Lithium Halides Lab Report

We have analysed the solvation structure of lithium halides in methanol-water mixed solvent. Water-methanol mixtures show several interesting nonideal properties which leads to changes in the structure and dynamics of the mixtures at molecular level [93]. A number of experimental and theoretical studies have been carried out on water-methanol mixtures in order to investigate the changes of their microscopic structural and dynamical properties and to gain insights into the coordination shell of the ions [94-97]. These studies have revealed microscopic details of the solvation structure of water and methanol molecules in their mixtures. In particular, formations of strong water-methanol hydrogen-bonded complexes are believed to play a significant role in …show more content…

Hydrogen-bonded molecules of methanol form zig-zag polymer chains. Though in binary mixture the molecules of methanol and water may form a common hydrogen-bonded network the bulky methyl group causes that methanol molecule cannot simply replace the water molecule in the tetrahedral structure [100]. In consequence the methanol-water mixture may become heterogeneous on the molecular level. Neutron diffraction and X-ray spectroscopy have confirmed that supposition [101, 102]. Despite apparent miscibility of both components, methanol and water clusters are observed over whole concentration range. At particular concentration, near 25-27 mol% of methanol, where transport and thermodynamic properties exhibit extrema, water and methanol form separate, percolating structures. Several experimental techniques were employed to investigate solvation of ions in methanol-water mixtures. Results are, however, inconsistent and lead to contradict conclusions. Therefore both preferential hydrations, as well as a lack of preferences have been postulated for alkali and halide ions in methanol-water