Sulphur forms

Na COj and Na2S with SO2 or from Na2S03 plus sulphur. Forms many hydrates. Used-in photography ( hypo ) because it dissolves silver halides. Also used in tanning, preparation of mordants, as a fermentation preventative in dyeing and in chemical manufacture. 

In addition to the hydrides of formula HjX, oxygen forms the hydride H2O2, hydrogen peroxide, and sulphur forms a whole series of hydrides called sulphanes. These are yellow liquids which are thermodynamically unstable with respect to hydrogen sulphide and sulphur. 

In addition to the simple acids discussed above, sulphur forms two peroxosulphuric acids containing the —O—O— linkage and a number of thionic acids containing more than one sulphur atom. 

Vulcanisation of rubber Natural rubber becomes soft at high temperature (>335 K) and brittle at low temperatures (<283 K) and shows high water absorption capacity, it Is soluble in non-polar solvents and Is non-resistant to attack by oxidising agents. To improve upon these physical properties, a process of vulcanisation is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 K. On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened. 

It has been suggested that the thiosulphate, a reducing agent, may act as an electron donor and rednce the elemental sulphur formed in Reactions (3.21) and (3.22), forming sulphide ions ... 

Sulphur and selenium unite when warmed with the metal 51 when sulphur is triturated with sodium, the reaction proceeds with explosive violence which can be moderated by dilution with common salt. Under boiling toluene, sulphur forms the trisulphide Na2S3. Selenium forms the monoselenide, Na2Se, when heated with sodium. Sodium is attacked by hydrogen sulphide at ordinary temp., and at the fusion point the metal bums in the gas. Gaseous ammonia reacts readily with sodium, and liquid ammonia forms blue soln.—the so-called alkali-ammoniums. 

According to G. Calcagni, 100 c.c. of a cold 66 per cent, of sodium hydroxide dissolves 24 55 grms. of sulphur or 57 parts of sulphur per 23 parts of sodium while 100 c.c. of a similar soln. of potassium hydroxide dissolves 17 70 grms. of sulphur, or 59 35 parts of sulphur per 39 15 parts of potassium. The soln. reacts for sulphides, polysulphides, thiosulphates, and sulphites. The reaction between alkali hydroxides and sulphur is complex probably sulphides are first formed from which thiosulphates are produced, and by the dissolution of more sulphur, polysulphides the thiosulphates Ipse part of their sulphur forming sulphites. In the more cone. soln. of sulphur part of the latter appears to be uncombined because these soln. yield sulphur to hot benzene. All the soln. are decomposed by carbon dioxide yielding sulphur and hydrogen sulphide. 

In Section 54 ample evidence was given for the existence of stable multiple bonds in the oxides of group II. In this group, sulphur forms a transition to the following group. In the lower oxide SOs two double or semipolar bonds must be assumed... 

The existence of yet another form of sulphur, designated -sulphur, formed together with 77-sulpliur but of a somewhat paler colour, although deeper than octahedral or monoclinie sulphur, is also suspected (see... 

Even in the presence of a large excess of water decomposition only proceeds to the extent of 93-68 per cent., being partly restrained by the presence of the hydrogen chloride formed. The other factor which influences the extent of the action is the sulphur formed by subsequent reaction between the hydrogen sulphide and the sulphur dioxide. Polythionic acids arc formed in solution and the sulphur which separates encloses undecomposed chloride and may also dissolve in it.5... 

Sulphur and Iodine.—Various methods have been described for the preparation of compounds of iodine and sulphur,3 but to-day the products are regarded merely as mixtures of the elements.1 In solution in carbon disulphide, iodine and sulphur exist side by side permanently uncombined. The freezing-point curves for mixtures of the two elements,5 as also the vapour pressure curve of the fusion products,6 likewise give no indication whatever of chemical combination, although sulphur forms a solid solution in iodine. A further proof of the absence of combination is the fact that when dissolved in iodine, sulphur has a normal molecular weight, determined eryoseopically, only a little below that required for S8.7 The present condition of our knowledge, therefore, may be summed up in the statement that no definite compound of sulphur and iodine has yet been obtained.8... 

The bluish-green crystalline mass is very unstable and decomposes fairly rapidly even at the ordinary temperature, giving sulphur dioxide and sulphur. The pure substance may be preserved for several hours in a vacuum. It is hygroscopic, and on absorbing moisture first becomes brown and then deposits sulphur, with concurrent formation of sulphur dioxide, sulphuric acid and possibly other sulphur acids. It is soluble in fuming sulphuric acid, an acid rich in trioxide giving a bluish solution, whilst with less rich acids the solution is brown ordinary pure sulphuric acid causes decomposition. The colour of the brown solution is regarded by some as due to colloidal sulphur formed by partial decomposition of the sesquioxide.6... 

---