Application of solvation excess concept to solutions of 3 : 1 and 1 : 3 electrolytes

Data on water activity in solutions of a series of 3 : 1 and 1 : 3 electrolytes AlCl₃, Al(NO₃)₃, LaCl₃, La(NO₃)₃, H₃PO₄, NaH₂PO₄] have been generalized in the frame of solvation excesses concept. Solvation excess reflects the distribution of the selected structural elements (ions or solvent particles) in the solution. The computed values have demonstrated the opposite contributions of ion association and hydration of ions and ion associates. Solvation excess concept allows determination of water molecules fraction constituting the excess at ions and their associates. The comparison of results obtained with different choice of model structural units has shown the electrolyte concentration ranges of validity of the respective models.