A Reaction Involving Oxygen and Metal Sulfides William D. Hill, Jr. North Carolina Central University. Durham. NC 27707 The setun in which oxveen. .- . "eenerated hv the thermal decomposition of potassium chlorate in the presence of maneanese dioxide. reacted with various metal sulfides. is shown Fn the figure. ' The sulfides were preheated before subjection to a reaction with oxygen. Each burner was kept oscillating during the reaction and the ~ o t a s s i u mchlorate-manganese dioxide comhination was heated slowly to minimize spattering and to cut down on the chances of this combination to come into contact with the ruhhrr stopper in which a violent exoergic reaction would take place after the comhination melted. The bright glow or combustion observed as each sulfide reacted with excess oxygen ceased when the reactions were completed. The results are in the table. inclusive of the weiehts of the products after the completed reactions. 'l'he pn~ductswere identified by stoichinmetric relationships, their appearance, and magnetic propertiesi where appropriate. Sulfur dioxide was nroduced in each reaction iust as it was when oxygen reacted kith zinc sulfide,%and this-was indicated by the changing of blue litmus paper to red. No water was siphoned in the collection of sulfur dioxide since the perpendicular bent glass tube was above the level in the container where sulfur dioxide was collected. The oxygen-metal sulfide reactions based on the reaction involving oxygen and zinc sulfide2 fall into two categories.
The experimental seNp
Bas, CaS, K2S, and SrS are converted to the respective peroxides, products also obtained when oxygen reacts with Ba, Ca, K, and The other sulfides are converted to metal oxides. There are pronounced color changes in each reaction even the ones involving Bas, CaS, KgS, SrS, and SnS where the weight change is very little.
'
Anders and Sonnessa "Principles Of Chemistry: An Introduction toTheoretical Concepts"; Macmillan: New York, 1965; p 91. Nebergall. Holtzclaw, and Schmidt "College Chemistry With QualitativeAnalysis". 5th ed.; Heath: Lexington. MA. 1976; p 158. Nebergall. Holtzclaw, and Robinson "General Chemistry", 6th ed.; Heath: Lexington, MA, 1980; pp 191 and 192.
The Results
Amount Metal sulfide SbrSs Bas CaS FeS MOSI KIS SrS SnS
moi
9 16.4750 16.9320 7.2080 8.7850 6.0000 5.5010 5.9815 7.5850
0.05 0.10 0.10 0.10 0.05 0.05 0.05 0.05
16.4742 16.9322 7.2054 7.7181 7.1966 5.4989 5.9606 7.5338
yellow grayish yellow off white gray. ferromagnetic off yellow white off white white
Volume 63 Number 5 May 1986
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