Simple hydrated salts in methanolic and aqueous solutions - Acoustic and spectroscopic studies

•Three selected inorganic hydrated salts in water and methanol solutions were acoustically and spectroscopically investigated.•All investigated electrolytes are strong in aqueous solutions but weak in methanol.•Substantial differences of the coordination abilities of the cations are manifested, especially in acoustic properties.

Hydrated salts, MgCl2·6H2O, CuCl2·2H2O and EuCl3·6H2O when dissolved in methanol, conserve their original coordination numbers, probably dissociating two chloride anions (magnesium chloride), stepwise in equilibrium reactions (copper chloride) or probably only one Cl− (europium chloride). Water hydrating molecules are almost fully removed from the coordination shell only in the case of MgCl2·6H2O. The above conclusions were drawn from analyzing the acoustic and densimetric properties of the title systems and confirmed by conductivity tests. The results are also compared to those in aqueous solutions. The emission and excitation spectra obtained for europium chloride were applied as spectroscopic probes of solution structure, as well as of the number of existing species and their symmetries.

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