SPECTROSCOPIC AND CHROMATOGRAPHIC INVESTIGATIONS OF SULFUR AMMONIA SOLUTIONS

Elemental sulfur dissolves in liquid ammonia to form an anionic adduct S5NH2- (sulfur in zero oxidation state) which by redox reactions lead s to the anionic species S3N- and S4N- (positive oxidation state), and S-3(-) as well as its dimer S-6(2-) (negative oxidation state). By an ion exchange chromatography under HPLC conditions the species of a sul fur ammonia solution (SAS) are separated and (using radioactive sulfur ) their absolute concentrations and absorption spectra are obtained. W ith these the absorption spectra of SAS taken in wide concentration an d temperature ranges are analysed without separation to get quantitati ve data of the concentrations of all species and thus of the equilibri um constants, the reaction enthalpies and entropies of the two reactio ns in which the species are involved. The variations of the spectra du e to shifts of the equilibria by changes of the pH of the solutions or by changes of their redox potential are simulated. Finally the time d ependence of the spectra during the slow dissolution process of sulfur in ammonia gives information on the solubilization process.