Structure formation features of water and concentrated aqueous lithium halide solutions at low temperatures from the data of integral equation method

The structure of water and the influence of halide ions on the structure formation of concentrated LiX : H₂O (1 : 5; X = Cl, Br, I) solutions at low temperatures were studied by the method of integral equations. Based on the results obtained, supercooling of pure water is expected to significantly enhance the tetrahedral ordering of its molecules, strengthen hydrogen bonding in the system, and decrease the number of the nearest-neighbor water molecules. The effects for the solutions on lowering the temperature include a partial restoration of the tetrahedral network of H-bonds of the solvent molecules, insignificant increase in the number of the nearest-neighbor water molecules, enhancement of the coordination ability of Li⁺ cation, strengthening of hydrogen bonding between anions and water molecules in the first hydration shell, increase in the number of solvent-separated ion pairs, and weakening of the temperature effect on these structural parameters in the following order of solutions: LiCl > LiBr > LiI. The probability of contact ion pair formation in the systems studied should appreciably decrease. The temperature should to a greater extent influence the associative ability of larger anions.