Determination of sulphur species arising from the reaction of sulphur and sulphide in a (K, Na)SCN eutectic melt

Sulphur and sulphide ions react in (K,Na)SCN eutectic melt with the formation of polysulphide. The electrolytic oxidation of SCN(-) at 155 degrees forms S(4) which gives S(2-)(5) with S(2-); at 165 degrees the sulphur electrogenerated is S(2) that reacts according to S(2) + S(2-) = S(2-)(3). The equilibrium constants of these reactions have been obtained by voltammetric measurements. The formation of S(2) at 155 degrees by irradiation from a xenon lamp was confirmed. The S(2) reacts with S(2-) to give S(2-)(3), and the equilibrium constant for this reaction is the same as that found for the reaction at 165 degrees .