Jpd. Abbatt, INTERACTIONS OF HBR, HCL, AND HOBR WITH SUPERCOOLED SULFURIC-ACID-SOLUTIONS OF STRATOSPHERIC COMPOSITION, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 100(D7), 1995, pp. 14009-14017
The time-dependent uptakes of HBr and HCl by supercooled solutions of
sulfuric acid have been studied using a low-temperature flow tube coup
led to a mass spectrometer. From these experiments, typical values for
the quantity KD-1/2 (where H* is the effective Henry's law constant
and D is the liquid phase diffusion coefficient) have been measured to
be 1100 and 3.3 (M/atm)(cm(2)/s)(1/2) for HBr and HCl, respectively,
on 59.6 wt% sulfuric acid at 210 K. By estimating values for the liqui
d phase diffusion coefficient, these measurements indicate that HBr is
over 2 orders of magnitude more soluble in atmospheric sulfate aeroso
ls than HCl. Similarly, HD1/2 for HOBr on 69.8 wt% sulfuric acid at 22
8 K has been measured to be 20 (M/atm)(cm(2)/s)(1/2), implying that HO
Br, too, is highly soluble in sulfuric acid solutions. By exposing sul
furic acid films simultaneously to HOBr and either HCl or HBr, the liq
uid phase reactions HOBr + HCl --> BrCl + H2O and HOBr + HBr --> Br-2
+ H2O have been studied. The results indicate that the HOBr/HCl hetero
geneous reaction may play an important role in the activation of strat
ospheric chlorine under volcanic aerosol conditions.