equals 0.5687 g/mL, this calculator shows both units automatically.
Does pressure affect this density calculation?+
This calculator assumes the ethylene is a saturated liquid, meaning it is in equilibrium with its own vapor at that temperature's corresponding vapor pressure. Compressing liquid ethylene well above its saturation pressure at a given temperature increases its density slightly above the value shown here.
What industries use liquid ethylene density data?+
Petrochemical plants that produce ethylene by steam cracking, cryogenic storage and transport operators, polyethylene and other plastics manufacturers, and process engineers designing pipelines, tanks, and pumps all rely on accurate liquid ethylene density figures for inventory calculations, equipment sizing, and safety analysis.
Tags: Liquid Ethylene Density Calculator Ethylene Density vs Temperature Cryogenic Ethylene Density Petrochemical Density Calculator Ethylene C2H4 Properties Rackett Equation Calculator Chemistry Calculator Free

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What is the density of liquid ethylene at its boiling point?

At its normal boiling point of about -103.7°C (169.45 K, 1 atmosphere), liquid ethylene has a density of approximately 568 to 570 kg/m3 (about 0.57 g/mL), based on both this calculator's correlation and published reference data.

How does temperature affect liquid ethylene density?

Liquid ethylene density decreases as temperature rises, slowly at very cold temperatures and increasingly steeply as the temperature approaches the critical point at 9.2°C, where liquid and vapor densities converge to the same value, about 214 kg/m3.

What is the critical temperature of ethylene?

Ethylene's critical temperature is about 9.2°C (282.35 K). Above this temperature, no amount of pressure can keep ethylene as a distinct liquid, it exists only as a supercritical fluid.

What formula does this calculator use for liquid ethylene density?

This calculator uses the Rackett equation, rho(T) = rho_c divided by Z_c raised to the power of (1 minus T/T_c) raised to 2/7, where rho_c, Z_c, and T_c are ethylene's critical density, critical compressibility factor, and critical temperature. It is a widely used engineering correlation for saturated liquid density.

Is this an exact value or an estimate?

This is an engineering estimate from a simplified correlation, not a full equation of state. It is accurate to within roughly one to two percent across most of the liquid range, but becomes less reliable within about 10°C of the critical point, where a more rigorous model like NIST REFPROP should be used instead.

Why does ethylene need to be kept so cold to stay liquid?

Ethylene has a very low critical temperature, 9.2°C, and a low normal boiling point, -103.7°C. To store or transport it as a liquid at close to atmospheric pressure, it must be refrigerated to cryogenic temperatures, this is why liquid ethylene is typically handled in insulated cryogenic tanks and pipelines.

What is the triple point of ethylene?

Ethylene's triple point, the temperature and pressure where solid, liquid, and vapor ethylene all coexist, is about -169.2°C (104.0 K). Below this temperature, ethylene freezes into a solid and no liquid phase can exist.

How do I convert this density from kg/m3 to g/mL?

Divide the density in kg/m3 by 1000 to get g/mL (equivalently g/cm3). For example, 568.7 kg/m3 equals 0.5687 g/mL, this calculator shows both units automatically.

Does pressure affect this density calculation?

This calculator assumes the ethylene is a saturated liquid, meaning it is in equilibrium with its own vapor at that temperature's corresponding vapor pressure. Compressing liquid ethylene well above its saturation pressure at a given temperature increases its density slightly above the value shown here.

What industries use liquid ethylene density data?

Petrochemical plants that produce ethylene by steam cracking, cryogenic storage and transport operators, polyethylene and other plastics manufacturers, and process engineers designing pipelines, tanks, and pumps all rely on accurate liquid ethylene density figures for inventory calculations, equipment sizing, and safety analysis.

📌 Quick Tips

💡Liquid ethylene only exists between its triple point, about -169.2°C (104.0 K), and its critical point, about 9.2°C (282.35 K), enter a temperature in that window.
💡Density drops steeply as temperature rises toward the critical point, where the liquid and vapor phases become identical and density falls to the critical density, about 214 kg/m3.
💡At its normal boiling point of about -103.7°C (1 atm), liquid ethylene has a density close to 568 to 570 kg/m3, this is a useful sanity-check value.
💡This calculator estimates density along the saturation curve (the liquid in equilibrium with its own vapor), not the density of a compressed liquid held well above its vapor pressure at that temperature.
💡For temperatures within about 10°C of the critical point, treat results as approximate, the underlying correlation loses accuracy very close to the critical point, use full equation-of-state software (such as NIST REFPROP) for that regime.