Hydrogen Sulfide - Thermophysical Properties

Comprehensive thermophysical properties of hydrogen sulfide (H2S), a colorless, toxic, flammable gas with applications in chemical manufacturing and metallurgy. Properties include critical parameters, density, thermal conductivity, viscosity, and phase behavior at standard conditions (25°C, 1 bara) and various temperatures.

PropertyValue 1Unit 1Value 2Unit 2Value 3Unit 3Value 4Unit 4
Autoignition temperature505K232°C450°F
Boiling Point213.6K-59.55°C-75.2°F
Critical density10.2mol/dm³348kg/m³0.675slug/ft³21.7lb/ft³
Critical pressure8.97MPa89.7bar88.5atm1301psi
Critical temperature373.3K100.2°C212.3°F
Critical volume98cm³/mol0.00288m³/kg1.48ft³/slug0.0461ft³/lb
Density (gas)44.16mol/m³1.505kg/m³0.00292slug/ft³0.0940lb/ft³
Density (liquid) at -85.5°C29116mol/m³992.3kg/m³1.925slug/ft³61.95lb/ft³
Density (liquid) at -60°C26877mol/m³916.0kg/m³1.777slug/ft³57.18lb/ft³
Flammable (gas and liquid)yes
Flash point480K207°C405°F
Gas constant, individual - R244.0J/kg·K0.06777Wh/(kg·K)1459(ft·lbf/slug·°R)45.34(ft·lbf/lb·°R)
Gibbs free energy of formation (gas)-34kJ/mol-998kJ/kg-429Btu/lb
Heat of formation (gas)-20.6kJ/mol-604kJ/kg-260Btu/lb
Heat of sublimation at -98°C25.4kJ/mol745kJ/kg320Btu/lb
Heat of evaporation at -73°C20.00kJ/mol353.4kJ/kg151.93Btu/lb
Heat capacity, Cp (gas)34.6J/mol·K1.01kJ/kg·K0.242Btu/lb·°F
Specific heat capacity, Cp (liquid) at 20 bara76.5J/mol·K2.24kJ/kg·K0.536Btu/lb·°F
Specific heat capacity, Cv (gas)26.0J/mol·K0.76kJ/kg·K0.182Btu/lb·°F
Specific heat capacity, Cv (liquid) at 20 bara37.0J/mol·K1.09kJ/kg·K0.259Btu/lb·°F
Ionization potential10.46eV
Melting point187.66K-85.5°C-121.9°F
Molecular Weight34.081g/mol0.07514lb/mol
Solubility in water at 25°C4mg/ml
Sound velocity in gas309m/s1014ft/s692mi/h
Sound velocity in liquid at 20 bara836m/s2742ft/s1873mi/h
Specific Gravity (gas) relative to air1.19
Specific Gravity (liquid) relative to water0.92
Specific Heat Ratio (gas) - Cp/Cv1.33
Specific Heat Ratio (liquid) - Cp/Cv at 20 bara2.07
Specific Volume (gas)0.023m³/mol0.66m³/kg342.44ft³/slug10.64ft³/lb
Specific Volume (liquid) at -85.5°C0.0000343m³/mol0.00101m³/kg0.519ft³/slug0.0161ft³/lb
Standard molar entropy, S° (gas)206J/mol·K6.04kJ/kg·K1.44Btu/lb·°F
Surface tension at 125°C58.1dynes/cm0.0581N/m
Thermal Conductivity0.018W/m·°C0.010400Btu/hr·ft·°F
Triple point pressure0.0233MPa0.233bar0.230atm3.38psi
Triple point temperature187.63K-85.5°C-121.94°F
Vapor saturation pressure2.0262MPa15200.0mm Hg19.9971atm293.88psi
Viscosity, dynamic (absolute)0.013cP8.6(lbm/ft·s ×10⁻⁶)0.27(lbf·s/ft² ×10⁻⁶)
Viscosity, kinematic8.505cSt91.5(ft²/s ×10⁻⁶)