Temperature dependences of the diffusion and kinetic parameters of potassium tellurite solutions in ordinary and heavy water

Abstract

On the basis of conductometric measurements, the coefficients of self-diffusion, the values of limiting ion mobility and the activation energy of the electrical conductivity of K 2TeO 3 solutions in ordinary and heavy water were determined in the temperature interval 12–45 °C. These parameters were compared with respect to the solvent nature. The values of the Stokes and the effective ionic radii as well as their hydration numbers were found. According to the terms of Samoylov's theory, K + ions in H 2O and D 2O were shown to be negatively hydrated, thus destabilizing the solvent structure in the hydration shell, while TeO 3 2− ions in both solvents were shown to be positively hydrated, having a stabilizing effect on the solvent structure in the hydration shell. The influence of the ion hydration on the solvent structure was more pronounced in D 2O, and this influence slightly increased with the increase of temperature. The changes of Gibbs free energy (Δ G λ ±o ≠), entropy (Δ S λ ±o ≠) and enthalpy (Δ H λ ±o ≠) for the transition of ions from one quasi-equilibrium state to another were calculated at different temperatures.