| Abstract
| - The solubility of gas-phase ethanol (ethyl alcohol, CH3CH2OH, EtOH) in aqueous sulfuric acid solutionswas measured in a Knudsen cell reactor over ranges of temperature (209−237 K) and acid composition(39−76 wt % H2SO4). Ethanol is very soluble under these conditions: effective Henry's law coefficients,H*, range from 4 × 104 M atm-1 in the 227 K, 39 wt % acid to greater than 107 M atm-1 in the 76 wt % acid.In 76 wt % sulfuric acid, ethanol solubility exceeds that which can be precisely determined using the Knudsencell technique but falls in the range of 107−1010 M atm-1. The equilibrium concentration of ethanol in uppertropospheric/lower stratospheric (UT/LS) sulfate particles is calculated from these measurements and comparedto other small oxygenated organic compounds. Even if ethanol is a minor component in the gas phase, it maybe a major constituent of the organic fraction in the particle phase. No evidence for the formation of ethylhydrogen sulfate was found under our experimental conditions. While the protonation of ethanol does augmentsolubility at higher acidity, the primary reason H* increases with acidity is an increase in the solubility ofmolecular (i.e., neutral) ethanol.
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