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EPA On-line Tools for Site Assessment Calculation

When chemicals are released into the environment from a mixture like a petroleum hydrocarbon fuel, the water solubilities of the chemicals are typically far lower than their published solubilities. For example, the solubility of benzene is around 1750 mg/L, but typical maximum benzene concentrations resulting from equilibrium between gasoline and water are only 20 - 40 mg/L. This occurs because the concentration (or effective solubility) depends on the abundance of the chemical in the fuel.

Main idea icon Experimental, temperature-dependent version of the calculator.

Suggestion icon The effective solubility calculator only calculates the partitioning between water and a fuel. Use the mass distribution calculator to determine the partitioning (concentrations) between water, air, fuel and solids in the subsurface.

Effective Solubility Calculator  
Effective Solubility Cw = xo S

Cw = Effective solubility
xo = mole fraction (of chemical in fuel)
S = solubility

Mole Fraction xo = MFx MWo / MWx

MFx = mass fraction of selected chemical in fuel
MWo = average molecular weight of fuel
est. 105 g/mole for gasoline
est. 165 g/mole for Jet fuel
est. 230 g/mole for diesel fuel
MWX = molecular weight of selected chemical
Site Name
Solubility (S) mg/L
Optional Revised Solubility (S) mg/L
Example Fuel
Average Molecular Weight of Fuel (MWo)  
Percent Mass Fraction  
Effective Solubility (Cw) mg/L
Fuel composition note:
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