Isopiestic studies of aqueous solutions at elevated temperatures VIII. The alkali-metal sulfates

Abstract Osmotic coefficients of aqueous solutions of the alkali-metal sulfates over the temperature range 383 to 498 K have been obtained from isopiestic comparisons with NaCl(aq). The ion-interaction model was fitted, by a least-squares computation, to the experimental results. A value of 1.4 for the fixed parameter α gave a better overall fit than the normally used 2.0. In this temperature range the osmotic coefficients of all four solutions decreased with increasing temperature as did activity coefficients calculated from the model. Of the four salts, Cs 2 SO 4 is the most individualistic. For Na 2 SO 4 (aq), there is acceptable agreement with previously reported results.

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