A study of the properties of cadmium chloride in water, N-methylacetamide, solutions and N-methylacetamide solutions
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1968
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Abstract
The densities and viscosities of water, N-methylacetamide (abreviated [sic] NMA), and water-NMA mixtures have been measured at 30°, 40°, and 50°C. The activational energies for viscosity of these solvents were calculated from the viscosity data. The specific conductivities of these solvents were also measured at 30°C. The densities, viscosities, activational energies, and specific conductances all exhibited a maximum when plotted as a function of the mole fraction of NMA. An attempt was made to explain these maxima. Electromotive force (EMF) measurements of cadmium chloride in water and in NMA were made over the temperature range from 30° to 90°C at 10° intervals. The standard potentials for cadmium chloride in water at these temperatures were determined with the aid of a computer. The standard potentials of cadmium chloride in NMA were determined by the extrapolation of a suitable function to zero concentration of cadmium chloride. From the EMF data, thermodynamic properties for the transfer of cadmium chloride from NMA to water were calculated. These thermodynamic properties were calculated in such a way that they represented only the effects of solute-solvent interactions. Data taken from the literature for the hydrogen chloride-water-NMA system and the cadmium chloride-water-methanol system were also treated in a similar way. Comparisons of the thermodynamic properties of these three systems were made. Finally, conductivity measurements of cadmium chloride in water, NMA, and water-NMA solutions were made at 30°C. These measurements confirmed the evidence found in the EMF studies that cadmium chloride is less dissociated in NMA than it is in water. This is unusual since the dielectric constant of NMA is greater than that of water and ordinarily a salt would be expected to be more completely ionized in the solvent with the higher dielectric constant. An explanation of this unusual behavior was made by the consideration of other factors which might outweigh the effect of dielectric constant.