Structural Inhomogeneity in Electrolyte Solutions: The Calcium Perchlorate-Water System.

A new approach has been proposed to study the structure of aqueous electrolyte solutions. NIR, Raman and attenuated total reflectance, Fourier transform infra-red (ATR FTIR) spectra have been measured for aqueous calcium perchlorate solutions in the 0.22-4.3 mol·L (0.22-7.46 mol·kg) concentration range at 25 °C. By the methods of principal component analysis (PCA) and multivariate curve resolution-alternating least squares (MCR-ALS) the number, spectra and concentration profiles have been determined for spectroscopically distinguishable forms of water and ClO ion in solutions. The results have been analyzed using a phenomenological model, establishing thereby: concentration ranges for structural rearrangements of the solution, the nature of structural microirregularities and different states of the ClO ion in the areas of domination of the natural water structure, and of cybotactic groups of calcium perchlorate hexa and tetra hydrates. [ABSTRACT FROM AUTHOR]