Potassium trisulphide

J. J. Berzelius said anhydrous potassium trisulphide appears in yellowish-brown masses which, said H, E. Schone, show the presence of prismatic crystals on a fractured surface. W. Biltz and E. Wilke-Dorfurt say the anhydrous... 

Apparent indicator constant 264, 267 Apparent stability constant 59 Aqua regia 111 Arc alternating current, 764 direct current, 763, 771 sensitivities of elements, (T), 766 Aromatic hydrocarbons analysis of binary mixtures, 715 Arsenates, D. of (ti) 357 Arsenic, D. of as silver arsenate, (ti) 357 as trisulphide, (g) 448 by iodine, (am) 634, (ti) 397 by molybdenum blue method, (s) 681 by potassium bromate, (ti) 406 by potassium iodate, (ti) 401 in presence of antimony, (s) 724 Arsenic(III) oxide as primary standard, 261... 

Hydrogen trisulphide is much more easily combustible than the crude parent hydrogen polysulphide. Exposure to light tends to accelerate its decomposition. It slowly reduces concentrated sulphuric acid to sulphur dioxide, whilst on contact with dry silver oxide, cupric oxide, lead dioxide or mercuric oxide, it bursts into explosive combustion,2 a residue of the metallic sulphide being obtained. Many other metallic oxides and most salts bring about a less vigorous decomposition metals in the massive condition only react with it slowly. With potassium permanganate or dichromate the reaction is violent. 

By the action of chlorine and chlorine compounds on the sulphides of arsenic. By passing chlorine over the dry sulphides, realgar or orpiment, at 130° to 140° ., theoretical yields of arsenic trichloride and of sulphur dichloride are obtained.5 The trisulphide reacts with hydrogen chloride in the cold, but chlorination by means of hydrochloric acid is difficult, only a small quantity of the chloride being volatilised.7 The reaction is facilitated by the presence of ferric chloride,8 cuprous chloride or potassium antimonyl tartrate.9 Other chlorinating agents, effective with the sulphides, are sulphur mono-chloride,10 a mixture of ammonium chloride and nitrate,11 and mercuric chloride.12... 

Many other methods of preparation have been employed. For example, the triiodide is formed when arsenious oxide,5 or a mixture of this oxide with sulphur,6 is heated in iodine vapour or when arsenious oxide is heated with iodine,7 hydriodic acid,8 a mixture of potassium iodide and acetic acid,9 or a mixture of potassium iodide and potassium hydrogen sulphate.10 When arsenic disulphide and iodine, in the proportions 1 As Ss 3la, are heated together, arsenic triiodide is formed.11 When arsenic trisulphide is fused with an excess of iodine, the product is soluble in carbon disulphide and the solution on evaporation deposits arsenic triiodide, then a sulphiodide and finally sulphur with excess of sulphide the product is the sulphiodide, AsS2I. If a solution of iodine in carbon disulphide is added to arsenic di- or tri-sulphide, the triiodide and sulphur are formed. The triiodide is also produced when a mixture of the trisulphide and mercuric iodide is heated 12. when hydriodic... 

Chemical Properties.—Arsenic trisulphide may be reduced to arsenic by heating in a stream of hydrogen the arsenic sublimes. The reaction begins at about 300° C.,10 but proceeds more readily if the sulphide is first fused with an alkali carbonate.11 A similar reduction occurs when the sulphide is heated with a mixture of charcoal and alkali carbonate12 or lime when heated with potassium cyanide,13 an oxalate14 or with a metal such as silver or iron the latter if in excess yields arsenide. 

The trisulphide reacts with sulphur dioxide at temperatures between 300° and 800° C. to form sulphur and a sulphate,10 whilst if the sulphide is digested with an aqueous solution of sulphur dioxide, or of potassium hydrogen sulphite, it dissolves and the solution when boiled evolves... 

Ruthenium Trisulphide, RuS, is obtained by passing hydrogen sulphide through an aqueous solution of potassium chlor-ruthenate at 0° C. It is formed as a yellowish brown precipitate. When dry it readily oxidises in air, becoming heated to incandescence for this reason the sulphide is dried in an atmosphere of an inert gas.e... 

The trisulphide, K2S3J is formed by the action of excess of sulphur on a solution of potassium in liquid ammonia.5 The tetrasulphide, K2S4, the most stable member of the series, can be prepared by heating a mixture of potassium carbonate and sulphur at 800° C. in a current of carbon dioxide,6 or by the action of hydrogen sulphide on the fused pentasulphide. It yields an octahydrate, a trihydrate, and a semihydrate. Its heat of formation from the elements is 116-6 Cal.7... 

Compounds Bis-dimethylstibinyl oxide Bis(dimethylthallium) acetylide Butyllithium Nonacarbonyldiiron Octacarbonyldicobalt Pentacarbonyliron Tetracarbonylnickel Dibismuth trisulphide Dicaesium selenide Dicerium trisulphide Digold trisulphide Europium (II) sulphide Germanium (II) sulphide Iron disulphide Iron (II) sulphide Manganese (II) sulphide Mercury (II) sulphide Molybdenum (IV) sulphide Potassium sulphide Rhenium (VII) sulphide Silver sulphide Sodium disulphide Sodium polysulphide Sodium sulphide Tin (11) sulphide Tin (IV) sulphide Titanium (IV) sulphide Uranium (IV) sulphide ... 

This brownish powder, which is somewhat unstable in the air, ajid which is soluble in potassium sulpiride solution, is also obtained in small quantity by the interaction of molybdenum trisulphide and potassium sulphide. 

Potassium chlorate becomes quite sensitive in contact with red phosphorus and ignites very easily by friction. These properties are used in match. When it is mixed with sulphur or compounds of sulphur like realgar, antimony trisulphide etc., the sensitivity to shock or friction is highly increased. According to the late professor S.Yamamoto of Tokyo University, when a mixture of potassium chlorate and realgar was shaped into a small tablet in a hand press and left on a table, a little while later the tablet caused spontaneous ignition and burnt out. He tried the same tests sevejjral times and the results were the same. He concluded that it was caused by inner friction which occurs with the recovery of the stress produced by the press(s. Yamamoto Studies in safety in firework manufacture 1(1959)3 ... 

Potassium perchlorate becomes sensitive in contact with red phosphorus the mixture detonates with a loud noise by an impact between metal pieces of aluminium or bronze. When the mixture is ignited, it detonates instantaneously. However match or toy pistol caps cannot be made from compositions which contain potassium perchlorate in place of chlorate, because the ignition is uncertain. When potassium perchlorate is mixed with realgar, antimony trisulphide, sulphur etc. it also becomes sensitive realgar particularly increases the sensitivity to friction. But the degree of sensitivity is not as large as it is with potassium chlorate. 

When ammonium perchlorate is mixed with red phosphorus it becomes very sensitive to shock, but not so much to friction. With realgar, sulphur, antimony trisulphide etc. it also becomes sensitive almost like the above. The degree of shock sensitivity of ammonium perchlorate due to such substances is almost the same as that of potassium chlorate, but higher than that of potassium perchlorate. The low friction sensitivity of ammonium perchlorate due to these substances is one of its attractive features in comparison with potassium chlorate and perchlorate(T.Shimizu Sensitivity tests on firework compositions, J. Exp.Soc. Japan, 2, No.6, p. 3 3... 

Antimony trisulphide burns in combination with ammonium perchlorate producing a slightly green flame(in the case of sulphur a slightly red flame) and can generate red brown smoke in combination with potassium nitrate and charcoal. 

The wet process is used for manufacturing cracker balls(the composition consists of realgar and potassium chlorate), paper caps (red phosphorus, sulphur and potassium chlorate) and pull-igniters (red phosphorus, antimony trisulphide and potassium chlorate). 

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