Investigation of aqueous calcium nitrate, zinc nitrate, and zinc chloride solutions using acoustic velocity measurements

Abstract

The concentration dependence of the sound velocity at ultrasonic and hypersonic frequencies has been measured for aqueous solutions of calcium nitrate, zinc nitrate, and zinc chloride over a concentration range extending from very dilute solutions to the hydrate melt stoichiometry. Substantial velocity dispersion has been observed throughout the composition range studied for the aqueous ZnC12 system, but only at high solute concentration for the nitrate systems. Adiabatic compressibilities have been derived from the acoustic velocities and densities. A comparison of the compositional dependence of the 2-MHz adiabatic compressibilities of Ca(N0J2, Zn(NOJ2, and ZnClz solutions reveals fundamental structural differences. The magnitude of the adiabatic compressibility is shown to be a measure of the degree of complexation. Excess molar volumes and adiabatic compressibilities, derived by considering these systems to be binary mixtures of the tetrahydrate and water, are nonideal but show analogous behavior. The heat capacity ratios for several Ca(N03)2 solutions were computed from the values of the adiabatic compressibility obtained in this study and the corresponding literature values of the isothermal compressibility. IntroductionConcentrated aqueous electrolyte solutions, and particularly those having the hydrate melt stoichiometry, have in recent years assumed more interest than previously from both theoretical and technological viewpoints. The theoretical interest can largely be attributed to the ease with which a number of such systems can be supercooled over readily accessible temperature ranges; thus, these systems can be used to study the previously neglected metastable

Effects of Ionic Strength, Salt, and pH on Aggregation of Boehmite Nanocrystals: Tumbler Small-Angle Neutron and X-ray Scattering and Imaging Analysis

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Looking at the “Water-in-Deep-Eutectic-Solvent” System: A Dilution Range for High Performance Eutectics

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Further Extending the Dilution Range of the “Solvent-in-DES” Regime upon the Replacement of Water by an Organic Solvent with Hydrogen Bond Capabilities

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