Determination of Water and Solute Activities in H2SO4–In2(SO4)3–H2O System

The activities of water of the system H2SO4–In2(SO4)3–H2O are determined by using the isopiestic method at 298 K. The results obtained satisfactorily obey the Zdanovskii’s empirical rule. From the water activities determined isopiestically, the mean ionic activity coefficients of the solutes are calculated by applying the Mckay-Perring method. Furthermore, the applicability of the Meissner’s empirical procedure to estimation of the mean ionic activity coefficient of indium sulfate and that of the Robinson-Bower equation to evaluate the water activity to the present solution system are also discussed.