Acetylene - Thermophysical Properties

Chemical, Physical and Thermal Properties of Acetylene (Ethyne - C2H2). A colorless gas widely used as a fuel and chemical building block with various thermophysical properties at 25°C (77°F, 298 K) and atmospheric pressure.

PropertyValueUnit
Molecular Weight26.04
Specific Gravity0.90
Specific Volume14.9 / 0.93ft³/lb / m³/kg
Density of liquid at atmospheric pressure43.0 / 693lb/ft³ / kg/m³
Absolute Viscosity6.72×10⁻⁶ / 0.01lbm/ft·s / centipoises
Sound velocity in gas343m/s
Specific Heat (cp)0.40 / 1674Btu/lb·°F / J/kg·K
Specific Heat Ratio (cp/cv)1.25
Gas constant (R)59.3 / 319ft·lb/lb·°R / J/kg·°C
Thermal Conductivity0.014 / 0.024Btu/hr·ft·°F / W/m·°C
Boiling Point (saturation at 14.7 psia)-103 / -75°F / °C
Latent Heat of Evaporation at boiling point264 / 614000Btu/lb / J/kg
Freezing or Melting Point at 1 atm-116 / -82.2°F / °C
Latent Heat of Fusion23 / 53500Btu/lb / J/kg
Critical Temperature97.1 / 36.2°F / °C
Critical Pressure907 / 6.25psia / MN/m²
FlammableYes
Heat of combustion1450 / 21600 / 50200Btu/ft³ / Btu/lb / kJ/kg