ABSTRACT
This chapter describes methods of estimating air-water partition coefficients and Henry's law constants for hydrophobic chemicals, primarily. The air-water partition coefficient, also called the dimensionless Henry's law coefficient, is defined as:
(8.1)
where Cg (mollm3) is the vapor concentration of chemical and Cw (mollm3) is the aqueous solution concentration of chemical in an air/water system at equilibrium. The air-water partition coefficient may also be given in terms of mole fraction of the volatile chemical; K'Aw = y/x;. where Yi is the mole fraction of chemical vapor in air and X; is the mole fraction of chemical in water. The two partition coefficients are related; KAw = K'Aw V mJN mg• where V ml (mollm3) is the molar volume of liquid water and V mg (mol/m3) is the molar volume of air.
