142. Solving a chemistry problem

Surfactant dissolved in water is adsorbed on the surface of mercury - water according to the Langmuir equation. At a surfactant concentration of 0.3 mol / L, the degree of surface filling is 0.6. Calculate the surface tension at the mercury – solution interface at 298 K if the surfactant concentration is 0.2 mol / L. The limiting value of the area occupied by the surfactant molecule on the surface is assumed to be 0.20 nm2 and the surface tension at the mercury-water interface is 0.373 J / m2.