Properties of fused polysulphides—IV. Cryoscopic studies on solutions of alkali metal polysulphides in potassium thiocyanate

✍ Scribed by B. Cleaver; A.J. Davies

• Publisher: Elsevier Science
• Year: 1973
• Tongue: English
• Weight: 371 KB
• Volume: 18
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(73)80065-9

✦ Synopsis

Measurements have been made of the depression of the freezing point of fused KSCN by Naps, Na&.+ and KzS~.~. Na2S gives a freezing point depression corresponding to three foreign particles. Theseare believed to be 2Na+ and CN-, thecyanide ion being formed by reaction of S*-with the solvent. Na2SI.4 and K2!& give opaque solutions in KSCN which are initially dark blue-green, and which slowly lose sulphur vapour and change colour to blue and finally to pale yellow. The initial freezing point depressions correspond to 4 and 2 foreign particles respectively, but when sulphur evolution is complete the final depressions correspond to 2 and 0 foreign particles. The following schemes are consistent with the observations M&,(S) -2M+ + Sb2-slow -2M+ + 2St + K&(s) M&(S) -2M+ + S5'-slow -2M+ + 3St + K&(S) M&(S) -2M+ + Se=-(M = Na or K).