Gas/Aerosol Distribution of Formic and Acetic Acids

Data and correlations for evaluating the gas/aerosol equilibrium of formic and acetic acids are developed. The species considered include HCOOH(g), CH3COOH(g), HCOOH(aq), CH3COOH(aq), HCOO−, CH3COO−, HCOONa(s), CH3COONa(s), HCOOK(s), (HCOO)2Ca(s), and (CH3COO)2Ca(s). Based on available thermodynamic data, we show that the gas /aerosol distribution of formic and acetic acids is strongly on the gas-phase side for typical sulfate/ nitrate / ammonium / sodium / chloride / water aerosols and that dissolved formate and acetate have negligible effect on the gas/aerosol equilibrium of the other components.