SOLUBILITIES OF PYRUVIC-ACID AND THE LOWER (C-1-C-6) CARBOXYLIC-ACIDS- EXPERIMENTAL-DETERMINATION OF EQUILIBRIUM VAPOR-PRESSURES ABOVE PURE AQUEOUS AND SALT-SOLUTIONS

Henry's law constants KH' (mol kg(-1) atm(-1)) have been determined at 298.15 K for the following organic acids: formic acid (5.53 +/- 0.27 x 10(3)); acetic acid (5.50 +/- 0.29 x 10(3)); propionic acid (5.71 +/ - 0.34 x 10(3)); n-butyric acid (4.73 +/- 0.18 x 10(3)); isobutyric ac id (1.13 +/- 0.12 x 10(3)); isovaleric acid (1.20 +/- 0.11 x 10(3)) an d neovaleric acid (0.353 +/- 0.04 x 10(3)). They have also been determ ined from T = 278.15 K to T = 308.15 K for n-valeric acid (In (KH') = -14.3371 + 6582.96/T); n-caproic acid (In (KH') = -13.9424 + 6303.73/T ) and pyruvic acid (In (KH') = -4.41706 + 5087.92/T). The influence of 9 salts on the solubility of pyruvic acid at 298.15 K has been measur ed. Pyruvic acid is soluble enough to partition strongly into aqueous atmospheric aerosols. Other acids require around 1 g of liquid water m (-3) (typical of clouds) to partition significantly into the aqueous p hase. The degree of partitioning is sensitive to temperature. Consider ing solubility and dissociation (to formate) alone, the ratio of formi c acid to acetic acid in liquid water in the atmosphere (at equilibriu m with the gas phase acids) is expected to increase with rising pH, bu t show little variation with temperature.