Potassium thiosulfate

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Potassium thiosulfate
PotS2O3.svg
Names
Other names
  • Dipotassium monothiosulfate
  • KTS
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.593 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-666-8
PubChem CID
UNII
  • InChI=1S/2K.H2O3S2/c;;1-5(2,3)4/h;;(H2,1,2,3,4)/q2*+1;/p-2
    Key: FGRVOLIFQGXPCT-UHFFFAOYSA-L
  • [O-]S(=O)(=S)[O-].[K+].[K+]
Properties
K2S2O3
Molar mass 190.32 g/mol
AppearanceWhite solid
Density 2.37 g/cm3
96.1 g/100 ml (0 °C)
155.4 g/100 ml (20 °C)
165 g/100 ml (25 °C)
175.7 g/100 ml (30 °C)
204.7 g/100 ml (40 °C)
215.2 g/100 ml (50 °C)
238.3 g/100 ml (60 °C)
255.2 g/100 ml (70 °C)
293.1 g/100 ml (80 °C)
312 g/100 ml (90 °C) [1]
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H315, H319
P264, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362
Related compounds
Other anions
Potassium sulfite; Potassium sulfate
Other cations
Sodium thiosulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Potassium thiosulfate, commonly abbreviated KTS, is an inorganic compound with the formula K2S2O3. This salt can form multiple hydrates, such as the monohydrate, dihydrate, and the pentahydrate, all of which are white or colorless solids. [1] It is used as a fertilizer.

Contents

Formation and reactions

Thiosulfate salts are produced by the reaction of sulfite ion with elemental sulfur, and by incomplete oxidation of sulfides. For example, this salt is produced by reacting potassium hydroxide with ammonium hydroxide, sulfur dioxide, and elemental sulfur. [2] Thiosulfates are stable in neutral or alkaline solutions, but not in acidic solutions, due to disproportionation to sulfur dioxide and sulfur: [3]

S
2
O2−
3
+ 2 H+ → SO2 + "S" + H2O

Due to this property, it can sequester metals, especially iron. [2]

Thiosulfate reacts with iodine to give tetrathionate, in this case potassium thiosulfate reacts with iodine to produce potassium tetrathionate and potassium iodide:

2 K2S
2
O
3
+ I2 → K2S
4
O
6
+ 2 KI

Thiosulfate extensively forms diverse complexes with transition metals. In the era of silver-based photography, thiosulfate was consumed on a large scale as a "stop" reagent. This application exploits thiosulfate's ability to dissolve silver halides. Thiosulfate is also used to extract or leach gold (sodium thiosulfate) and silver from their ores as a less toxic alternative to cyanide. [3]

Uses

Potassium thiosulfate is commonly used as a fertilizer alone or with urea and/or urea ammonium nitrate [4] due to its ability to delay nitrification. [2] It thus has the ability to reduce the emission of nitrous oxide. [5] It can also reduce the amount of fumigants being released from the soil. [6] If used alone it is used in very dilute solution due to its ability to cause phytotoxicity symptoms. This is caused by the elemental sulfur being oxidized to produce sulfuric acid. [4]

Related Research Articles

<span class="mw-page-title-main">Sulfur</span> Chemical element, symbol S and atomic number 16

Sulfur (also spelled sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature.

<span class="mw-page-title-main">Sodium sulfite</span> Chemical compound

Sodium sulfite (sodium sulphite) is the inorganic compound with the chemical formula Na2SO3. A white, water-soluble solid, it is used commercially as an antioxidant and preservative. A heptahydrate is also known but it is less useful because of its greater susceptibility toward oxidation by air.

<span class="mw-page-title-main">Sodium thiosulfate</span> Chemical compound

Sodium thiosulfate is an inorganic compound with the formula Na2S2O3·xH2O, where x indicates the number of water molecules in the compound. Typically it is available as the white or colorless pentahydrate, Na2S2O3·5H2O. The solid is an efflorescent crystalline substance that dissolves well in water.

In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. The reverse of disproportionation, such as when a compound in an intermediate oxidation state is formed from precursors of lower and higher oxidation states, is called comproportionation, also known as synproportionation.

In horticulture, lime sulphur (American spelling lime sulfur) is mainly a mixture of calcium polysulfides and thiosulfate (plus other reaction by-products as sulfite and sulfate) formed by reacting calcium hydroxide with elemental sulfur, used in pest control. It can be prepared by boiling in water a suspension of poorly soluble calcium hydroxide (lime) and solid sulfur together with a small amount of surfactant to facilitate the dispersion of these solids in water. After elimination of any residual solids (flocculation, decantation and filtration), it is normally used as an aqueous solution, which is reddish-yellow in colour and has a distinctive offensive odour of hydrogen sulfide (H2S, rotten eggs).

<span class="mw-page-title-main">Sodium dithionate</span> Chemical compound

Sodium dithionate Na2S2O6 is an important compound for inorganic chemistry. It is also known under names disodium dithionate, sodium hyposulfate, and sodium metabisulfate. The sulfur can be considered to be in its +5 oxidation state.

<span class="mw-page-title-main">Potassium metabisulfite</span> Chemical compound

Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent odour. It is mainly used as an antioxidant or chemical sterilant. As a disulfite, it is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably. Potassium metabisulfite has a monoclinic crystal structure.

<span class="mw-page-title-main">Thiosulfate</span> Polyatomic ion (S2O3, charge –2)

Thiosulfate is an oxyanion of sulfur with the chemical formula S2O2−3. Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, e.g. sodium thiosulfate Na2S2O3. The prefix thio- indicates that the thiosulfate is a sulfate with one oxygen replaced by sulfur. Thiosulfate is tetrahedral at the central S atom. Thiosulfate salts occur naturally. Thiosulfate ion has C3v symmetry, and is produced by certain biochemical processes. It rapidly dechlorinates water and is notable for its use to halt bleaching in the paper-making industry. Thiosulfate salts are mainly used in dying in textiles and the bleaching of natural substances.

<span class="mw-page-title-main">Potassium bisulfite</span> Chemical compound

Potassium bisulfite (or potassium hydrogen sulfite) is a chemical mixture with the approximate chemical formula KHSO3. Potassium bisulfite in fact is not a real compound, but a mixture of salts that dissolve in water to give solutions composed of potassium ions and bisulfite ions. It is a white solid with an odor of sulfur dioxide. Attempts to crystallize potassium bisulfite yield potassium metabisulfite, K2S2O5.

The sulfite process produces wood pulp that is almost pure cellulose fibers by treating wood chips with solutions of sulfite and bisulfite ions. These chemicals cleave the bonds between the cellulose and lignin components of the lignocellulose. A variety of sulfite/bisulfite salts are used, including sodium (Na+), calcium (Ca2+), potassium (K+), magnesium (Mg2+), and ammonium (NH4+). The lignin is converted to lignosulfonates, which are soluble and can be separated from the cellulose fibers. For the production of cellulose, the sulfite process competes with the Kraft process which produces stronger fibers and is less environmentally costly.

<span class="mw-page-title-main">Thiosulfate dehydrogenase</span>

Thiosulfate dehydrogenase is an enzyme that catalyzes the chemical reaction:

<span class="mw-page-title-main">Sable Chemicals</span>

Sable Chemical Industries Limited is the sole manufacturer of ammonium nitrate (NH4NO3) in Zimbabwe.

<span class="mw-page-title-main">Calcium bisulfite</span> Chemical compound

Calcium bisulfite is an inorganic compound which is the salt of a calcium cation and a bisulfite anion. It may be prepared by treating lime with an excess of sulfur dioxide and water. As a food additive it is used as a preservative under the E number E227. Calcium bisulfite is an acid salt and behaves like an acid in aqueous solution. It is used in the sulfite process for producing paper from wood chips.

Sulfur is metabolized by all organisms, from bacteria and archaea to plants and animals. Sulfur can have an oxidation state from -2 to +6 and is reduced or oxidized by a diverse range of organisms. The element is present in proteins, sulfate esters of polysaccharides, steroids, phenols, and sulfur-containing coenzymes.

<span class="mw-page-title-main">Ammonium sulfite</span> Chemical compound

Ammonium sulfite is the ammonium salt of sulfurous acid with the chemical formula (NH4)2SO3.

<span class="mw-page-title-main">Ammonium thiosulfate</span> Chemical compound

Ammonium thiosulfate is an inorganic compound with the formula [NH4]2S2O3. It is white crystalline solid with ammonia odor, readily soluble in water, slightly soluble in acetone and insoluble in ethanol and diethyl ether.

<span class="mw-page-title-main">Sulfoxylic acid</span> Chemical compound

Sulfoxylic acid (H2SO2) (also known as hyposulfurous acid or sulfur dihydroxide) is an unstable oxoacid of sulfur in an intermediate oxidation state between hydrogen sulfide and dithionous acid. It consists of two hydroxy groups attached to a sulfur atom. Sulfoxylic acid contains sulfur in an oxidation state of +2. Sulfur monoxide (SO) can be considered as a theoretical anhydride for sulfoxylic acid, but it is not actually known to react with water.

<span class="mw-page-title-main">Polythionates</span>

Polythionates are oxyanions with the formula O3S−Sn−SO−3 (n ≥ 0). They occur naturally and are the products of redox reactions of thiosulfate. Polythionates are readily isolable, unlike the parent polythionic acids.

A sulfite sulfate is a chemical compound that contains both sulfite and sulfate anions [SO3]2− [SO4]2−. These compounds were discovered in the 1980s as calcium and rare earth element salts. Minerals in this class were later discovered. Minerals may have sulfite as an essential component, or have it substituted for another anion as in alloriite. The related ions [O3SOSO2]2− and [(O2SO)2SO2]2− may be produced in a reaction between sulfur dioxide and sulfate and exist in the solid form as tetramethyl ammonium salts. They have a significant partial pressure of sulfur dioxide.

References

  1. 1 2 Atherton Seidell (1919). Solubilities of inorganic and organic compounds c. 2. D. Van Nostrand Company. p. 568.
  2. 1 2 3 Sulewski, Gavin; Thompson, Michael; Mikkelsen, Robert; Norton, Robert; Scott, T., eds. (2020). Improving Potassium Recommendations for Agricultural Crops (Ebook). Springer International Publishing. p. 60. ISBN   978-3-030-59197-7 . Retrieved 6 October 2021.
  3. 1 2 Barbera, J. J.; Metzger, A.; Wolf, M. "Sulfites, Thiosulfates, and Dithionites". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_477.
  4. 1 2 Western Plant Health Association (2018). Barlow, Dave; Pier, Jerome (eds.). Western Fertilizer Handbook (Ebook) (Third Horticulture ed.). Waveland Press. p. 186. ISBN   978-1-4786-3884-1 . Retrieved 6 October 2021.
  5. Zejiang Cai; Suduan Gao; Minggang Xu; Bradley D Hanson (2017). "Evaluation of potassium thiosulfate as a nitrification inhibitor to reduce nitrous oxide emissions". Science of the Total Environment. 618: 243–249. doi: 10.1016/j.scitotenv.2017.10.274 . PMID   29128773.
  6. Ruijun Qin; Suduan Gao; Jason A McDonald; Husein Ajwa; Shachar Shem-Tov; David A Sullivan (2008). "Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields". Chemosphere. 72 (4): 558–563. Bibcode:2008Chmsp..72..558Q. doi:10.1016/j.chemosphere.2008.03.023. PMID   18440581.