Properties of Hydrogen Chloride (HCl)
Hydrogen chloride (HCl) is a chemical compound composed of one hydrogen atom and one chlorine atom bonded together. It is a colorless, highly corrosive gas with a pungent odor. When dissolved in water, it forms hydrochloric acid, which is a strong acid commonly used in various industrial and laboratory processes.
The following table provides a comprehensive list of hydrogen chloride 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 | 36.461 g/mol |
| Density (0°C) | 1.5 kg/m3 |
| Dynamic Viscosity (25°C) | 14.6 µPa·s |
| Speed of Sound in Gas (0°C) | 294 m/s |
| Thermal Properties | Metric |
| Melting Point | -114.2 °C |
| Boiling Point | -85 °C |
| Thermal Conductivity (25°C) | 0.0145 W/m·K |
| Specific Heat Capacity (Cp) | 800 J/kg·K |
| Critical Constants | Metric |
| Critical Temperature (Tc) | 51.3 °C |
| Critical Pressure (Pc) | 8.26 MPa |
| Critical Density (ρc) | 450 kg/m3 |
| Electrical Properties | Metric |
| Relative Permittivity (εr) | 1.0046 |
| Optical Properties | Metric |
| Refractive Index (589 nm) | 1.000447 |
| Hazardous Data | Metric |
| NFPA Rating (Health) | 3 |
| NFPA Rating (Fire) | 0 |
| NFPA Rating (Reactivity) | 1 |
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.