Question

Describe the fate of a quantity of benzene (C6H6) spilled into a pond and brought into contact with pond water, suspended solids and air bubbles, as well as the air above the pond.

All phases of benzene reach equilibrium at 25℃ in, with the partial pressure in air at 0.125 atm, and atmospheric pressure at 1.2 atm. If benzene has Henry’s Law constant of 0.182 M atm-1 and solid-water partition coefficient (Kd) of 2.45 L/kg, obtain its molar concentration in the water and in the air. Determine also the benzene concentration in the solid phase.

Answer 1

According to Henry's law:

The molar concentration of benzene in the water = K_H * (P_benzene in air)

= 0.182 M atm^-1 * 0.125 atm

= 0.023 M

The molar concentration of benzene in the air = 0.182 M atm^-1 * 1.2 atm = 0.218 M

The molar concentration of benzene in the solid phase = 0.182 mol/L atm^-1 * 2.45 L/kg * (1.2 - 0.125) atm = 0.479 mol/kg