Molar volumes of multicharged electrolytes in water and aqueous sulphuric acid

The apparent molar volumes, φ_v, of aluminium ammonium sulphate and potassium aluminium sulphate in water and aqueous sulphuric acid (0.01, 0.05, 0.10 and 0.15 N) at different concentrations and temperatures have been estimated from the densities of the solutions measured by hydrostatic balance. The φ_v values vary linearly with square root of concentrations. The limiting apparent molar volume, φ⁰_v, and the experimental slope S_v, have been interpreted in terms of solute-solvent and solute-solute interactions, respectively. The φ⁰_v values vary with temperature and can be represented in the power series of temperature. Structure making/breaking capacity of the electrolyte is inferred from the sign of ?φ⁰_v/?T²] values. Both the electrolytes behave as structure breakers in water but structure makers in aqueous sulphuric acid. The molar expansibility, at infinite dilution have been found to be the same for both electrolytes at 290.5 K.