STUDIES OF ACTIVITY COEFFICIENTS OF NONELECTROLYTES IN AQUEOUS SALT SOLUTIONS X. THE SOLUBILITIES OF p-NITROBENZOIC ACID IN AQUEOUS SALT SOLUTIONS.

The solubilities of p-nitrobenzoic acid in aqueous solutions of NaCl, KCl, NaBr, KBr, NaClO_4, SrCl_2 and BaCl_2 were determined at 25°. Following Randall and Failey, some assumptions about the activity coefficients of the ions of ia-nitrobenzoio acid in salt solutions were made and thereby it was possible to calculate the activity coefficients f_u's of its undissociated molecules in these salt solutions, The plots of Iogf_u vs. the salt concentrations C__s are approximately straight lines, from whose slopes the values of salting-out constants k's were obtained. All k's are positive, except that of NaClO_4, and the salting-out order of the undissociated part of p-nitrobenzoic acid is: SrCl_2BaCl_2NaClNaBrKClKBrNaClO_4 We also determined the solubilities of o-nitrobenzoic acid in aqueous solutions of LiCl, SrCl_2 and BaCl_2 at 25°, and calculated the salting-out constants of the undissociated part of the acid in these salt solutions as supplementary data to those of Article V of this series. Finally, we compared the values of the salting-out constants of o-, m- and p-nitrobenzoic acid molecules in the same salt solutions of nine kinds. At 25° supplementary notes: (A) additional data of the solubilities of o-nitrobenzoic acid in three-salt solutions, (B) comparison of the salting-out of the three isomeric nitrobenzoic acids.