Magnesium sulphide

Berenson and Wranglen have suggested that the presence of magnesium sulphide inclusions in ductile cast irons may act as corrosion-initiating sites and may therefore make ductile iron more liable to corrosion than grey iron but this view has been contested by Collins . 

Kupec et al. [180] determined total sulphur in sludge by a method involving magnesium reduction in which the sample is heated with magnesium powder to convert all sulphur compounds into magnesium sulphide. The magnesium sulphide is treated with sulphuric acid and the evolved hydrogen sulphide determined by iodometric titration. 

Chlorides. — Dissolve 1 gm. of magnesium sulphide in 20 cc. of water, and add 1 cc. of nitric acid the. solution should not be affected by silver nitrate solution. 

Beryllium burns in sulphur vapour forming BeS. This cannot be made in the wet way, though, like BeO, it is unrcactivc to water. Magnesium sulphide, similarly made, hydrolyses rapidly ... 

Konczewicz L, Bigenwald P, Cloitre T et al (1996) MOVPE growth of zincblende magnesium sulphide. J Cryst Growth 159 117-120... 

Potassium sulphide K2S, sodium sulphide Na2S, barium sulphide BaS and magnesium sulphide MgS attack aluminium. Calcium sulphide has a more moderate action aluminium vessels have been used for the transport and the spreading of mixtures containing up to 20% calcium sulphate and some iron sulphate. 

Magnesium does not occur in nature as sulphide because itm is a soft base and therefore, magnesium sulphide (MgS) is not so stable. 

Prepare a saturated solution of sodium sulphide, preferably from the fused technical sodium polysulphide, and saturate it with sulphur the sulphur content should approximate to that of sodium tetrasulphide. To 50 ml. of the saturated sodium tetrasulphide solution contained in a 500 ml. round-bottomed flask provided with a reflux condenser, add 12 -5 ml. of ethylene dichloride, followed by 1 g. of magnesium oxide to act as catalyst. Heat the mixture until the ethylene dichloride commences to reflux and remove the flame. An exothermic reaction sets in and small particles of Thiokol are formed at the interface between the tetrasulphide solution and the ethylene chloride these float to the surface, agglomerate, and then sink to the bottom of the flask. Decant the hquid, and wash the sohd several times with water. Remove the Thiokol with forceps or tongs and test its rubber-like properties (stretching, etc.). 

Crucibles fitted with permanent porous plates are cleaned by shaking out as much of the solid as possible, and then dissolving out the remainder of the solid with a suitable solvent. A hot 0.1 M solution of the tetrasodium salt of the ethylenediaminetetra-acetic acid is an excellent solvent for many of the precipitates [except metallic sulphides and hexacyanoferrates(III)] encountered in analysis. These include barium sulphate, calcium oxalate, calcium phosphate, calcium oxide, lead carbonate, lead iodate, lead oxalate, and ammonium magnesium phosphate. The crucible may either be completely immersed in the hot reagent or the latter may be drawn by suction through the crucible. 

Traces of many metals interfere in the determination of calcium and magnesium using solochrome black indicator, e.g. Co, Ni, Cu, Zn, Hg, and Mn. Their interference can be overcome by the addition of a little hydroxylammonium chloride (which reduces some of the metals to their lower oxidation states), or also of sodium cyanide or potassium cyanide which form very stable cyanide complexes ( masking ). Iron may be rendered harmless by the addition of a little sodium sulphide. 

Appreciable errors may also be introduced by post-precipitation. This is the precipitation which occurs on the surface of the first precipitate after its formation. It occurs with sparingly soluble substances which form supersaturated solutions they usually have an ion in common with the primary precipitate. Thus in the precipitation of calcium as oxalate in the presence of magnesium, magnesium oxalate separates out gradually upon the calcium oxalate the longer the precipitate is allowed to stand in contact with the solution, the greater is the error due to this cause. A similar effect is observed in the precipitation of copper or mercury(II) sulphide in 0.3M hydrochloric acid in the presence of zinc ions zinc sulphide is slowly post-precipitated. 

Aluminium B a 5 o B B < I Antimony a < Barium B a 1 3 Bismuth I Boron Cadmium 1 Caesium Calcium 1 Cerium Chloride, Chlorine [ Chromium X) o o C o a Gallium I Germanium Gold 1 Hafnium Hydrogen sulphide B a 5 a B a 5 a o 1 Lanthanons Lead f Lithium 1 Magnesium f Manganese Mercury Molybdenum... 

Diethyl magnesium Caesium Iron (II) sulphide lododimethylarsine... 

Dimethyl magnesium Iridium Rhenium (VII) sulphide non-metals... 

Sulphur/metal mixtures form metal sulphides. The reaction can be very violent. This is the case for lithium or magnesium when both the metal and sulphur are in the molten state. This is also true for sodium by heating. The reaction is much less violent when sodium chloride is present. It is also less dangerous if the interaction is made in toluene. 

Copper (II) sulphide is like any other sulphide, ie very reactive vis- -vis oxidants. Therefore detonations occur during mixtures between this compound and magnesium, zinc and cadmium chlorates. 

Post-precipitation involves the deposition of a sparingly soluble impurity of similar properties to the precipitate on the surface of that precipitate after it has been formed. It is particularly a problem where similar materials are being separated on the basis of their different rates of precipitation, e.g. calcium and magnesium oxalates or zinc and mercury sulphides. Copreci-... 

The reaction of cis- and frans-stilbene oxides with phenylphosphonothioic dichloride in the presence of magnesium gives cis- and fra/ts-stilbene and (7).13 Phenylphosphinidene sulphide is postulated as being an intermediate. The zwitterion (8) bears a remarkable similarity to the controversial perepoxides which are thought to be intermediates in the reaction of singlet oxygen with alkenes. 

The electrical conductivities of soln. of a great many compounds in liquid hydrogen halides have been measured by E. H. Archibald and D. McIntosh. The conductivity is raised considerably by phosphoryl chloride. Sodium sodium sulphide, borate, phosphate, nitrate, thiosulphate, and arsenate chromic anhydride potassium nitrate, hydroxide, chromate, sulphide, bisulphate, and ferro- and ferri- cyanide ammonium fluoride and carbonate j rubidium and caesium chloride magnesium sulphate calcium fluoride ... 

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