Convert SO₂ gas concentration between ppmv and mg/m³ at the stated gas conditions, or estimate the theoretical SO₂ mass formed from sulfur in fuel before capture or retention.
SO₂ Formula
The ideal-gas law underlies the concentration conversion. The amount-of-substance equation below is background: its P is the SO₂ partial pressure, while the concentration converter uses total absolute sample pressure.
Variables:
- n is the amount of SO₂ (in moles, mol)
- V is the volume of the gas sample
- For this background amount equation, P is the SO₂ partial pressure; for pure SO₂ it equals total pressure. The concentration converter above instead uses total absolute sample pressure.
- R is the ideal gas constant
- T is the absolute temperature of the gas sample (K)
For the concentration converter, mg/m³ = ppmv × M_SO₂ × P_total ÷ (R × T_K), with pressure in kPa, temperature in kelvin and molar mass in g/mol. The inverse gives ppmv from mg/m³. R is 8.31446261815324 kPa·L/(mol·K), from exact SI constants; the adopted NIST nominal SO₂ molar mass is 64.064 g/mol. Concentrations must share the same wet/dry and reference basis. A gas volume fraction is limited to 0–1,000,000 ppmv; no real-gas or phase correction is made. For fuel sulfur, SO₂ formed = fuel kg × sulfur mass fraction × sulfur-to-SO₂ conversion fraction × (64.064/32.065). The nominal sulfur molar mass is 32.065 g/mol; these conventional masses are not physically exact isotope-independent constants. At 1% sulfur and 100% conversion, 1,000 kg fuel forms approximately 19.979417 kg SO₂ before controls. This does not determine released stack emissions.
What is SO₂?
SO2, or sulfur dioxide, is a colorless gas with a strong, pungent odor. It is released naturally by volcanic activity and is also a by-product of various industrial processes such as the burning of fossil fuels like coal and oil, and the smelting of mineral ores that contain sulfur. SO2 is a significant air pollutant and has harmful effects on the environment and human health. It can react with other substances in the atmosphere to form harmful compounds such as sulfuric acid, sulfurous acid and sulfate particles. These can lead to respiratory problems in humans and animals, and can also lead to acid rain which can harm vegetation and aquatic life. In addition, SO2 can react with other gases in the atmosphere to form aerosols that can reflect sunlight and contribute to climate change.
How to Calculate SO₂?
Choose the gas-concentration conversion or the fuel-sulfur mass estimate, then enter the values required for that tool:
- Choose Gas concentration for ppmv ↔ mg/m³, or Fuel sulfur for the theoretical SO₂ mass formed.
- For gas concentration, choose the conversion direction and enter the SO₂ concentration.
- Set gas temperature and total absolute pressure for the same gas-volume basis. The disclosed reference defaults are 25°C and 101.325 kPa.
- For fuel sulfur, enter fuel mass and sulfur mass percent, then set the fraction of sulfur forming SO₂. The 100% default assumes complete conversion before capture.
- Select Calculate to update the result. Unsaved edits retain the previous result; Reset clears this calculator’s saved values.
Example Problem:
Choose Gas concentration and ppmv to mg/m³ for this example at the reference conditions:
SO₂ concentration (ppmv) = 1
Total absolute sample pressure (kPa) = 101.325
Temperature (°C) = 25
Using the nominal molar mass 64.064 g/mol and R = 8.31446261815324 kPa·L/(mol·K), the converted concentration is approximately 2.618555 mg/m³.
