Properties of Hydrogen Iodide (HI)

Hydrogen iodide (HI) is a colorless gas with a pungent odor at room temperature, but it is typically handled as a solution in water. It is used in various chemical processes and reactions, including in the production of organic compounds and as a reducing agent in certain chemical reactions.

The following table provides a comprehensive list of hydrogen iodide 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.

Table of Hydrogen Iodide Properties
Physical Properties
Metric
Molar Mass127.912 g/mol
Density (0°C)4.46 kg/m3
Dynamic Viscosity (25°C)16.6 µPa·s
Speed of Sound in Gas (0°C)157 m/s
Thermal PropertiesMetric
Melting Point-50.8 °C
Boiling Point-35.6 °C
Thermal Conductivity (25°C)4.8×10-3 W/m·K
Specific Heat Capacity (Cp)228 J/kg·K
Critical ConstantsMetric
Critical Temperature (Tc)151 °C
Critical Pressure (Pc)8.31 MPa
Critical Density (ρc)976 kg/m3
Electrical PropertiesMetric
Relative Permittivity (εr)1.00234
Optical PropertiesMetric
Refractive Index (589 nm)1.000906
Hazardous DataMetric
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)

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.