SO₂ – General Information, SO₂ Gas Sensors & Relevant Applications

Properties of sulphur dioxide (SO₂)

Please note that these properties can change depending on pressure and temperature.

• Molecular weight: The molecular weight of SO₂ is about 64.07 g/mol.
• Boiling point: The boiling point of SO₂ is -10.02 degrees Celsius (14 degrees Fahrenheit) under normal pressure.
• Melting point: The melting point is -72.7 degrees Celsius (-98.9 degrees Fahrenheit) at a pressure of 1 atmosphere.
• Density: The density of SO₂ varies with pressure and temperature. At room temperature and normal pressure, the density is approximately 2.63 kg/m³.
• Physical state: SO₂ is a gas at room temperature and normal pressure.
• Solubility in water: SO₂ is very soluble in water, about 11.3 g/l at 0 degrees Celsius and about 7.8 g/l at 20 degrees Celsius.
• Odor and taste: SO₂ has a pungent, irritating odor; it is not suitable for consumption.
• Thermal conductivity: The thermal conductivity of SO₂ is about 0.0103 W/(m-K) at 25 degrees Celsius.
• Critical point: The critical point of SO₂ is at a temperature of 157.2 degrees Celsius and a pressure of 7.88 MPa.

Application examples for SO₂

• Food industry: Sulphur dioxide is used as a preservative (E220) in dried fruit, wine and other foods to prevent the growth of bacteria and mold.
• Paper and textile industry: SO₂ is used as a bleaching agent to brighten textiles and paper.
• Chemical industry: SO₂ is used as a starting material for the production of sulphuric acid (H₂SO₄), one of the most important industrial chemicals.
• Environmental technology: It is used in flue gas cleaning to remove sulphur compounds from exhaust gases and thus reduce air pollution.
• Wine production: SO₂ is used as an antioxidant and to sterilize wine barrels and bottles to protect the wine from oxidation and microbial damage.
• Refrigeration industry: Sulphur dioxide was previously used as a refrigerant before being replaced by safer alternatives.