Properties of Hydrogen Sulfide (H2S)
Hydrogen sulfide (H2S) is a colorless, flammable, and highly toxic gas with a distinct foul odor, often described as resembling the smell of rotten eggs. It occurs naturally in some geological formations, swamps, and the human body as a metabolic byproduct.
The following table provides a comprehensive list of hydrogen sulfide properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).
Click on the icon to switch between Metric and Imperial units.
| Physical Properties | Metric |
|---|---|
| Molar Mass | 34.082 g/mol |
| Density (0°C) | 1.539 kg/m3 |
| Dynamic Viscosity (25°C) | 12.5 µPa·s |
| Speed of Sound in Gas (0°C) | 295 m/s |
| Thermal Properties | Metric |
| Melting Point | -85.5 °C |
| Boiling Point | -59.6 °C |
| Thermal Conductivity (25°C) | 0.017 W/m·K |
| Specific Heat Capacity (Cp) | 1003 J/kg·K |
| Critical Constants | Metric |
| Critical Temperature (Tc) | 100 °C |
| Critical Pressure (Pc) | 8.94 MPa |
| Critical Density (ρc) | 310 kg/m3 |
| Electrical Properties | Metric |
| Relative Permittivity (εr) | 1.0034 |
| Optical Properties | Metric |
| Refractive Index (589 nm) | 1.00063 |
| Hazardous Data | Metric |
| Autoignition Temperature | 260 °C |
| Lower Flammability Limit | 4.3% |
| Upper Flammability Limit | 46% |
| NFPA Rating (Health) | 4 |
| NFPA Rating (Fire) | 4 |
| NFPA Rating (Reactivity) | 0 |
Unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)
Related Pages
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017. 3) Yaws, Carl L. The Yaws Handbook of Physical Properties for Hydrocarbons and Chemicals. Netherlands: Elsevier Science, 2015. 4) Fire Protection Guide to Hazardous Materials, 14th Edition. United States: National Fire Protection Association, 2010.