X-ray Diffraction Studies on Supercooled Aqueous Lithium Bromide and Lithium Iodide Solutions

Abstract

X-ray diffraction measurements were performed on liquid LiBr • 5H 2 0 and Lil • 5H 2 0 at temperatures from -30 to 25 °C. The total radial distribution functions did show that on supercooling the hydration shell of the halide ions becomes more structured, while that of the lithium ions becomes distorted. The larger the halide ion, the stronger becomes the water-water interaction around halide ions with lowering temperature. However, the distance between the water molecules in the hydration shells of the halide ions depends little on their size. On the basis of the present results, together with those of our previous investigation on LiCl • 5H 2 0 at temperatures from -135 to 100°C, the effects of temperature and the size of the halide ions on the structure of the solution are discussed.

X-ray Diffraction Study on Aqueous Scandium(III) Perchlorate and Chloride Solutions over the Temperature Range −45 to 95 °C

“…With cooling of the solutions, all water-originated peaks at 290, 450, and 650 pm become more and more intensive. This finding shows the evolution of partial intrinsic water structure caused by strengthened hydrogen bonds at low temperatures as observed for other supercooled aqueous solutions of LiX (X ) Cl, Br, and I), 5,14,22 Ca(NO 3 ) 2 , 6 and ZnBr 2 . 23 On dilution of the solution to 1 M, the peaks at 290, 450, and 650 pm become enhanced since the contribution from the bulk water is dominant.…”

“…At subzero temperatures the hydrogen bonds among water molecules are strengthened; thus, the intrinsic water structure is partially recovered, as has been seen for aqueous supercooled solutions of mono-and divalent cations and halide ions. 5,14,16,22,23 On the other hand, the hydration shell of Sc 3+ is rigid and should be stable at a temperature as low as -45 °C because of highly positive charge. The partially recovered water structure and stable aqua Sc 3+ probably compromise on a slight increase in coordination number of Sc 3+ as has been observed in the crystal structure of [Sc(H 2 O) 9 ](CF 3 SO 3 ) 3 .…”

NaCl-Induced Phase Separation of 1,4-Dioxane−Water Mixtures Studied by Large-Angle X-ray Scattering and Small-Angle Neutron Scattering Techniques

“…The peak at ∼3.3 Å should be composed of the Cl−O(H 2 O) interactions (3.14 Å) due to Cl - hydration, and the O···O interactions within [Na(H 2 O) 6 ] + (2.4 Å× = 3.4 Å). The shoulder at ∼4.3 Å arises from the O···O interactions among hydrated water molecules within the hydration shell of Cl - . Thus, the NaCl-concentration-dependent features of RDFs for the 1,4-dioxane−water−NaCl mixtures can be reasonably interpreted in terms of the hydration of Na + and Cl - , thus confirming the preferential solvation of the ions by water molecules.…”

“…The shoulder at ∼4.3 Å arises from the O‚‚‚O interactions among hydrated water molecules within the hydration shell of Cl -. 31 Thus, the NaCl-concentration-dependent features of RDFs for the 1,4-dioxane-water-NaCl mixtures can be reasonably interpreted in terms of the hydration of Na + and Cl -, thus confirming the preferential solvation of the ions by water molecules.…”

Molecular beam studies of HCl dissolution and dissociation in cold salty water

“…1 for 5 M NaBr-H 2 O at 298 K. X-ray studies of 5 m LiBr-H 2 O further indicate that Li + Á Á ÁH 2 OÁ Á ÁBr À interactions become more prevalent at lower temperatures. 35 In the absence of ion segregation or depletion at the surface, the 12 mol% LiBr solution creates a summed Br À and Li + surface density of 2.4 Â 10 14 cm À2 , as calculated in the appendix of ref. 23.…”