Studying the Structure of Water in Aqueous KI Solutions Using Viscometry, Densitometry, Conductometry, and IR Spectroscopy

Dynamic viscosity and density of aqueous KI solutions are measured in a temperature range of 283.15-333.15 K for molar fractions from 0 to 0.07. Specific electrical conductivity of these solutions is measured for molar concentrations from 0.001 mol/L to 0.01 mol/L. The absorption spectra of these solutions in the IR region are derived for molar fractions from 0 to 0.082; the frequency of OH stretchings of the water molecules is determined. Activation parameters of the viscous flow of aqueous KI solutions, partial molar volume of KI in solution, volumetric thermal expansion coefficient of the solution, energy and length of hydrogen bonds between water molecules in the solution, effective radii of K+ and I- ions in water, hydration numbers, and activation parameters of ionic conductivity at the considered temperatures and concentrations are calculated from the experimental data. It is established that the enthalpy of viscous flow activation, entropy of viscous flow activation, and hydrogen bond energy decrease with increasing solution concentration, while the partial KI molar volume, solution's volumetric thermal expansion coefficient, and hydrogen bond lengths increase. It is also shown that effective radii of K+ and I- ions in water and hydration numbers are r(eff)(K+) = 3.18 angstrom, r(eff)(I-) = 3.13 angstrom, N-Gamma(K+) = 11.4, N-Gamma(I-) = 7.6, respectively, while the Gibbs activation energy, enthalpy, and entropy of ionic conduction decrease with increasing temperature.