Dielectric constant and relaxation in cesium formate and cesium propionate aqueous solutions

High-frequency dielectric constant epsilon' and dielectric loss epsilon" of aqueous C2H5COOCs and HCOOCs solutions in the frequency range corresponding to the peak dipole loss of water have been studied over a wide range of concentrations. The electrical conductivity of cesium propionate solutions has been studied. The static dielectric constant epsilon(s), relaxation time tau, and relaxation-time distribution parameter alpha have been determined. The activation parameters (the Gibbs energy DeltaG(epsilon)(++), enthalpy DeltaH(epsilon)(++), and entropy DeltaS(epsilon)(++)) of dielectric relaxation have been calculated. The dielectric parameters have been found to have different trends for cesium formate and cesium propionate solutions. C2H5COOCs has been found to stabilize the hydrogen-bond network of water. From comparison of the dielectric relaxation parameters for propionate and formate solutions, it follows that the stabilizing effect is due to the hydrophobic hydration of the propionate ion.