sulfides include organic and inorganic chemical compounds, a sulfur atom in its molecule is coupled with some metals or non-metals.For inorganic sulphides typical compounds are hydrogen sulfide (H2S), belonging to the class of acids and ammonium sulfide (formula (NH4) 2S), belonging to the class of salts.Also sulfides of metals and nonmetals c KxSy general formula (where K - is a metal or nonmetal cation, and S - acidic hydrogen sulphide residue, x and y - amount of metal cations and anions of the acid moiety in the molecule, respectively), are a class of salts.For example, iron sulfide (II) FeS.Organic sulfides - a chemical substance, a sulfur atom in their molecule associated with hydrocarbon radicals.This mercaptides (thioethers) of the general formula RSR ', and R and R' - hydrocarbon radicals.
All chemical compounds whose molecules metal atom and the atoms of some non-metals (boron, phosphorus P, Si Si, arsenic As), linked to a sulfur atom (S) with a degree of oxidation equal to minus 2, are generally considered to salts of hydrogen sulfideacid H2S.Inorganic sulfides (H2S apart), for example, ammonium sulfide or boron sulfide, is assumed to be an average salts as hydrogen sulphide in the two hydrogen atoms are substituted by other cations.If the hydrogen sulphide only one atom substituted by cations (typical alkaline earth and alkali metal), the salt will be formed acid salt.Examples of inorganic hydrosulfides (bisulfide otherwise) may be compounds such as ammonium hydrosulfide (formula NH4HS) or sodium hydrosulfide (NaHS).Molecules hydrosulfides, unlike sulphides, acid residue or the anion is HS-.Organic hydrosulfide include mercaptans (thiols and thioalcohols) of the general formula RSH, where R - hydrocarbon radical.Mercaptides and mercaptans are characterized by extensive nomenclature, so they require additional consideration.
Most sulfides have a bright color.Readily soluble in water only, and ammonium sulfide, alkali metal sulfides.Almost do not dissolve in water sulphides of other metals.Since the sulfides are hydrogen sulfide salts of weak acids, their water-soluble representatives, may be hydrolyzed.For sulphides formed by metals with a high oxidation state or, if their hydroxides are weak bases (e.g., Cr2S3, Al2S3, etc.), often hydrolysis proceeds irreversibly.Sulfides are mild reducing agents, react with atmospheric oxygen at elevated temperatures to form salts in which the sulfur atom has a higher degree of oxidation, such as sulfates and sulfur dioxide.Ammonium sulfide is used in photography, in the textile industry.Sulfides are used as semiconductor materials, phosphors, in medicine, in agriculture.
sulfides may be produced by different methods.Ammonium sulfide (known as another name of this salt - diammonium sulfide) is prepared by reacting hydrogen sulfide with an excess of ammonia: 2 H2S + NH3 → (NH4) 2S.More resistant acid salt of hydrogen sulfide is FeS iron sulfide, which can only be decomposed by heating in vacuo to obtain it (this is one of many known methods) by an irreversible reaction with sulfur iron: Fe + S → FeS.
The molecular weight of ammonium sulfide and 68.14.e. m. Gross Hill formula system be written as: H8N2S.In appearance resembles salt colorless crystals.Ammonium sulfide at 20 ° C is readily soluble in water.Soluble in ethanol.This hygroscopic substance capable of absorbing moisture.In a free state ammonium sulfide has not been received.Since the (NH4) 2S salt is unstable, the aqueous solutions of its close and hydrogen sulphide thus consist essentially of a mixture of NH3 and NH4HS, and aqueous solutions of (NH4) 2S is a colorless liquid with an odor of ammonia and hydrogen sulfide.The reaction solution is alkaline with a pH of 9.3.The crystals of the solid salt is impossible to distinguish, even in strong cooling of the solution.As a result of air oxidation and the formation of polysulfide, ammonium sulfide solution rapidly turns yellow.Therefore sulfide solution should be stored in a flask, filled up to the stopper and tightly sealed.
The molecular weight of ammonium hydrosulfide and 51.11.e. m. Gross Hill formula system be written as: H5NS.Salt in appearance is a colorless rhombic crystals.The density of salt equal to 0.89 g / cm3.Melting point 120 ° C (under pressure).At room temperature the evaporation and sublimation of the reagent vapor.This compound is volatile at room temperature.The substance is easily soluble in ethyl alcohol and cold water, hot water or heated with little splits.Reactions aqueous alkaline salt solution.In the air is capable of ammonium hydrosulfide is oxidized, so it from a colorless solution in storage is rapidly becoming yellow due to the formation of polysulfides.Ammonium hydrosulfide may be prepared directly by reaction with ammonia in diethyl sulfide (sulfur), or by passing air at 0 ° C in a solution of ammonia excess hydrogen sulfide by the reaction equation: NH3 + H2S → NH4HS.
