Sulphur halide oxides

A number of halide oxides are formed by sulphur and selenium but only one is considered here. 

Nickel forms yellow anhydrous halides NiXjlX = F. Cl. Br) and a black iodide Nil2 all these halides are made by direct combination of the elements, and the chloride by reaction of sulphur dichloride oxide with the hydrated salt. All dissolve in water to give green solutions from which the hydrates can be crystallised the solutions contain the ion [NifHjOls], and the chloride crystallises as NiCl2.6H2O, nickel(II) chloride hexahydrate. 

Sulphur(Vl) forms the oxide chloride S02C12, sulphuryl chloride see sulphuryl halides). 

Sulfur oxides produce sulphurous/sulfuric acid. Because oxygen and halides are often also present, high-nickel alloys are required. 

A final group of reactions are those involving water. A wide variety of materials such as the alkali metals light metals and their hydrides strong acids, such as sulphuric acid anhydrous metal oxides anhydrous metal halides and non-metal oxides ail react vigorously or violently with water under various circumstances. 

The same goes for propane and butane. Nitrogen oxide, hydrogen halides, and vinyl bromide stabilise acetylene, but sulphur dioxide destabilise it. 

In this state, chromium compounds are usually coloured yellow or red (but due to charge transfer (p. 60) and not to the presence of d electrons on the chromium ion). The only halide known is the unstable chromium(VI) fluoride CrF6, a yellow solid. However, oxide halides are known, for example Cr02Cl2 ( chromyl chloride ), formed as a red vapour when concentrated sulphuric acid is added to a chromate(VI) (or dichromate) mixed with a chloride ... 

The most important range for inorganio chemicals is between 1 40 and 1 70. But there are some substances, such as certain oxides and sulphides, whose indices lie well above this range, or even well above 2 0. Media which are liquid at room temperature and have such high refractive indices are not available, but certain mixtures of substances which solidify to glasses may be used. A little of the medium is melted on a microscope slide, the substance under examination is dusted into the melt, a cover-glass is pressed on, and the slide is then allowed to cool. Substances which have been used in this way are mixtures of piperine with arsenic and antimony tri-iodides (for indices 1 7-2 1), mixtures of sulphur and selenium (2-0-2-7)—for details, see Larsen and Berman (1934)—and mixtures of the halides of thallium (Barth, 1929). 

The pentavalent halides and oxyhalides, as in the case of other niobium compounds, are the most stable. It is remarkable that the pentavalency is maintained with increase in the atomic weight of the halogen. All the halogen compounds are characterised by their ready tendency to undergo hydrolysis on the addition of water or even in damp air with precipitation of niobie acid and formation of the hydrogen halide. Their preparation can, therefore, be effected only in the dry way (a) synthetically, or (b) by the action of chlorine, carbon tetrachloride, or sulphur monochloride on the oxide or sulphide. They do not possess saline properties, and cannot be prepared by the action of the halogen acids on the oxide. 

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