Features of ion hydration and ion association in sub- and supercritical aqueous solutions of rubidium bromide

Results of investigations by the integral equation method in the XRISM approximation of features of structure formation in sub- and supercritical 0.5 M aqueous solution of RbBr. As the system passes from the sub- to supercritical state, the tetrahedral network of the solvent is destroyed, which is typical of water and aqueous solutions; thermal dehydration of the cation and anion are also observed. Dehydration is accompanied by contraction of the first hydration sphere of Rb⁺ and extension of the first hydration sphere of Br⁻. Both in sub- and supercritical solutions conditions a minor amount of contact ion pairs is present whose fraction is Higher by 15% compared to that in standard conditions.