Temperature dependencies of the Henry's Law constant and the aqueous phasedissociation constant of bromine chloride

Modeling ozone depletion observed in the Arctic troposphere requires mass t ransport of halogen species between the aqueous and the gas phases, which i s proportional to its Henry's Law constant (H-x). UV measurements are made in both the aqueous and gas phases to determine the solubility (H-BrCl = [B rCl(aq)]/[BrCl(g)]RT) of BrCl (279-299 K). The gas-phase absorbance spectru m (330-450 nm, 1 nm intervals) is fit for [BrCl(g)], [Br-2(g)], and [Cl-2(g )], while the absorbance value at 343 nm is used to determine (BrCl(aq)] (a nd [BrCl2-]). Dissociation (K-aq = [Br-2(aq)][Cl-2( aq)]/BrCl(aq)](2)) data are obtained from K-aq = H(Cl2)H(Br2)Kg/H-BrCl(2) where H-Cl2, H-BR2 and K -g have analogous definitions to H-BrCl and K-aq. Comparison of Henry's Law constants in Table 2 reveals that the order of solubility at 298.2 K is Br Cl > Br-2 >> Cl-2. At temperatures relevant to the Arctic, BrCl is much mor e soluble than Br-2 because of differences in Delta H degrees. Consequently , the relative flux of BrCl from the aqueous to the gas phase should not be as large as that of Br-2 Comparison of dissociation constants in Table 2 r eveals the relatively high degree of association of BrCl with H2O molecules in the aqueous phase.