Effect of Ionic Strength and Ion Pairing on Sound Absorption in Aqueous Solutions of MgSO4 and NaC1

摘要

Sound absorption in aqueous solutions of MlgSO4 is reduced by the addition NaCl. From the Eigen and Tamm multistate dissociation theory it can be shown that the absorption exhibited by MgSO4 is proportional to the ion-pair concentration. The reduction in sound absorption observed upon the addition of NaCl- is treated theoretically and is attributed to two effects; formation of NaSO4 and MgCl(+) ion-pairs and an increase in ionic strength, both of which reduce the concentration of MgSO4 ion pairs. Comparisons between theory and experiment support the theoretical treatment presented. For 0.02 molar MgSO solutions with the addition of up to 0.12 molar NaCl, the theory is in good agreement with the data of Hsu and Fisher and in substantial conflict with the data in 0.17 molar MgSO4 mixtures with NaCl of Kurtze and Tamm. For 0.1 and 0.17 molar MgSO4 solutions, the data of Kurtze and Tamm are in better agreement with theory. The extension to high ionic strength of Debye-Huckel theory derived for low ionic strength is discussed briefly. (Author)