Bisulfide (or bisulphide in British English) is an

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

HS⁻ (also written as SH⁻). It contributes no color to bisulfide salts, and its salts may have a distinctive putrid smell. It is a strong base. Bisulfide solutions are corrosive and attack the skin. It is an important chemical reagent and an industrial chemical, mainly used in paper pulp industry (

Kraft process The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chip ...

), textiles, synthetic flavors, coloring brasses, and iron control.

Properties

A variety of salts are known, including

sodium hydrosulfide Sodium hydrosulfide is the chemical compound with the formula NaHS. This compound is the product of the half-neutralization of hydrogen sulfide () with sodium hydroxide (NaOH). NaSH and sodium sulfide are used industrially, often for similar purpos ...

and

potassium hydrosulfide Potassium hydrosulfide is the inorganic compound with the formula KSH. This colourless salt consists of the cation and the bisulfide anion . It is the product of the half-neutralization of hydrogen sulfide with potassium hydroxide. The compound ...

Ammonium hydrosulfide Ammonium hydrosulfide is the chemical compound with the formula . Composition It is the salt derived from the ammonium cation and the hydrosulfide anion. The salt exists as colourless, water-soluble, micaceous crystals. On Earth the compound ...

, a component of "stink bombs" has not been isolated as a pure solid. Some compounds described as salts of the

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

dianion contain primarily hydrosulfide. For example, the hydrated form of

sodium sulfide Sodium sulfide is a chemical compound with the formula Na2 S, or more commonly its hydrate Na2S·9 H2O. Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are gener ...

, nominally with the formula , is better described as . Aqueous bisulfide absorbs light at around 230 nm in the UV–visible spectrum. Using this approach, bisulfide has been detected in the ocean and in sewage. Bisulfide should not be confused with the

disulfide In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

dianion, , or ⁻S–S⁻.

Basicity

The bisulfide anion can accept a proton: Because of its affinity to accept a

proton A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...

(H⁺), bisulfide has a basic character. In aqueous solution, it has a corresponding p''K''_a value of 6.9. Its

conjugate acid A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...

(). However, bisulfide's basicity stems from its behavior as an

Arrhenius base Arrhenius may refer to * Birgit Arrhenius (born 1932), Swedish archaeologist * Carl Axel Arrhenius (1757–1824), Swedish army lieutenant and amateur mineralogist who discovered ytterbite, a mineral that led to the discovery of yttrium by Johan Gad ...

. A solution containing spectator-only counter ions, has a basic pH according to the following acid-base reaction:

Chemical reactions

Upon treatment with an acid, bisulfide converts to

. With strong acids, it can be doubly protonated to give . Oxidation of bisulfide gives sulfate. When strongly heated, bisulfide salts decompose to produce

salts and hydrogen sulfide.

Biochemistry

At physiological pH, hydrogen sulfide is usually fully ionized to bisulfide (HS⁻). Therefore, in biochemical settings, "hydrogen sulfide" is often used to mean, bisulfide. Hydrosulfide has been identified as the third gasotransmitter along with nitric oxide and carbon monoxide.

Other derivatives

SH⁻ is a soft anionic

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

that forms complexes with most metal ions. Examples include u(SH)₂sup>− and (C₅H₅)₂Ti(SH)₂, derived from

gold(I) chloride Gold(I) chloride is a compound of gold and chlorine with the chemical formula AuCl. Preparation Gold(I) chloride is prepared by thermal decomposition of gold(III) chloride. Reactions Although there is a region of stability at higher temperatures ...

and

titanocene dichloride Titanocene dichloride is the organotitanium compound with the formula ( ''η''5-C5H5)2TiCl2, commonly abbreviated as Cp2TiCl2. This metallocene is a common reagent in organometallic and organic synthesis. It exists as a bright red solid that slowl ...

, respectively.

Safety

Bisulfide salts are

corrosive A corrosive substance is one that will damage or destroy other substances with which it comes into contact by means of a chemical reaction. Etymology The word ''corrosive'' is derived from the Latin verb ''corrodere'', which means ''to gnaw'', ...

, strongly alkaline and release toxic hydrogen sulfide upon acidification.

References

{{Reflist Anions Sulfur ions Acid–base chemistry hu:Hidrogénszulfid