Studies on Solutions of High Dielectric Constant. Part VI. Activity Coefficients of some Alkyl-substituted Ammonium Halides in Aqueous and Formamide Solutions

In view of the abnormally high sotivity coefficients of tetra.akylaromonium iodides in aqueous solution. from E.H.F. measurements,reported by Devanathan and Fernando^, and contradicted by Stokes³, the work has been repeated to ascertain the correctness or otherwise of the freezing point data of Ebert, and Lange². The data now obtained are similar to those of Ebert and Lange and yield normal activity coefficient, for tetra. alkylammonium halides in aqueous solutions, The work has been attended to solutions of these salts in formamide In which normal activity coefficients, leas than 1, are obtained as in aqueous solutions,

The variation of ^\(\gamma\)\(\pm\) values with molality Indicates strong ion-solvent interaction Inspite of the large size of these tetra.alkylammonium ions. It is suggested that this interaction may be the filling up of spaces inside these 'hollow' ion. by the solvent molecules which are held inside the ion by the positive charge on the nitrogen atom.