with:
*σ is surface tension of the mixture
*σ is surface tension of pure water 
*a is component specific constant (see table below)
*x is mole fraction of the solvated component
The equation can be rearranged to be explicit in a:
This allows the direct calculation of that component specific parameter a from experimental data.
The equation can also be written as:
with:
*γ is surface tension of the mixture
*γ is surface tension of pure water
*R is ideal gas constant 8.31 J/(mol*K)
*T is temperature in K
*ω is cross-sectional area of the surfactant molecules at the surface
The surface tension of pure water is dependent on temperature. At room temperature (298 K), it is equal to 71.97 mN/m