Properties of Sulfur Dioxide (SO2)

Sulfur dioxide (SO2) is a colorless, toxic gas with a pungent odor. It is produced primarily by the burning of fossil fuels containing sulfur, such as coal and oil, and is a significant air pollutant.

The following table provides a comprehensive list of sulfur dioxide 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 Sulfur Dioxide Properties
Physical Properties
Metric
Molar Mass64.065 g/mol
Density (0°C)2.858 kg/m3
Dynamic Viscosity (25°C)12.9 µPa·s
Speed of Sound in Gas (0°C)209 m/s
Thermal PropertiesMetric
Melting Point-75.5 °C
Boiling Point-10 °C
Thermal Conductivity (25°C)8.5×10-3 W/m·K
Specific Heat Capacity (Cp)622 J/kg·K
Critical ConstantsMetric
Critical Temperature (Tc)157.7 °C
Critical Pressure (Pc)7.88 MPa
Critical Density (ρc)524 kg/m3
Electrical PropertiesMetric
Relative Permittivity (εr)1.00075
Optical PropertiesMetric
Refractive Index (589 nm)1.000686
Hazardous DataMetric
NFPA Rating (Health)3
NFPA Rating (Fire)0
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)

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.