Diffusion coefficients for HCl and HBr in 30 wt % to 72 wt % sulfuric acid at temperatures between 220 and 300 K

Abstract

Abstract. Diffusion in sulfuric acid plays a role in heterogeneous stratospheric processes. Knowledge of diffusion coefficients is required to determine the partitioning of heterogeneous reactions between the bulk and the surface of sulfate aerosol particles. Diffusion coefficients are also needed to analyze time-dependent uptake data to obtain solubilities. In order to provide quantitatively accurate diffusion coefficients, the experimental challenges of measuring solute diffusion in strong electrolyte environments must be overcome. We use a modified diaphragm cell technique and report diffusion coefficients for HC1 and HBr in sulfuric acid solutions from 220 to 300 K. We find that the temperature and viscosity dependence of these measurements follows the equation D = cT/rl, where rl is viscosity, yielding c = 7.8 x 10-8 cm2 cP/s K for HC1 and c = 7.9 x 10-8 cm2 cP/s K for HBr. An empirical equation for predicting diffusion coefficients for other species in sulfuric acid is also presented.

Diffusion Coefficients in Cold Sulfuric Acid Solution

“…We have presented direct measurements of the liquid-phase diffusion coefficient for DMSO, DMSO 2 , 15 N-labeled DNO 3 Acknowledgment. The authors thank Bruker GmbH for the use of their NMR equipment in Karlsruhe, Germany.…”

“…3,4 In this paper, we present diffusion studies of sulfuric acid systems in the 248-298 K temperature range by the pulsed gradient spin-echo NMR technique. The systems studied include dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO 2 ), 15 Nlabeled DNO 3 , and 17 O-labeled D 2 O in solutions of 0.6-0.8 weight fraction D 2 SO 4 acid in D 2 O. Although DMSO and DMSO 2 are not directly relevant to stratospheric chemistry, this set of results helps to improve the understanding and modeling of liquid-phase diffusion in sulfate aerosol particles.…”

Assessing known pathways for HO2 loss in aqueous atmospheric aerosols: Regional and global impacts on tropospheric oxidants

“…H HO2 and H O3 are calculated as functions of temperature following recommendations of Hanson et al [1992] and Gershenzon et al [2001], respectively. The D aq for O 3 is calculated based on the expression presented by Johnson and Davis [1996], while that for O 2 − (I) is calculated following the approach of Klassen et al [1998] where is the diffusion constant at 298 K (1 × 10 −5 cm 2 s −1 ) [ Schwartz , 1984]. The temperature dependent solution viscosity, ν (T), is determined by an exponential fit to the data of Hallett [1963] for water.…”

“…H HO2 and H O3 are calculated as functions of temperature following recommendations of Hanson et al [1992] and Gershenzon et al [2001], respectively. The D aq for O 3 is calculated based on the expression presented by Johnson and Davis [1996], while that for O 2 À (I) is calculated following the approach of Klassen et al [1998]…”

Measurements of HO2 uptake to aqueous aerosol: Mass accommodation coefficients and net reactive loss

“…D l is the liquid‐phase diffusion constant (cm 2 s −1 ). We estimated this value from viscosities of concentrated aqueous electrolyte solutions [ Stokes and Mills , 1965; Isono , 1984] using the approach described by Klassen et al [1998]. This is the same value recommended by Schwartz [1984].…”