Effect of temperature on chloride ion hydration: Hydrogen isotope effects in the dehydration of chloride ion form of Dowex 1 resins at 303 and 333K

Abstract

303 and 333K using a Rayleigh distillation type technique. The n_w (number of moles of water per equivalent resin capacity) values of 2-17 have been covered. Single stage separation factors (ɑ), free energies, enthalpies and entropies for the H/D exchange have been evaluated. Variations of ɑ with n_w for these temperatures are similar to those obtained earlier at 353K, i.e., variations being small in the n_w region of 2-6, approaching a value close to ɑ_w (separation factor for water distillation) in the nwregion of 10-11 and then level ling off at still higher nwvalues. The ɑ-values decrease with increase in temperature throughout the nwregion investigated. The results also show that at all temperatures, the H-bonds between Cl^‑ ion and neighbouring water molecules are weaker than those in bulk water. The effect of Cl^- ion on the H-bonding amongst the neighbouring water molecules decreases with increase in temperature. This is consistent with the idea that bulk water structure is destroyed more rapidly with increase in temperature than by the influence of ions on the neighbouring water molecules.