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

被引:28
作者
Bartlett, WP [1 ]
Margerum, DW [1 ]
机构
[1] Purdue Univ, Dept Chem, W Lafayette, IN 47907 USA
关键词
D O I
10.1021/es990300k
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
Modeling ozone depletion observed in the Arctic troposphere requires mass transport of halogen species between the aqueous and the gas phases, which is 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 = [BrCl(aq)]/[BrCl(g)]RT) of BrCl (279-299 K). The gas-phase absorbance spectrum (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)] (and [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 BrCl > Br-2 >> Cl-2. At temperatures relevant to the Arctic, BrCl is much more 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 reveals the relatively high degree of association of BrCl with H2O molecules in the aqueous phase.
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页码:3410 / 3414
页数:5
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