Dielectric Characteristics, Electrical Conductivity and Solvation of Ions in Electrolyte Solutions

Solvation and association of ions in solutions largely depend on the dielectric properties of the solvent, the distance between ions in solutions, and temperature. This paper considers the effect of temperature on static dielectric constant (DC), dipole dielectric relaxation (DR) time, and limiting (ultimate) high frequency (HF) electrical conductivity (EC) of water and some polar solvents. In the investigated temperature range (0-370 degrees C), the static DC and DR time of water decrease, and limiting HF EC passes through a maximum at 250-300 degrees C with temperature growth. The dielectric characteristics of methanol, ethanol, and propanol behave in a similar way. It is shown that the existence of an HF EC temperature maximum is due to the different nature of the temperature dependences of DC and DR time. It is suggested that the same dependences are responsible for the presence of a maximum in the temperature dependences of the dissociation degree and the ionic product of water. The influence of non-electrolytes concentration as well as metal salts on the dielectric properties of their aqueous solutions is considered. The limiting HF EC of water determines the specific EC value of aqueous electrolyte solutions. Analysis of the absorption of microwave energy by polar solvents, as well as aqueous solutions of non-electrolytes and electrolytes, at a frequency of 2455 MHz is carried out. The optimal conditions for high-frequency heating of solutions have been established. The distance between ions in aqueous solutions of inorganic salts and in non-aqueous solutions of ionic liquids is calculated. It is shown that the maximum on the concentration dependence of the specific EC can be related to ions association.

Automated summary

This study investigates the effect of temperature on the dielectric properties and electrical conductivity of water and polar solvents. It is found that the static dielectric constant and dipole dielectric relaxation time of water and alcohols decrease with temperature, while the limiting high frequency electrical conductivity reaches a maximum at 250-300 degrees Celsius. The presence of a maximum in the temperature dependences of these properties is attributed to the different nature of their temperature dependences.